Next Article in Journal
Low-Temperature Selective Catalytic Reduction of NO with NH3 over Natural Iron Ore Catalyst
Next Article in Special Issue
One-Pot Synthesis of 7, 7-Dimethyl-4-Phenyl-2-Thioxo-2,3,4,6,7, 8-Hexahydro-1H-Quinazoline-5-OnesUsing Zinc Ferrite Nanocatalyst and Its Bio Evaluation
Previous Article in Journal
Nitrogen and Cobalt Co-Coped Carbon Materials Derived from Biomass Chitin as High-Performance Electrocatalyst for Aluminum-Air Batteries
Previous Article in Special Issue
Enhanced Selective Production of Arenes and Regenerating Rate in Aryl Ether Hydrogenolysis over Mesoporous Nickel in Plug-Flow Reactors
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Catalysts
Volume 9
Issue 11
10.3390/catal9110955
catalysts-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Gold(I) Complexes with Ferrocenylphosphino Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of Carboxylic Acids to Internal Alkynes in Water

by
Javier Francos
1,
María Esther Moreno-Narváez
1,
Victorio Cadierno
1,*,
Diego Sierra
2,*,
Katherine Ariz
2 and
Johana Gómez
3
1
Laboratorio de Compuestos Organometálicos y Catálisis (Unidad Asociada al CSIC), Centro de Innovación en Química Avanzada (ORFEO-CINQA), Departamento de Química Orgánica e Inorgánica, IUQOEM, Facultad de Química, Universidad de Oviedo, Julián Clavería 8, E-33006 Oviedo, Spain
2
Laboratorio de Química Organometálica y Catálisis, Instituto de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Av. Gran Bretaña 1111, Valparaíso 2340000, Chile
3
Núcleo Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Av. Universidad 330, Valparaíso 2340000, Chile
*
Authors to whom correspondence should be addressed.
Catalysts 2019, 9(11), 955; https://doi.org/10.3390/catal9110955
Submission received: 28 October 2019 / Revised: 7 November 2019 / Accepted: 11 November 2019 / Published: 14 November 2019
(This article belongs to the Special Issue Advances in Green Catalysis for Sustainable Organic Synthesis)
Browse Figures
Versions Notes

Abstract

The synthesis and characterization of novel gold(I) complexes containing hydrophilic ferrocenylphosphino sulfonate ligands, i.e., compounds [AuCl{(η5-C5H3PR2(SO3iPr))Fe(η5-C5H5)}] (R = Ph (2a), p-Tol (2b), Cy (2c)), are presented, including a single-crystal X-ray diffraction study on 2a. Complexes 2a–c were checked as catalysts for the intermolecular addition of carboxylic acids to nonactivated internal alkynes using water as a green reaction medium. The best results in terms of activity were obtained with 2a in combination with AgOAc, which was able to promote the selective anti addition of a variety of aromatic, aliphatic, and α,β-unsaturated carboxylic acids to both symmetrical and unsymmetrical internal alkynes at 60 °C, employing metal loadings of only 2 mol %.

1. Introduction

Enol esters represent an important class of synthons in organic chemistry, commonly employed as intermediates, among others, in cross-coupling [1,2,3], asymmetric hydrogenation [4,5,6], and cyclization reactions [7,8,9], as well as monomers in polymerization and oligomerization processes [10,11,12]. Among the different methods of synthesis of these valuable molecules, the intermolecular addition of carboxylic acids to alkynes catalyzed by transition metals (hydro-oxycarbonylation reaction) is probably the most straightforward and atom-economical one because the starting materials are widely available and no byproducts are generated in the process. A large number of catalytic systems, mainly involving Groups 8–11 metals, have been reported in the literature, with those based on ruthenium being probably the most popular [13,14,15,16,17]. However, the vast majority of studies have focused on the hydro-oxycarbonylation of terminal alkynes. Examples of the intermolecular addition of carboxylic acids to internal alkynes still remain scarce [18], and in most of the cases, only activated substrates, such as trifluoromethylated alkynes [19], acetylenic esters [20], ynol ethers [21], ynamides [22], or iodoalkynes [23], have been considered. For nonactivated internal alkynes, only a very limited number of gold- and cobalt-based catalysts have proven effective under mild conditions (temperatures below 100 °C) [24,25,26,27]. It is also worth noting that, despite the growing interest in developing catalytic transformations in environmentally friendly aqueous media [28], efforts devoted to finding catalytic systems able to promote the hydro-oxycarbonylation of alkynes in water have been very scarce, with most of the examples dealing with intramolecular processes [29]. In fact, the only protocol for the intermolecular addition of carboxylic acids to internal alkynes in water that can be currently found in the literature was developed by our group, making use of the gold(I) complex [AuCl(PPh3)] in combination with the chloride abstractor AgOAc [30]. As shown in Scheme 1, the trisubstituted enol ester products were generated with complete Z-stereoselectivity as the result of the anti-addition of the carboxylate anion to the corresponding cationic π-alkyne-Au(I) intermediate.
Given the tremendous effect that ligands can exert in homogeneous Au catalysis [31], we reasoned that a change in the nature of the coordinated phosphine ligand could improve these previous results. In particular, we turned our attention to the ferrocenylphosphino sulfonates 1a–c recently synthesized by us (Scheme 2), because preliminary studies showed their utility as auxiliary P-donor ligands in ruthenium-catalyzed C–H activation processes in aqueous media [32]. In addition, compounds 1a–c represent rare examples of hydrophilic ferrocenylphosphines, a particular class of ligands whose potential in aqueous catalysis remains almost unexplored. Thus, in this work, the preparation of gold(I) complexes containing the ferrocenylphosphines 1a–c is presented, as well as an evaluation of their catalytic activity in hydro-oxycarbonylation reactions of nonactivated internal alkynes in water.

