Synergy between Main Group and Transition Metal Chemistry

A special issue of Inorganics (ISSN 2304-6740).

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 14793

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Guest Editor
School of Engineering and Physical Sciences, Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
Interests: homogeneous catalysis; organometallic chemistry; phosphorus chemistry; C–H activation; rare-earth chemistry
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Guest Editor
Inorganic Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK
Interests: main group chemistry; bond activation and catalysis; small molecule activation; multiple bonds; Lewis acids in detection/sensing

Special Issue Information

Dear Colleagues,

Modern Inorganic Chemistry is split up into many fields, including Solid-State Chemistry, Bioinorganic Chemistry, and Heterogeneous Catalysis to name but a few. Two core areas of Inorganic Chemistry that have been of huge importance over the last 50 years are Transition Metal Chemistry, focusing on the d-block metals, and Main Group Chemistry, which studies the s- and p-block elements. In the 21st century, we see huge potential in discovery groundbreaking results from the combination of different fields of chemistry driven by the different properties and advantages that can be exploited from different areas of the periodic table as well as the different approaches that each sub-field takes. This Special Issue explores the idea of synergy between transition metal and main group systems, which is likely to be of increasing importance as many more new reactions and species are discovered. This includes improved homogeneous catalysts that exploit the active participation of ligands in the catalytic cycle (p-block chemistry combined with traditional reactivity modes of the late transition metals), borylation reactions (driven by transition metal boryl species), and many others.

For this Special Issue, we are seeking to showcase the extent and depth of current research that combines main group and transition metal chemistry. Often, this can utilize organometallic chemistry as the bridge between these fields, but this is not exclusive. Therefore, we invite you to contribute papers that will be openly accessible, allowing your research to inform and influence the scientists working in these areas to help push the boundaries between these exciting areas.

Dr. Stephen Mansell
Prof. Dr. Simon Aldridge
Guest Editors

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Keywords

  • organometallic chemistry
  • homogeneous catalysis
  • synergistic effects
  • transition metal chemistry
  • main group chemistry

Published Papers (8 papers)

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Editorial

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3 pages, 627 KiB  
Editorial
Synergy between Main Group and Transition Metal Chemistry
by Stephen M. Mansell
Inorganics 2023, 11(3), 98; https://doi.org/10.3390/inorganics11030098 - 28 Feb 2023
Viewed by 1504
Abstract
Since the pioneering studies of Alfred Werner at the beginning of the 20th Century [...] Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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Research