2. Results and Discussion

The treatment of dichloromethane solutions of the ferrocenylphosphino sulfonates 1a–c with one equivalent of [AuCl(SMe2)] at room temperature led to the clean and fast formation of the novel gold(I) complexes 2a–c through the expected displacement of the labile dimethylsufide ligand (Scheme 3).
The characterization of complexes 2a–c, which were isolated as air-stable yellow solids in 79–94% yield, was straightforward following their analytical and spectroscopic data (details are given in Materials and Methods). In particular, the 31P{1H} NMR spectra were very informative, showing in all the cases a singlet resonance at δP 26.2–49.8 ppm, strongly deshielded with respect to that of the free ferrocenylphosphino sulfonates 1a–c (δP from −22.2 to −12.0 ppm) [32]. The 1H and 13C{1H} NMR spectra were also fully consistent with the proposed formulations, featuring two sets of signals for the R substituents of the phosphino groups, as well as for the diastereotopic methyl units of the O–iPr moieties (i.e., two doublet signals at δH 0.91–1.46 ppm (3JHH = 6.0–6.3 Hz) and two singlets at δC 22.6–23.6 ppm), as a consequence of the planar chirality of the ferrocenyl fragments due to the 1,2-disubstitution of one of their Cp rings. In addition, the structure of complex 2a was unambiguously confirmed by means of a single-crystal X-ray diffraction study. X-ray quality crystals were obtained by slow diffusion of hexane into a saturated solution of 2a in dichloromethane. An ORTEP-type view of the molecule, along with selected structural parameters, is shown in Figure 1.
The coordination around the gold atom is almost linear with a P(1)–Au(1)–Cl(1) angle of 175.72(3)°, and bond distances Au(1)–P(1) and Au(1)–Cl(1) of 2.2340(9) and 2.2893(9) Å, respectively. These bonding parameters compare well with those previously found in the solid-state crystal structures of related ferrocenylphosphine–gold(I) complexes, like [Au2Cl2(µ-dppf)] (dppf = 1,1´-bis(diphenylphosphino)ferrocene; Au–P = 2.2262(13) Å, Au–Cl = 2.2815(13) Å, and P–Au–Cl = 179.59(5)°) [33], [Au2Cl2{µ-(η5-1,3-C5H3PPh2(OSiiPr3))2Fe}] (Au–P = 2.2282(9) Å, Au–Cl = 2.2814(10) Å, and P–Au–Cl = 177.35(4)°) [34] or [AuCl{(η5-1,2-C5H3PPh2(1-naphthyl))Fe(η5-C5H5)}] (Au–P = 2.2278(11) Å, Au–Cl = 2.2845(11) Å, and P–Au–Cl = 174.16(5)°) [35]. On the other hand, the observed bond distances within the ferrocenylphosphine sulfonate skeleton were very similar to those found in the structure of the free ligand 1a (± 0.04 Å) [32]. The same can be said about the bond angles, where the most noticeable differences were the increase in ca. 5–6° of the C(1)–P(1)–C(11) and C(1)–P(1)–C(17) angles when passing from 1a to 2a. All these observations indicate a negligible influence of the gold coordination on the geometry of the ligand.
With the complexes [AuCl{(η5-C5H3PR2(SO3iPr))Fe(η5-C5H5)}] (2a–c) in hand, we next explored their catalytic potential in hydro-oxycarbonylation reactions of internal alkynes in water. In particular, a first set of experiments was performed with complex 2a and the model substrates hex-3-yne (3a) and benzoic acid (4a) (see Table 1).
As shown in entry 1, when a mixture of 3a (1.2 mmol), 4a (1 mmol), and complex 2a (0.02 mmol; 2 mol %) in water (3 mL) was heated at 60 °C for 4 h, no reaction was observed, suggesting the need for a halide extractor to generate the catalytically active cationic gold(I) species. In this regard, different silver(I) salts (2 mol%) were screened (entries 2–7), obtaining positive results in all cases. In particular, the best result was achieved with AgOAc, which led to the desired enol ester 5aa in 91% gas chromatography (GC) yield after 4 h of heating (entry 7). Work-up of the reaction mixture allowed for isolation of pure 5aa in 87% yield (see details in Materials and Methods). Employing the same reaction conditions, the catalytic performance of the bis(p-tolyl)phosphino complex 2b was found to be very similar to that shown by complex 2a (entries 8 vs. 7). The dicyclohexylphosphino complex 2c proved to also be active in the addition process, but its effectiveness was slightly lower in comparison to that of 2a and 2b (entry 9 vs. 7 and 8). Although steric effects cannot be discarded, the lower reactivity of 2c is most probably related to the higher electronic density of the metal center, which reduces the electrophilic character of the corresponding gold cation disfavoring the coordination of the alkyne substrate. Also of note is the fact that, as previously observed employing the catalytic system [AuCl(PPh3)]/AgOAc (see Scheme 1) [30], all the reactions collected in Table 1 proceeded cleanly without any side-reaction associated with the hydration of the C≡C bond or oligomerization processes, and with an exquisite anti selectivity (only the Z isomer of 5aa is formed). A blank experiment with AgOAc alone confirmed that gold is responsible for the catalytic activity observed (entry 10). We would also like to highlight in this point that the effectiveness shown by the 2a/AgOAc system in this reaction compares favorably with that reported for [AuCl(PPh3)]/AgOAc (5 mol % of both reagents were needed to generate 5aa in a comparable yield under identical experimental conditions) [30], which could be explained in terms of the higher solubility in the water of complex 2a (ca. 10 mg/mL at 60 °C). However, the different reactivities observed between complexes 2a, 2b, and 2c do not seem to be related to their water solubilities, since the most soluble one 2c (ca. 13 mg/mL at 60 °C) is the least effective (the solubility of 2b is identical to that of 2a).
The scope of Au(I) complex 2a was subsequently explored by varying firstly the carboxylic acid reagent. Thus, as shown in Scheme 4, different benzoic acids 4b–f could be successfully added to hex-3-yne (3a), regardless of the electronic nature and substitution pattern of the aryl ring. As for 5aa, the resulting enol esters 5ab–af were exclusively obtained as the corresponding Z isomers, as assessed by comparison of their NMR data with literature values [30]. The use of 4-hydroxybenzoic acid (4f) led to an interesting result because, in addition to the expected hydro-oxycarbonylation reaction, the hydroalkoxylation of 3a also occurred, leading to the previously unknown enol ester 5af (to obtain this compound in good yield, a 3a/4f ratio of 2.4:1 was employed). We would like to remark here that, although gold-catalyzed intermolecular hydroalkoxylation reactions of alkynes have been extensively studied [36], no previous examples in water can be found in the literature. As exemplified with compounds 5ag–an, the addition process could also be extended to benzylic, homobenzylic, aliphatic, and α,β-unsaturated carboxylic acids, thus confirming the wide scope of 2a towards the carboxylate partner (Scheme 2). The enol esters 5ab–an were isolated, after extraction of the reaction mixture with diethyl ether and subsequent chromatographic purification, in 61–92% yield (conversions ≥ 85% were in all cases observed by GC), with reaction times ranging from 5 to 24 h.
Additional studies varying the nature of the alkyne were also performed. Thus, as observed for hex-3-yne (3a), the addition of benzoic acid to oct-4-yne (3b) and but-2-yne (3c) also proceeded cleanly under the standard conditions, leading to the corresponding enol esters 5ba and 5ca, which were isolated in 82–92% yield (see Scheme 4). In contrast, a very poor result was obtained when diphenylacetylene (3d) was employed as substrate, the reaction leading to a maximum 20% GC yield of the desired enol ester product 5da after 24 h (Scheme 4). The higher steric constraints of this particular alkyne could be behind this negative result.
To complete the study, the catalytic addition of benzoic acid (4a) to a nonsymmetrically substituted alkyne, i.e., 1-phenyl-1-propyne (3e), was finally explored. As shown in Scheme 5, the reaction proceeded in high yield after 20 h, but with a relatively low regioselectivity. Thus, a nonseparable mixture of the regioisomeric enol esters 5ea and 5ea´ was formed in ca. 2.2:1 ratio.

3. Materials and Methods

All the synthetic procedures described in this article were performed under inert atmosphere (dry argon) using vacuum-line and Schlenk or sealed-tube techniques. Organic solvents were purified by standard methods and distilled under inert atmosphere before use [37]. All reagents employed in this work were obtained from commercial suppliers and used as received, with the exception of the ferrocenylphosphino sulfonate ligands (η5-C5H3PR2(SO3iPr))Fe(η5-C5H5) (1a–c) [32] and the gold(I) complex [AuCl(SMe2)] [38], which were synthesized as previously described in the literature. NMR spectra were recorded at room temperature making use of Bruker DPX-300 or AV400 instruments (Billerica, MA, USA). The residual signal of the deuterated solvent was employed as reference for 13C{1H} and 1H NMR chemical shifts, while 85% H3PO4 was used as an external standard for the 31P{1H} NMR measurements. DEPT experiments were systematically performed for all the compounds synthesized. A PerkinElmer 1720-XFT spectrometer (Waltham, MA, USA) and a Hewlett Packard HP6890 apparatus (Supelco Beta-DexTM 120 column, 30 m length, 250 μm diameter, (Palo Alto, CA, USA) were employed for IR and GC measurements, respectively. Elemental analyses and HRMS data (QTOF Bruker Impact II mass spectrometer) were provided by the Analytical Service of the Instituto de Investigaciones Químicas (IIQ-CSIC) of Seville and the General Services of the University of Oviedo, respectively. Merck silica gel 60 (230–400 mesh) was employed for the chromatographic work-ups.

3.1. General Procedure for the Preparation of Complexes [AuCl{(η5-C5H3PR2(SO3iPr))Fe(η5-C5H5)}] (R = Ph (2a), p-Tol (2b), Cy (2c))

In a Schlenk flask filled with Ar and equipped with a stir bar, the corresponding ferrocenylphosphino sulfonate ligand 1a–c (0.40 mmol) was dissolved in 10 mL of dichloromethane. Then, 0.40 mmol (0.119 g) of [AuCl(SMe2)] was added to the resulting solution, and the mixture was stirred at room temperature for 1 h (a color change from orange-red to yellow was observed). After this time, the solvent was removed under vacuum, and the yellow solid obtained recrystallized from a 1:1 v/v dichloromethane/hexane mixture (ca. 20 mL), washed with hexane (ca. 10 mL), and dried in vacuo. Characterization data for the resulting Au(I) complexes 2a–c are as follows:

3.1.1. [AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)

Yield: 0.235 g (81%). 31P{1H} NMR (121 MHz, CDCl3): δ = 27.7 (s) ppm. 1H NMR (300 MHz, CDCl3): δ = 7.76–7.69 (m, 2H, Ph), 7.58–7.45 (m, 8H, Ph), 5.17 and 3.87 (s, 1H each, CH of C5H3), 4.73 (sept, 1H, 3JHH = 6.3 Hz, CHMe2), 4.63 (s, 6H, C5H5 and CH of C5H3), 1.14 and 0.91 (d, 3H each, 3JHH = 6.3 Hz, CHMe2) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 134.6 and 133. 9 (d, JPC = 14.7 Hz, CHortho or CHmeta of Ph), 132.1 and 131.8 (d, JPC = 2.2 Hz, CHpara of Ph), 129.7 (d, JPC = 61.1 Hz, Cipso of Ph), 129.5 (d, JPC = 62.0 Hz, Cipso of Ph), 129.0 (d, JPC = 12.0 Hz, CHortho or CHmeta of Ph), 128.8 (d, JPC = 12.2 Hz, CHortho or CHmeta of Ph), 88.9 (d, JPC = 12.0 Hz, C of C5H3), 77.3 (d, JPC = 5.7 Hz, CH of C5H3), 76.5 (s, CHMe2), 75.9 (d, JPC = 4.6 Hz, CH of C5H3), 73.5 (s, C5H5), 72.0 (d, JPC = 6.9 Hz, CH of C5H3), 71.2 (d, JPC = 66.2 Hz, C of C5H3), 23.0 and 22.7 (s, CHMe2) ppm. IR (KBr): ν = 3107 (w), 2981 (w), 2933 (w), 1436 (m), 1330 (s), 1207 (m), 1166 (s), 1151 (m), 1096 (m), 1037 (w), 961 (w), 901 (m), 868 (s), 838 (m), 750 (m), 693 (m), 659 (s), 599 (m), 481 (m) cm−1. Elemental analysis calcd. (%) for C25H25O3AuClFePS: C 41.43, H 3.48; found: C 41.47, H 3.47.