Jump to: Editorial

11 pages, 2644 KiB  
Communication
Synthesis and Structural Comparisons of NHC-Alanes
by Fáinché Murphy, Alan R. Kennedy and Catherine E. Weetman
Inorganics 2023, 11(1), 13; https://doi.org/10.3390/inorganics11010013 - 26 Dec 2022
Cited by 2 | Viewed by 1650
Abstract
N-heterocyclic carbenes (NHCs) are widely used in organometallic chemistry. Here, we examine the role of NHCs in the stabilisation of aluminium hydrides, AlH3, also known as alanes. This includes an assessment of the various synthetic strategies, comparisons of structural parameters [...] Read more.
N-heterocyclic carbenes (NHCs) are widely used in organometallic chemistry. Here, we examine the role of NHCs in the stabilisation of aluminium hydrides, AlH3, also known as alanes. This includes an assessment of the various synthetic strategies, comparisons of structural parameters and theoretical insight. Based on percent buried volume (%Vbur) parameters, we report the largest and smallest NHC alanes to date, with noted differences in their observed stability in both the solution and solid state. Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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24 pages, 4019 KiB  
Article
Structural Study of Model Rhodium(I) Carbonylation Catalysts Activated by Indole-2-/Indoline-2-Carboxylate Bidentate Ligands and Kinetics of Iodomethane Oxidative Addition
by Mohammed A. E. Elmakki, Orbett Teboho Alexander, Gertruida J. S. Venter, Johan Andries Venter and Andreas Roodt
Inorganics 2022, 10(12), 251; https://doi.org/10.3390/inorganics10120251 - 08 Dec 2022
Cited by 4 | Viewed by 1319
Abstract
The rigid-backbone bidentate ligands Indoline-2-carboxylic acid (IndoliH) and Indole-2-carboxylic acid (IndolH) were evaluated for rhodium(I). IndoliH formed [Rh(Indoli)(CO)(PPh3)] (A2), while IndolH yielded the novel dinuclear [Rh1(Indol’)(CO)(PPh3)Rh2(CO)(PPh3)2] (B2) [...] Read more.
The rigid-backbone bidentate ligands Indoline-2-carboxylic acid (IndoliH) and Indole-2-carboxylic acid (IndolH) were evaluated for rhodium(I). IndoliH formed [Rh(Indoli)(CO)(PPh3)] (A2), while IndolH yielded the novel dinuclear [Rh1(Indol’)(CO)(PPh3)Rh2(CO)(PPh3)2] (B2) complex (Indol’ = Indol2−), which were characterized by SCXRD. In B2, the Rh1(I) fragment [Rh1(Indol’)(CO)(PPh3)] (bidentate N,O-Indol) exhibits a square-planar geometry, while Rh2(I) shows a ‘Vaska’-type trans-[O-Rh2(PPh3)2(CO)] configuration (bridging the carboxylate ‘oxo’ O atom of Indol2−). The oxidative addition of MeI to A2 and B2 via time-resolved FT-IR, NMR, and UV/Vis analyses indicated only Rh(III)-alkyl species (A3/B3) as products (no migratory insertion). Variable temperature kinetics confirmed an associative mechanism for A2 via an equilibrium-based pathway (ΔH = (21 ± 1) kJ mol−1; ΔS = (−209 ± 4) J K−1mol−1), with a smaller contribution from a reverse reductive elimination/solvent pathway. The dinuclear complex B2 showed the oxidative addition of MeI only at Rh1(I), which formed a Rh(III)-alkyl, but cleaved the bridged Rh2(I) site, yielding trans-[RhI(PPh3)2(I)(CO)] (5B) as a secondary product. A significantly smaller negative activation entropy [ΔH = (73.0 ± 1.2) kJ mol−1; ΔS = (−21 ± 4) J K−1mol−1] via a more complex/potential interchange mechanism (the contribution of ΔS to the Gibbs free energy of activation, ΔG, only ±10%) was inferred, contrary to the entropy-driven oxidative addition of MeI to A2 (the contribution of ΔS to ΔG ± 75%). Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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10 pages, 1515 KiB  
Article
Digold Phosphinine Complexes Are Stable with a Bis(Phosphinine) Ligand but Not with a 2-Phosphinophosphinine
by Peter A. Cleaves, Ben Gourlay, Margot Marseglia, Daniel J. Ward and Stephen M. Mansell
Inorganics 2022, 10(11), 203; https://doi.org/10.3390/inorganics10110203 - 11 Nov 2022
Cited by 1 | Viewed by 1411
Abstract