3.1.2. [AuCl{(η5-C5H3P(p-Tol)2(SO3iPr))Fe(η5-C5H5)}] (2b)

Yield: 0.238 g (79%). 31P{1H} NMR (121 MHz, CDCl3): δ = 26.2 (s) ppm. 1H NMR (300 MHz, CDCl3): δ = 7.64–7.57 (m, 2H, C6H4Me), 7.45–7.38 (m, 2H, C6H4Me), 7.31–7.22 (m, 4H, C6H4Me), 5.15 and 3.88 (s, 1H each, CH of C5H3), 4.71 (sept, 1H, 3JHH = 6.0 Hz, CHMe2), 4.62 (s, 6H, C5H5 and CH of C5H3), 2.44 and 2.40 (s, 3H each, C6H4Me), 1.15 and 0.93 (d, 3H each, 3JHH = 6.0 Hz, CHMe2) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 142.6 and 142.3 (s, Cpara of C6H4Me), 134.5 and 133. 9 (d, JPC = 15.1 Hz, CHortho or CHmeta of C6H4Me), 129.7 and 129.5 (d, JPC = 12.3 Hz, CHortho or CHmeta of C6H4Me), 126.5 and 126.3 (d, JPC = 63.8 Hz, Cipso of C6H4Me), 88.7 (d, JPC = 1.9 Hz, C of C5H3), 77.3 (d, JPC = 6.0 Hz, CH of C5H3), 76.5 (s, CHMe2), 75.8 (d, JPC = 4.5 Hz, CH of C5H3), 73.4 (s, C5H5), 71.7 (d, JPC = 6.9 Hz, CH of C5H3), 72.0 (d, JPC = 65.9 Hz, C of C5H3), 23.0 and 22.6 (s, CHMe2), 21.5 and 21.4 (s, C6H4Me) ppm. IR (KBr): ν = 2978 (w), 2924 (w), 1597 (w), 1497 (w), 1368 (m), 1357 (m), 1331 (m), 1202 (m), 1166 (s), 1100 (s), 1035 (w), 960 (w), 916 (s), 881 (m), 833 (w), 806 (m), 754 (w), 627 (m), 507 (m), 495 (m) cm−1. Elemental analysis calcd. (%) for C27H29O3AuClFePS: C 43.08, H 3.88; found: C 43.15, H 3.84.

3.1.3. [AuCl{(η5-C5H3PCy2(SO3iPr))Fe(η5-C5H5)}] (2c)

Yield: 0.277 g (94%). 31P{1H} NMR (121 MHz, CDCl3): δ = 49.8 (s) ppm. 1H NMR (300 MHz, CDCl3): δ = 5.09, 4.90 and 4.76 (s, 1H each, CH of C5H3), 5.02 (sept, 1H, 3JHH = 6.0 Hz, CHMe2), 4.57 (s, 5H, C5H5), 2.91–2.78 and 2.61–2.55 (m, 1H each, CH of Cy), 2.07,1.65 (m, 12H, CH2 of Cy), 1.48–1.12 (m, 8H, CH2 of Cy), 1.46 and 1.32 (d, 3H each, 3JHH = 6.0 Hz, CHMe2) ppm. 13C{1H} NMR (100 MHz, CDCl3): δ = 87.0 (d, JPC = 3.1 Hz, C of C5H3), 81.5 (d, JPC = 17.6 Hz, CH of C5H3), 77.2 (s, CHMe2), 75.3 (d, JPC = 3.0 Hz, CH of C5H3), 73.2 (s, C5H5), 72.1 (d, JPC = 9.5 Hz, CH of C5H3), 69.4 (d, JPC = 49.8 Hz, C of C5H3), 35.7 (d, JPC = 33.2 Hz, CH of Cy), 35.2 (d, JPC = 33.9 Hz, CH of Cy), 33.5 (d, JPC = 3.9 Hz, CH2 of Cy), 31.4 (d, JPC = 2.6 Hz, CH2 of Cy), 29.2, 28.6, 25.7 and 25.6 (s, CH2 of Cy), 26.7 (d, JPC = 13.6 Hz, CH2 of Cy), 26.6 (d, 2C, JPC = 6.9 Hz, CH2 of Cy), 26.5 (d, JPC = 13.2 Hz, CH2 of Cy), 23.6 and 22.9 (s, CHMe2) ppm. IR (KBr): ν = 2928 (s), 2852 (m), 1449 (w), 1369 (s), 1334 (m), 1204 (m), 1167 (s), 1093 (w), 1047 (w), 1003 (w), 905 (s), 876 (s), 837 (m), 756 (m), 628 (s), 508 (m), 483 (w) cm−1. Elemental analysis calcd. (%) for C25H37O3AuClFePS: C 40.75, H 5.06; found: C 40.80, H 5.10.

3.2. General Procedure for the Addition of Carboxylic Acids to Internal Alkynes Catalyzed by Complex 2a

Under an argon atmosphere, the corresponding internal alkyne 3a–e (1.2 mmol) and carboxylic acid 4a–n (1 mmol), the gold complex [AuCl{(η5–C5H3PPh2(SO3iPr))Fe(η5–C5H5)}] (2a) (0.014 g; 0.02 mmol), AgOAc (0.003 g; 0.02 mmol), and water (3.0 mL) were introduced into a Teflon-capped sealed tube, and the reaction mixture was stirred at 60 °C for the indicated time (see Scheme 4 and Scheme 5). The course of the reaction was monitored regularly, taking samples of ca. 5 μL, which, after extraction with CH2Cl2, were analyzed by GC. Once the reaction finished, the mixture was extracted with diethyl ether (3 x 5 mL), and the organic phase was dried over MgSO4 and evaporated to dryness. The resulting oily residue was purified by flash column chromatography over silica gel using diethyl ether/hexane (1:10) as eluent. The identity of the enol ester products was assessed by comparison of their NMR spectroscopic data with those previously reported by us [30] or, in the case of 5ag, by Tsukada and coworkers [39]. Copies of the NMR spectra are included in the Supplementary Materials.

3.3. Synthesis and Characterization of (Z)-Hex-3-en-3-yl 4-(((Z)-Hex-3-en-3-yl)oxy)benzoate 5af

The novel enol ester 5af, isolated as a colourless oil after 24 h of heating, was obtained following the general procedure detailed in Section 3.2, starting from hex-3-yne (3a; 0.273 mL; 2.4 mmol) and 4-hydroxybenzoic acid (4f; 0.138 g; 1 mmol). Yield: 0.184 g (61%). 1H NMR (300 MHz, CDCl3): δ = 8.09–8.06 (m, 2H, CHarom), 7.00–6.98 (m, 2H, CHarom), 5.11 (m, 2H, =CH), 2.33–2.28 (m, 2H, CH2), 2.20–2.16 (m, 2H, CH2), 2.02–1.96 (m, 4H, CH2), 1.12–1.08 (m, 6H, CH3), 1.06–0.93 (m, 6H, CH3) ppm. 13C{1H} NMR (75 MHz, CDCl3): δ = 164.2 (s, C=O), 161.2 and 122.7 (s, Carom), 151.1 and 149.5 (s, =C), 132.1 and 115.2 (s, CHarom), 117.5 and 117.0 (s, =CH), 26.6, 25.6, 18.8, and 18.6 (s, CH2), 13.9, 13.8, 11.4, and 11.3 (s, CH3) ppm. IR (neat): ν = 2968 (m), 2912 (m), 2875 (m), 1729 (s), 1691 (m), 1604 (s), 1504 (s), 1462 (m), 1418 (w), 1376 (w), 1263 (s), 1237 (s), 1181 (m), 1086 (s), 1022 (w), 972 (w), 850 (m), 746 (m) cm–1. HRMS (ESI): m/z 325.1763, [M + Na+] (calcd. for C19H26O3Na: 325.1774).