The reaction of [bis{3-methyl-6-(trimethylsilyl)phosphinine-2-yl}dimethylsilane] (19) with one and two equivalents of [AuCl(tht)] was attempted in order to selectively form the mono and digold species, respectively. The digold species [(AuCl)2(19)] (21) was synthesized in 32% yield [...] Read more.
The reaction of [bis{3-methyl-6-(trimethylsilyl)phosphinine-2-yl}dimethylsilane] (19) with one and two equivalents of [AuCl(tht)] was attempted in order to selectively form the mono and digold species, respectively. The digold species [(AuCl)2(19)] (21) was synthesized in 32% yield and comprehensibly characterized (multinuclear NMR spectroscopy, elemental analysis, mass spectrometry and single-crystal X-ray diffraction). The monogold species showed no 31P nuclear magnetic resonance at 25 °C but two resonances at −70 °C due to rapid exchange of AuCl between the phosphinine donors at 25 °C and was also susceptible to redistribution reactions to form the digold species. Analogous reactions of [AuCl(tht)] with 2-diphenylphosphino-3-methyl-6-trimethylsilylphosphinine (22) revealed preferential coordination of the AuCl unit to the PPh2 donor first, with coordination to the phosphinine achieved upon reaction with the second equivalent of [AuCl(tht)]. Unexpectedly, the digold complex was not stable, undergoing decomposition to give an unidentified black precipitate. Structural information could only be obtained on the digold hydrolysis product [(AuCl)2(1-OH-2-PPh2-3-MePC5H4)], which showed an aurophilic interaction. Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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25 pages, 5241 KiB  
Article
Synthesis, Single Crystal X-ray Structure, Spectroscopy and Substitution Behavior of Niobium(V) Complexes Activated by Chloranilate as Bidentate Ligand
by Alebel Nibret Belay, Johan Andries Venter, Orbett Teboho Alexander and Andreas Roodt
Inorganics 2022, 10(10), 166; https://doi.org/10.3390/inorganics10100166 - 03 Oct 2022
Cited by 1 | Viewed by 1515
Abstract
Chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone, caH2) as a bidentate ligand for Nb(V) as a metal center is presented. The different coordination behavior of caH2 is well illustrated by a monomeric (Et4N)cis-[NbO(ca)2(H2O)OPPh3]·3H2 [...] Read more.
Chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone, caH2) as a bidentate ligand for Nb(V) as a metal center is presented. The different coordination behavior of caH2 is well illustrated by a monomeric (Et4N)cis-[NbO(ca)2(H2O)OPPh3]·3H2O.THF (5) and a novel tetranuclear compound (Et4N)4[Nb4O4(ca)2(μ2-O)2Cl8]·2CH3CN (6) via self-assembly, respectively. These were obtained in >80% yields and characterized by IR, UV/Vis and NMR (1H, 13C{1H}, 31P{1H}) spectroscopy and single crystal X-ray diffraction, and they included a systematic assessment of the solid-state behavior. The anionic metal complexes showed different coordination modes at the Nb(V): [Nb4O4(ca)2(μ2-O)2Cl8]4− (6a; distorted octahedral) and cis-[NbO(ca)2(H2O)(OPPh3)] (5a; D5h distorted pentagonal bipyramidal), respectively. The tetranuclear complex 6a is substitution inert, while cis-[NbO(ca)2(H2O)OPPh3] (5a) allowed a systematic ligation kinetic evaluation. The substitution of the coordinated triphenylphosphine oxide by a range of pyridine-type entering nucleophiles, 4-N,N-dimethyl-aminopyridine (DMAP), pyridine (py), 4-methylpyridine (4Mepy), 3-chloropyridine (3Clpy) and 3-bromopyridine (3Brpy) in acetonitrile at 31.2 °C was carefully evaluated. The subtle interplay between the main group ligand systems and the hard, early transition metal Nb(V) complex (5a) was well illustrated. The entering monodentate ligands showed a 15-fold reactivity range increase in the order 3Brpy < 3Clpy < 4Mepy < py < DMAP in broad agreement with the Brønsted-donating ability of the nucleophiles. The activation parameters determined for the reaction of 5a with DMAP as the entering ligand yielded ΔHkf = 52 ± 1 kJ mol−1 and ΔSkf = −108 ± 3 J K−1 mol−1 for the enthalpy and entropy of activation, respectively, indicating an associative substitution mechanism. The study presents an important contribution to the structure/reactivity relationships in Nb(V) complexes stabilized by chloranilic acid as a bidentate ligand. Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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10 pages, 4143 KiB  