3.4. X-ray Crystal Structure Determination of Compound 2a

Crystals suitable for X-ray diffraction analysis were obtained by slow diffusion of hexane into a saturated solution of compound 2a in dichloromethane. The most relevant crystal and refinement data are collected in Table 2. Diffraction data were recorded on an Oxford Diffraction Xcalibur Nova single-crystal diffractometer, using Cu-Kα radiation (λ = 1.5418 Å), with a crystal-to-detector distance fixed at 62 mm and using the oscillation method, with 1° oscillation and variable exposure time per frame of 2.5–6.5 s. The data collection strategy was calculated with the program CrysAlis Pro CCD [40]. Data reduction and cell refinement were performed with the program CrysAlis Pro RED [40]. Empirical absorption correction was applied by means of a SCALE3 ABSPACK algorithm as implemented in the program CrysAlis Pro RED [40]. The software package WINGX was used for space group determination, structure solution, and refinement [41]. The structure was solved by direct methods using SHELXL97 [42]. Isotropic least-squares refinement on F2 using SHELXL97 was performed [42]. During the final stages of the refinement, all the positional parameters and the anisotropic temperature factors of all the non-H atoms were refined. The coordinates of the H atoms were found from different Fourier maps and included in the refinement with isotropic parameters. The function minimized was [Σw(Fo2 − Fc2)/Σw(Fo2)]½ where w = 1/[σ2(Fo2) + (0.0457P)2 + 0.2366P] with σ(Fo2) from counting statistics and P = (Max (Fo2,0) + 2Fc2)/3. Atomic scattering factors were taken from the International Tables for X-ray Crystallography [43]. Geometrical calculations were made with PARST [44]. The crystallographic plots were made with DIAMOND [45]. Supplementary crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Centre, CCDC-1961685.

4. Conclusions

In summary, new gold(I) complexes featuring hydrophilic ferrocenylphophino sulfonate ligands were synthesized, i.e., compounds [AuCl{(η5-C5H3PR2(SO3iPr))Fe(η5-C5H5)}] (R = Ph (2a), p-Tol (2b), Cy (2c)), and evaluated as potential catalysts for hydro-oxycarbonylation reactions of nonactivated internal alkynes in water. In combination with AgOAc, all of them became active, delivering the corresponding enol ester products with complete Z-selectivity. Employing 2a/AgOAc, whose activity was found to be superior to that of the previously reported [AuCl(PPh3)]/AgOAc system, the scope of the process could also be demonstrated. The work presented herein provides additional evidence of the utility of ferrocenylphophino sulfonates (η5-C5H3PR2(SO3iPr))Fe(η5-C5H5) (1a-c) as auxiliary ligands for metal-catalyzed organic reactions in environmentally friendly aqueous media.

Supplementary Materials

The following are available online at https://www.mdpi.com/2073-4344/9/11/955/s1, Figures S1–S9: NMR spectra of the gold(I) complexes 2a–c, and Figures S10–S44: NMR spectra of the enol esters 5aa–ea.

Author Contributions

Conceptualization, V.C. and D.S.; Synthesis of ligands, K.A. and J.G.; Synthesis of complexes and catalytic experiments, J.F. and M.E.M.-N.; X-ray diffraction, J.F.; All the authors contributed to the discussion of the experimental results as well as writing and editing of the manuscript.

Funding

This research was funded by the Spanish Ministry of Economy, Industry, and Competitiveness (MINECO project CTQ2016-75986-P) and the University of Oviedo (project PAPI-18-GR-2011-0032).

Acknowledgments

M.E.M.-N. thanks the National Autonomous University of México (UNAM) and CONACyT (scholarship 620618) for a mobility grant to make a short stay at the University of Oviedo. K.A. thanks the CONICYT-PFCHA (scholarship 2018-21181046) and PIIC program of the USM.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Gooβen, L.J.; Paetzold, J. Decarbonylative Heck olefination of enol esters: Salt-free and environmentally friendly access to vinyl arenes. Angew. Chem. Int. Ed. 2004, 43, 1095–1098. [Google Scholar]
  2. Geibel, I.; Dierks, A.; Schmidtmann, M.; Christoffers, J. Formation of δ-lactones by cerium catalyzed, Baeyer-Villiger-type coupling of β-oxoesters, enol acetates, and dioxygen. J. Org. Chem. 2016, 81, 7790–7798. [Google Scholar] [CrossRef] [PubMed]
  3. Geibel, I.; Christoffers, J. Synthesis of 1,4-diketones from β-oxo esters and enol acetates by cerium-catalyzed oxidative umpolung reaction. Eur. J. Org. Chem. 2016, 2016, 918–920. [Google Scholar] [CrossRef]
  4. Kleman, P.; González-Liste, P.J.; García-Garrido, S.E.; Cadierno, V.; Pizzano, A. Highly enentioselective hydrogenation of 1-alkylvinyl benzoates: A simple, nonenzymatic access to chiral 2-alkanols. Chem. A Eur. J. 2013, 19, 16209–16212. [Google Scholar] [CrossRef] [PubMed]
  5. León, F.; González-Liste, P.J.; García-Garrido, S.E.; Arribas, I.; Rubio, M.; Cadierno, V.; Pizzano, A. Broad scope synthesis of ester precursors of nonfunctionalized chiral alcohols based on the asymmetric hydrogenation of α,β-dialky, α,β-diaryl, and α-alkyl-β-aryl-vinyl esters. J. Org. Chem. 2017, 82, 5852–5867. [Google Scholar] [CrossRef]
  6. Jia, J.; Fan, D.; Zhang, J.; Zhang, Z.; Zhang, W. An atropos biphenyl bisphosphine ligand with 2,2′-tert-butylmethylphosphino groups for the rhodium-catalyzed asymmetric hydrogenation of enol esters. Adv. Synth. Catal. 2018, 360, 3793–3800. [Google Scholar] [CrossRef]
  7. Corey, E.J.; Ghosh, A.K. Manganese (III)-promoted annulation of enol ethers and esters to fused spiro 2-cyclopentenones. Tetrahedron Lett. 1987, 28, 175–178. [Google Scholar] [CrossRef]
  8. Panda, N.; Mothkuri, R.; Pal, A.; Paital, A.R. Copper-catalyzed synthesis of α-naphthols from enol esters. Adv. Synth. Catal. 2013, 355, 2809–2814. [Google Scholar] [CrossRef]
  9. Panda, N.; Mishra, P.; Mattan, I. Synthesis of isocoumarins via silver (I)-mediated annulation of enol esters. J. Org. Chem. 2016, 81, 1047–1056. [Google Scholar] [CrossRef]
  10. Jena, R.K.; Das, U.K.; Ghorai, A.; Bhattacharjee, M. Ruthenium-catalyzed addition of carboxylic acids to propargylic alcohols: An easy route to O-dienyl esters and their tandem atom-transfer radical polymerization. Eur. J. Org. Chem. 2016, 36, 6015–6021. [Google Scholar] [CrossRef]
  11. Foarta, F.; Landis, C.R. Condensation oligomers with sequence control but without coupling reagents and protecting groups via asymmetric hydroformylation and hydroacyloxylation. J. Org. Chem. 2016, 81, 11250–11255. [Google Scholar] [CrossRef] [PubMed]
  12. Hwang, J.; Lee, H.-C.; Antonietti, M.; Schmidt, B.V.K.J. Free radical and RAFT polymerization of vinyl esters in metal-organic frameworks. Polym. Chem. 2017, 8, 6204–6208. [Google Scholar] [CrossRef]
  13. Alonso, F.; Beletskaya, I.; Yus, M. Transition-metal-catalyzed addition of heteroatom-hydrogen bonds to alkynes. Chem. Rev. 2004, 104, 3079–3160. [Google Scholar] [CrossRef] [PubMed]
  14. Beller, M.; Seayad, J.; Tillack, A.; Jiao, H. Catalytic Markovnikov and anti-Markovnikov functionalization of alkenes and alkynes: Recent developments and trends. Angew. Chem. Int. Ed. 2004, 43, 3368–3398. [Google Scholar] [CrossRef]
  15. Hintermann, L. Recent developments in metal-catalyzed additions of oxygen nucleophiles to alkenes and alkynes. Top. Organomet. Chem. 2010, 31, 123–155. [Google Scholar]
  16. Patil, N.T.; Kavthe, R.D.; Shinde, V.S. Transition metal-catalyzed addition of C-, N- and O-nucleophiles to unactivated C-C multiple bonds. Tetrahedron 2012, 68, 8079–8146. [Google Scholar] [CrossRef]
  17. Bruneau, C. Group 8 metals-catalyzed O-H bond addition to unsaturated molecules. Top. Organomet. Chem. 2013, 43, 203–230. [Google Scholar]
  18. González-Liste, P.J.; Francos, J.; García-Garrido, S.E.; Cadierno, V. The intermolecular hydro-oxycarbonylation of internal alkynes: Current state of the art. Arkivoc 2018, ii, 17–39. [Google Scholar] [CrossRef]
  19. Kawatsura, M.; Namioka, J.; Kajita, K.; Yamamoto, M.; Tsuji, H.; Itoh, T. Ruthenium-catalyzed regio- and stereoselective addition of carboxylic acids to aryl and trifluoromethyl group substituted unsymmetrical internal alkynes. Org. Lett. 2011, 13, 3285–3287. [Google Scholar] [CrossRef]
  20. Lu, X.; Zhu, G.; Ma, S. A novel regio- and stereo-specific hydroacetoxylation reaction of 2-alkynoic acid derivatives. Tetrahedron Lett. 1992, 33, 7205–7206. [Google Scholar] [CrossRef]
  21. Yin, J.; Bai, Y.; Mao, M.; Zhu, G. Silver-catalyzed regio- and stereoselective addition of carboxylic acids to ynol ethers. J. Org. Chem. 2014, 79, 9179–9185. [Google Scholar] [CrossRef] [PubMed]
  22. Smith, D.L.; Goundry, W.R.F.; Lam, H.W. Palladium-catalyzed hydroacyloxylation of ynamides. Chem. Commun. 2012, 48, 1505–1507. [Google Scholar] [CrossRef] [PubMed]
  23. González-Liste, P.J.; Francos, J.; García-Garrido, S.E.; Cadierno, V. Gold-catalyzed regio- and stereoselective addition of carboxylic acids to iodoalkynes: Access to (Z)-β-iodoenol esters and 1,4-disubstituted (Z)-enynyl esters. J. Org. Chem. 2017, 82, 1507–1516. [Google Scholar] [CrossRef] [PubMed]
  24. Chary, B.C.; Kim, S. Gold (I)-catalyzed addition of carboxylic acids to alkynes. J. Org. Chem. 2010, 75, 7928–7931. [Google Scholar] [CrossRef] [PubMed]
  25. Wang, Y.; Wang, Z.; Li, Y.; Wu, G.; Cao, Z.; Zhang, L. A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes. Nat. Commun. 2014, 5, 3470. [Google Scholar] [CrossRef]
  26. Dupuy, S.; Gasperini, D.; Nolan, S.P. Highly efficient gold (I)-catalyzed regio- and stereoselective hydrocarboxylation of internal alkynes. ACS Catal. 2015, 5, 6918–6921. [Google Scholar] [CrossRef]
  27. Chen, J.-F.; Li, C. Enol ester synthesis via cobalt-catalyzed regio- and stereoselective addition of carboxylic acids to alkynes. Org. Lett. 2018, 20, 6719–6724. [Google Scholar] [CrossRef]
  28. Dixneuf, P.H.; Cadierno, V. (Eds.) Metal-Catalyzed Reactions in Water; Wiley-VCH: Weinheim, Germany, 2013. [Google Scholar]
  29. Francos, J.; Cadierno, V. Metal-catalyzed intra- and intermolecular addition of carboxylic acids to alkynes in aqueous media: A review. Catalysts 2017, 7, 328. [Google Scholar] [CrossRef]
  30. González-Liste, P.J.; García-Garrido, S.E.; Cadierno, V. Gold (I)-catalyzed addition of carboxylic acids to internal alkynes in aqueous medium. Org. Biomol. Chem. 2017, 15, 1670–1679. [Google Scholar] [CrossRef]
  31. Gorin, D.J.; Sherry, B.D.; Toste, F.D. Ligands effects in homogeneous Au catalysis. Chem. Rev. 2008, 108, 3351–3378. [Google Scholar] [CrossRef]
  32. Sierra, D.; Contreras, C.; Francos, J.; Gómez, J.; Cadierno, V. Novel ferrocenylphosphino sulfonates: Synthesis, crystal structure and preliminary application as ligands in aqueous catalysis. J. Organomet. Chem. 2018, 854, 106–112. [Google Scholar] [CrossRef]
  33. Canales, F.; Gimeno, M.C.; Jones, P.G.; Laguna, A.; Sarroca, C. Substitution reaction studies on [Au2Cl2(µ-dppf)] (dppf = 1,1′-bis(diphenylphosphino)ferrocene). Synthesis of the first gold (I) complex with a µ3-2-pyridinethiolate ligand. Inorg. Chem. 1997, 36, 5206–5211. [Google Scholar] [CrossRef]