Communication
Reactivity and Stability of a Ring-Expanded N-Heterocyclic Carbene Copper(I) Boryl Imidinate
by Rex S. C. Charman, Thomas M. Horsley Downie, Thomas H. Jerome, Mary F. Mahon and David J. Liptrot
Inorganics 2022, 10(9), 135; https://doi.org/10.3390/inorganics10090135 - 07 Sep 2022
Cited by 3 | Viewed by 1548
Abstract
Frustrated Lewis pairs (FLPs) have evolved from a revolutionary concept to widely applied catalysts. We recently reported the ring-expanded N-heterocyclic carbene supported copper(I) boryliminomethanide, (6-Dipp)CuC(=NtBu)Bpin and noted it reacted with heterocumulenes in a fashion reminiscent of FLPs. We thus set out [...] Read more.
Frustrated Lewis pairs (FLPs) have evolved from a revolutionary concept to widely applied catalysts. We recently reported the ring-expanded N-heterocyclic carbene supported copper(I) boryliminomethanide, (6-Dipp)CuC(=NtBu)Bpin and noted it reacted with heterocumulenes in a fashion reminiscent of FLPs. We thus set out to explore its reactivity with a range of other substrates known to react with FLPs. This was undertaken by a series of synthetic studies using NMR spectroscopy, mass spectrometry, IR spectroscopy, and single crystal X-ray crystallography. (6-Dipp)CuC(=NtBu)Bpin was investigated for its reactivity towards water, hydrogen, and phenylacetylene. Its solution stability was also explored. Upon heating, (6-Dipp)CuC(=NtBu)Bpin decomposed to (6-Dipp)CuCN, which was characterised by SC-XRD and NMR spectroscopy, and pinBtBu. Although no reaction was observed with hydrogen, (6-Dipp)CuC(=NtBu)Bpin reacted with water to form (6-Dipp)CuC(=N(H)tBu)B(OH)pin, which was structurally characterised. In contrast to its FLP-reminiscent heterolytic cleavage reactivity towards water, (6-Dipp)CuC(=NtBu)Bpin acted as a Brønsted base towards phenyl acetylene generating (6-Dipp)CuCCPh, which was characterised by SC-XRD, IR, and NMR spectroscopy, and HC(=NtBu)Bpin Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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18 pages, 4970 KiB  
Article
N-O Ligand Supported Stannylenes: Preparation, Crystal, and Molecular Structures
by Hannah S. I. Sullivan, Andrew J. Straiton, Gabriele Kociok-Köhn and Andrew L. Johnson
Inorganics 2022, 10(9), 129; https://doi.org/10.3390/inorganics10090129 - 31 Aug 2022
Cited by 2 | Viewed by 2143
Abstract
A new series of tin(II) complexes (1, 2, 4, and 5) were successfully synthesized by employing hydroxy functionalized pyridine ligands, specifically 2-hydroxypyridine (hpH), 8-hydroxyquinoline (hqH), and 10-hydroxybenzo[h]quinoline (hbqH) as stabilizing ligands. Complexes [Sn(μ-κ2ON-OC5H4 [...] Read more.
A new series of tin(II) complexes (1, 2, 4, and 5) were successfully synthesized by employing hydroxy functionalized pyridine ligands, specifically 2-hydroxypyridine (hpH), 8-hydroxyquinoline (hqH), and 10-hydroxybenzo[h]quinoline (hbqH) as stabilizing ligands. Complexes [Sn(μ-κ2ON-OC5H4N)(N{SiMe3}2)]2 (1) and [Sn4(μ-κ2ON-OC5H4N)61O-OC5H4N)2] (2) are the first structurally characterized examples of tin(II) oxypyridinato complexes exhibiting {Sn2(OCN)2} heterocyclic cores. As part of our study, 1H DOSY NMR experiments were undertaken using an external calibration curve (ECC) approach, with temperature-independent normalized diffusion coefficients, to determine the nature of oligomerisation of 2 in solution. An experimentally determined diffusion coefficient (298 K) of 6.87 × 10−10 m2 s−1 corresponds to a hydrodynamic radius of Ca. 4.95 Å. This is consistent with the observation of an averaged hydrodynamic radii and equilibria between dimeric [Sn{hp}2]2 and tetrameric [Sn{hp}2]4 species at 298 K. Testing this hypothesis, 1H DOSY NMR experiments were undertaken at