  34. Rampazzi, V.; Roger, J.; Amardeil, R.; Penouilh, M.-J.; Richard, P.; Fleurat-Lessard, P.; Hierson, J.-C. Gold (I) complexes of ferrocenyl polyphosphines: Aurophilic gold chloride formation and phosphine-concerted shuttling of a dinuclear [ClAu···AuCl] fragment. Inorg. Chem. 2016, 55, 10907–10921. [Google Scholar] [CrossRef] [PubMed]
  35. Delpont, N.; Escofet, I.; Pérez-Galán, P.; Spiegl, D.; Raducan, M.; Bour, C.; Sinisi, R.; Echavarren, A. Modular chiral gold (I) phosphite complexes. Catal. Sci. Technol. 2013, 3, 3007–3012. [Google Scholar] [CrossRef]
  36. Goodwin, J.A.; Aponick, A. Regioselectivity in the Au-catalyzed hydration and hydroalkoxylation of alkynes. Chem. Commun. 2015, 51, 8730–8741. [Google Scholar] [CrossRef]
  37. Armarego, W.L.F.; Chai, C.L.L. Purification of Laboratory Chemicals, 5th ed.; Butterworth-Heinemann: Oxford, UK, 2003. [Google Scholar]
  38. Brandys, M.-C.; Jennings, M.C.; Puddephatt, R.J. Luminescent gold (I) macrocycles with diphosphine and 4, 4´-bipyridyl ligands. J. Chem. Soc. Dalton Trans. 2000, 4601–4606. [Google Scholar] [CrossRef]
  39. Tsukada, N.; Takahashi, A.; Inoue, Y. Hydrocarboxylation of unactivated internal alkynes with carboxylic acids catalyzed by dinuclear palladium complexes. Tetrahedron Lett. 2011, 52, 248–250. [Google Scholar] [CrossRef][Green Version]
  40. CrysAlisPro CCD & CrysAlisPro RED; Oxford Diffraction Ltd.: Oxford, UK, 2008.
  41. Farrugia, L.J. WinGX and ORTEP for Windows: An update. J. Appl. Cryst. 2012, 45, 849–854. [Google Scholar] [CrossRef]
  42. Sheldrick, G.M. SHELXL97: Program for the Refinement of Crystal Structures; University of Göttingen: Göttingen, Germany, 1997. [Google Scholar]
  43. Wilson, A.J.C. (Ed.) International Tables for X-ray Crystallography, Volume, C; Kluwer Academic Publishers: Dordrecht, The Netherlands, 1992. [Google Scholar]
  44. Nardelli, M. PARST: A system of FORTRAN routines for calculating molecular structure parameters from results of crystal structure analyses. Comput. Chem. 1983, 7, 95–98. [Google Scholar] [CrossRef]
  45. Brandenburg, K.; Putz, H. DIAMOND; Crystal Impact GbR: Bonn, Germany, 1999; Available online: http://www.crystalimpact.com/diamond (accessed on 1 September 2019).
Catalysts 09 00955 sch001
Scheme 1. Catalytic addition of carboxylic acids to internal alkynes in H2O, employing [AuCl(PPh3)].
Scheme 1. Catalytic addition of carboxylic acids to internal alkynes in H2O, employing [AuCl(PPh3)].
Catalysts 09 00955 sch001
Catalysts 09 00955 sch002
Scheme 2. Synthetic route employed for the preparation of the ferrocenyl sulfonate ligands 1a–c.
Scheme 2. Synthetic route employed for the preparation of the ferrocenyl sulfonate ligands 1a–c.
Catalysts 09 00955 sch002
Catalysts 09 00955 sch003
Scheme 3. Synthesis of the ferrocenylphosphino sulfonate–gold(I) complexes 2a–c.
Scheme 3. Synthesis of the ferrocenylphosphino sulfonate–gold(I) complexes 2a–c.
Catalysts 09 00955 sch003
Catalysts 09 00955 g001
Figure 1. ORTEP-type view of the structure of complex 2a showing the crystallographic labelling scheme. Hydrogen atoms have been omitted for clarity. Thermal ellipsoids are drawn at the 30% probability level. Selected bond distances (Å) and angles (deg): Fe(1)–C* = 1.6300(5); Fe(1)–C** = 1.6545(5); Au(1)–Cl(1) = 2.2893(9); Au(1)–P(1) = 2.2340(9); P(1)–C(1) = 1.805(4); P(1)–C(11) = 1.823(4); P(1)–C(17) = 1.808(4); S(1)–C(2) = 1.741(4); S(1)–O(1) = 1.570(2); S(1)–O(2) = 1.426(3); S(1)–O(3) = 1.429(3); O(1)–C(23) = 1.486(4); C*–Fe–C** = 175.67(4); P(1)–Au(1)–Cl(1) = 175.72(3); Au(1)–P(1)–C(1) = 115.6(1); Au(1)–P(1)–C(11) = 115.1(1); Au(1)–P(1)–C(11) = 110.2(1); C(1)–P(1)–C(11) = 105.5(2); C(1)–P(1)–C(17) = 102.8(2); C(11)–P(1)–C(17) = 106.5(2); C(2)–S(1)–O(1) = 103.4(2); C(2)–S(1)–O(2) = 108.3(2); C(2)–S(1)–O(3) = 109.3(2); O(1)–S(1)–O(2) = 110.8(2); O(1)–S(1)–O(3) = 104.2(2); O(2)–S(1)–O(3) = 119.8(2); S(1)–O(1)–C(23) = 120.4(2); C* and C** denote the centroids of the cyclopentadienyl rings (C(1), C(2), C(3), C(4), and C(5), and C(6), C(7), C(8), C(9), and C(10), respectively).
Figure 1. ORTEP-type view of the structure of complex 2a showing the crystallographic labelling scheme. Hydrogen atoms have been omitted for clarity. Thermal ellipsoids are drawn at the 30% probability level. Selected bond distances (Å) and angles (deg): Fe(1)–C* = 1.6300(5); Fe(1)–C** = 1.6545(5); Au(1)–Cl(1) = 2.2893(9); Au(1)–P(1) = 2.2340(9); P(1)–C(1) = 1.805(4); P(1)–C(11) = 1.823(4); P(1)–C(17) = 1.808(4); S(1)–C(2) = 1.741(4); S(1)–O(1) = 1.570(2); S(1)–O(2) = 1.426(3); S(1)–O(3) = 1.429(3); O(1)–C(23) = 1.486(4); C*–Fe–C** = 175.67(4); P(1)–Au(1)–Cl(1) = 175.72(3); Au(1)–P(1)–C(1) = 115.6(1); Au(1)–P(1)–C(11) = 115.1(1); Au(1)–P(1)–C(11) = 110.2(1); C(1)–P(1)–C(11) = 105.5(2); C(1)–P(1)–C(17) = 102.8(2); C(11)–P(1)–C(17) = 106.5(2); C(2)–S(1)–O(1) = 103.4(2); C(2)–S(1)–O(2) = 108.3(2); C(2)–S(1)–O(3) = 109.3(2); O(1)–S(1)–O(2) = 110.8(2); O(1)–S(1)–O(3) = 104.2(2); O(2)–S(1)–O(3) = 119.8(2); S(1)–O(1)–C(23) = 120.4(2); C* and C** denote the centroids of the cyclopentadienyl rings (C(1), C(2), C(3), C(4), and C(5), and C(6), C(7), C(8), C(9), and C(10), respectively).
Catalysts 09 00955 g001
Catalysts 09 00955 sch004
Scheme 4. Addition of different carboxylic acids to symmetrically substituted internal alkynes (isolated yields are given).
Scheme 4. Addition of different carboxylic acids to symmetrically substituted internal alkynes (isolated yields are given).
Catalysts 09 00955 sch004
Catalysts 09 00955 sch005
Scheme 5. Addition of benzoic acid to 1-phenyl-1-propyne catalyzed by the gold(I) complex 2a.
Scheme 5. Addition of benzoic acid to 1-phenyl-1-propyne catalyzed by the gold(I) complex 2a.
Catalysts 09 00955 sch005
Table 1. Addition of benzoic acid (4a) to hex-3-yne (3a) catalyzed by complexes 2a–c in water.1.
Table 1. Addition of benzoic acid (4a) to hex-3-yne (3a) catalyzed by complexes 2a–c in water.1.
Catalysts 09 00955 i001
EntryCatalystSilver saltYield (%)2
1[AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)----0
2[AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)AgPF679
3[AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)AgSbF649
4[AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)AgNO387
5[AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)AgOTs86
6[AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)AgOTf82
7[AuCl{(η5-C5H3PPh2(SO3iPr))Fe(η5-C5H5)}] (2a)AgOAc91 (87)3
8[AuCl{(η5-C5H3P(p-Tol)2(SO3iPr))Fe(η5-C5H5)}] (2b)AgOAc89
9[AuCl{(η5-C5H3PCy2(SO3iPr))Fe(η5-C5H5)}] (2c)AgOAc77
10-----------AgOAc4
1 All the reactions were performed under Ar atmosphere at 60 °C using 1.2 mmol of hex-3-yne (3a), 1.0 mmol of benzoic acid (4a), and 3 mL of water. 2 Yields of 5aa determined by gas chromatography (GC). 3 Isolated yield after work-up in brackets.
Table 2. Crystal data and structure refinement details for compound 2a.
Table 2. Crystal data and structure refinement details for compound 2a.
Chemical FormulaC25H25O3AuClFePS
fw724.74
T (K)130(1)
cryst. syst.monoclinic
space groupP 21/n
cryst. size mm30.24 x 0.10 x 0.07
a, Å10.15090(10)
b, Å14.6795(2)
c, Å16.9056(2)
α, deg90
β, deg101.7130(10)
γ, deg90
Z4
V, Å32466.65(5)
ρcalcd, g cm–31.952
μ, mm−118.351
F(000)1408
θ range, deg3.0104 to 69.6789
index ranges−10 ≤ h ≤ 12; −16 ≤ k ≤ 17; −20 ≤ l ≤ 18
completeness to θmax98%
no. of data collected12340
no. of unique data4556
no. of parameters/restrains332/0
refinement methodfull-matrix least-squares on F2
goodness of fit on F21.082
R1a [I > 2σ(I)] 0.0271
wR2a [I > 2σ(I)]0.0723
R1 (all data)0.0292
wR2 (all data)0.0741
a R1 = ∑(|Fo| − |Fc|)/∑|Fo|; wR2 = {∑[w(Fo2 − Fc2)∑]/ ∑[w(Fo2)2]}½.