regular intervals between 298 K–348 K and show a clear change in the calculated hydrodynamic radii form 4.95 Å (298 K) to 4.35 Å (348 K) consistent with a tetramer ⇄ dimer equilibria which lies towards the dimeric species at higher temperatures. Using these data, thermodynamic parameters for the equilibrium (ΔH° = 70.4 (±9.22) kJ mol−1, ΔS° = 259 (±29.5) J K−1 mol−1 and ΔG°298 = −6.97 (±12.7) kJ mol−1) were calculated. In the course of our studies, the Sn(II) oxo cluster, [Sn6(m3-O)6(OR)4:{Sn(II)(OR)2}2] (3) (R = C5H4N) was serendipitously isolated, and its molecular structure was determined by single-crystal X-ray diffraction analysis. However, attempts to characterise the complex by multinuclear NMR spectroscopy were thwarted by solubility issues, and attempts to synthesise 3 on a larger scale were unsuccessful. In contrast to the oligomeric structures observed for 1 and 2, single-crystal X-ray diffraction studies unambiguously establish the monomeric 4-coordinate solid-state structures of [Sn(κ2ON-OC9H6N)2)] (4) and [Sn(κ2ON-OC13H8N)2)] (5). Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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16 pages, 3687 KiB  
Article
Fluoro-Germanium (IV) Cations with Neutral Co-Ligands—Synthesis, Properties and Comparison with Neutral GeF4 Adducts
by Madeleine S. Woodward, Rhys P. King, Robert D. Bannister, Julian Grigg, Graeme McRobbie, William Levason and Gillian Reid
Inorganics 2022, 10(8), 107; https://doi.org/10.3390/inorganics10080107 - 27 Jul 2022
Cited by 4 | Viewed by 1904
Abstract
The reaction of [GeF4L2], L = dmso (Me2SO), dmf (Me2NCHO), py (pyridine), pyNO (pyridine-N-oxide), OPPh3, OPMe3, with Me3SiO3SCF3 (TMSOTf) and monodentate ligands, L, in a 1:1:1 [...] Read more.
The reaction of [GeF4L2], L = dmso (Me2SO), dmf (Me2NCHO), py (pyridine), pyNO (pyridine-N-oxide), OPPh3, OPMe3, with Me3SiO3SCF3 (TMSOTf) and monodentate ligands, L, in a 1:1:1 molar ratio in anhydrous CH2Cl2 formed the monocations [GeF3L3][OTf]. These rare trifluoro-germanium (IV) cations were characterised by microanalysis, IR, 1H, 19F{1H} and, where appropriate, 31P{1H} NMR spectroscopy. The 19F{1H} NMR data show that in CH3NO2 solution the complexes exist as a mixture of mer and fac isomers, with the mer isomer invariably having the higher abundance. The X-ray structure of mer-[GeF3(OPPh3)3][OTf] is also reported. The attempts to remove a second fluoride using a further equivalent of TMSOTf and L were mostly unsuccessful, although a mixture of [GeF2(OAsPh3)4][OTf]2 and [GeF3(OAsPh3)3][OTf] was obtained using excess TMSOTf and OAsPh3. The reaction of [GeF4(MeCN)2] with TMSOTf in CH2Cl2 solution, followed by the addition of 2,2′:6′,2”-terpyridine (terpy) formed mer-[GeF3(terpy)][OTf], whilst a similar reaction with 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3-tacn) in MeCN solution produced fac-[GeF3(Me3-tacn)][OTf]. Dicationic complexes bearing the GeF22+ fragment were isolated using the tetra-aza macrocycles, 1,4,7,10-tetramethyl-1,4,7,10-tetra-azacyclododecane (Me4-cyclen) and 1,4,8,11-tetramethyl-1,4,8,11-tetra-azacyclotetradecane (Me4-cyclam), which reacted with [GeF4(MeCN)2] and two equivalents of TMSOTf to cleanly form the dicationic difluoride salts, cis-[GeF2(Me4-cyclen)][OTf]2 and trans-[GeF2(Me4-cyclam)][OTf]2. The 19F{1H} NMR spectroscopy shows that in CH3NO2 solution there are four stereoisomers present for trans-[GeF2(Me4-cyclam)][OTf]2, whereas the smaller ring-size of Me4-cyclen accounts for the formation of only cis-[GeF2(Me4-cyclen)][OTf], and is confirmed crystallographically. New spectroscopic data are also reported for [GeF4(L)2] (L = dmso, dmf and pyNO). Density functional theory calculations were used to probe the effect on the bonding as fluoride ligands were sequentially removed from the germanium centre in the OPMe3 complexes. Full article
(This article belongs to the Special Issue Synergy between Main Group and Transition Metal Chemistry)
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