Share and Cite

MDPI and ACS Style

Francos, J.; Moreno-Narváez, M.E.; Cadierno, V.; Sierra, D.; Ariz, K.; Gómez, J. Gold(I) Complexes with Ferrocenylphosphino Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of Carboxylic Acids to Internal Alkynes in Water. Catalysts 2019, 9, 955. https://doi.org/10.3390/catal9110955

AMA Style

Francos J, Moreno-Narváez ME, Cadierno V, Sierra D, Ariz K, Gómez J. Gold(I) Complexes with Ferrocenylphosphino Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of Carboxylic Acids to Internal Alkynes in Water. Catalysts. 2019; 9(11):955. https://doi.org/10.3390/catal9110955

Chicago/Turabian Style

Francos, Javier, María Esther Moreno-Narváez, Victorio Cadierno, Diego Sierra, Katherine Ariz, and Johana Gómez. 2019. "Gold(I) Complexes with Ferrocenylphosphino Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of Carboxylic Acids to Internal Alkynes in Water" Catalysts 9, no. 11: 955. https://doi.org/10.3390/catal9110955

APA Style

Francos, J., Moreno-Narváez, M. E., Cadierno, V., Sierra, D., Ariz, K., & Gómez, J. (2019). Gold(I) Complexes with Ferrocenylphosphino Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of Carboxylic Acids to Internal Alkynes in Water. Catalysts, 9(11), 955. https://doi.org/10.3390/catal9110955

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop