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Communication

Monodentate Ligands in X-Cu(I)-Y Complexes—Structural Aspects

by
Milan Melník
1,*,
Veronika Mikušová
2 and
Peter Mikuš
1,3,*
1
Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovakia
2
Department of Galenic Pharmacy, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovakia
3
Toxicological and Antidoping Centre, Faculty of Pharmacy, Comenius University Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovakia
*
Authors to whom correspondence should be addressed.
Inorganics 2024, 12(11), 279; https://doi.org/10.3390/inorganics12110279
Submission received: 3 October 2024 / Revised: 24 October 2024 / Accepted: 26 October 2024 / Published: 30 October 2024
(This article belongs to the Special Issue Feature Papers in Organometallic Chemistry 2024)
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Abstract

:
This structural study examines over 102 coordinate Cu(I) complexes with compositions such as C-Cu-Y (Y=HL, OL, NL, SL, SiL, BL, PL, Cl, Br, I, AlL, or SnL), N-Cu-Y (Y=OL, Cl), S-Cu-Y (Y=Cl, Br, I), P-Cu-Y (Y=Cl, I), and Se-Cu-Y (Y=Br, I). These complexes crystallize into three different crystal classes: monoclinic (seventy-two instances), triclinic (twenty-eight instances), and orthorhombic (eight instances). The Cu-L bond length increases with the covalent radius of the ligating atom. There are two possible geometries for coordination number two: linear and bent. A total of 21 varieties of inner coordination spheres exist, categorized into two hetero-types (C-Cu-Y, i.e., organometallic compounds and X-Cu-Y, i.e., coordination compounds). The structural parameters of hetero Cu(I) complexes were compared with trans-X-Cu (I)-X (homo) complexes and analyzed. The maximum deviations from linearity (180.0°) are, on average, 10.3° for Br-Cu(I)-Br, 16.6° for C-Cu(I)-Sn, and 35.5° for P-Cu(I)-I. These results indicate that ligand properties influence deviation from linearity, increasing in the order of hard < borderline < soft.

Graphical Abstract

1. Introduction

The chemistry of copper compounds has been widely studied, with a significant focus on the relationship between their structure and reactivity, which plays a crucial role in applications ranging from industrial catalysis to biomedical fields. Most X-ray studies of transition metal compounds involve copper. While copper typically exists in the +2 oxidation state, other states, including +1, +3, and +4, are also known, with copper(I) being the most common. Although copper(I) is prone to air oxidation and unstable in aqueous solutions, many stable compounds have been synthesized using soft pi-acid ligands, and others remain stable due to their very low solubility.
It is well-established that Cu(I) and Cu(II) complexes exhibit distinct intrinsic stereochemical preferences [1]. Copper(II), with its d9 configuration, tends to adopt stereochemistries that benefit from ligand field stabilization due to energetically favorable d-orbital splitting. In contrast, copper(I), being d10, has its stereochemistry primarily influenced by steric and charge effects alone. These differences in stereochemical preferences have significant implications for copper’s role in biological redox chemistry. Blue copper proteins exemplify this by adopting a donor ligand set and stereochemistry that strike a balance between the inherent preferences of both copper(I) and copper(II) [2]. Studying the reaction chemistry of coordinatively unsaturated copper(I) complexes is key to understanding the reaction mechanism by which dioxygen-activating copper proteins function. Cuprous forms of these enzymes often exhibit two- or three-coordination [3]. Structural comparisons between copper(I) and copper(II) redox pairs have been reported with ligands like thioether [4,5,6], imidazole [7], and mixed pyridine thioether donors [8].
Structural studies of copper(I) compounds have been carried out and have been sporadically summarized in annual reports [9,10,11,12]. The structural chemistry of single halo (amine) copper(I) compounds has been reviewed [13]. A comprehensive overview of copper(I) structures (almost one thousand) was published in 1995 [14]. Recently, structures of mutually trans-X-Cu(I)-X (X=OL, NL, CL, PL, SL, Se L, Cl, or Br) were studied [15]. This manuscript aims to analyze the structural parameters of over one hundred X-Cu(I)-Y complexes, enabling us to compare them with the previously analyzed group of X-Cu(I)-X complexes. The structures are divided into two groups according to their coordination atoms: C-Cu(I)-Y and X-Cu(I)-Y, respectively.

2. Structural Aspects of C-Cu(I)-Y (Y=HL, OL, NL, SL, Si L, BL, PL, Cl, Br, I, CAl, or CSn)

2.1. Structures of C-Cu(I)-Y (Y=HL, OL)

In the monoclinic 0.55 (C22H36N+) 0.55 (C18HBF15−) 0.45 [Cu(C22H36N)(C18HBF15)] (at 100 K) [16], two unidentate ligands, in the former via C- and in the latter via H-donor atoms, form the C-Cu(I)-H type with Cu-L bond distances of 1.879 Å (L=C) and 1.769 Å (L=H). The C-Cu(I)-H bond angle is 177.0°. This is the only example of such a type.
There are 19 examples in which two unidentate ligands, via C- and O-donor atoms, form the C-Cu(I)-O type. Such Cu(I) complexes are the monoclinics [Cu(C22H35N)(CHO2)] (at 100 K) [16], [Cu(C18H20N2)(t-BuO)] (at 210 K) [17], [Cu(C28H40N2(t-BuO)] (at 150 K) [17], [Cu(C27H37N2)(C27H36N2O2)] (at 150 K) [18], [Cu(C27H36N2)(C2H3O2]0.5(C6H6) (at 193 K) [19], [Cu(C21H24N2)(C2H3O2)] (at 295 K) [20] [Cu(C27H38N2)(C2H3O2)]C6H6 (at 295 K) [20], [Cu(C27H38N2)(C2H3O2)]C7H8 (at 200 K) [21], [Cu(C21H26N2)(CF3CO2)] (at 173 K) [22], [Cu(C27H36N2)(PhCOO)] (at 100 K) [23], [Cu(C27H37N2)(C8H7O3)](C4H8O) (at 173 K) [24], [Cu(C24H28N2O2)(Ph3SiO)] (at 150 K) [25], and [Cu(C27H38N2)(C5H3SO2)] (at 100 K) [26].
The triclinics are [Cu(C23H30N2)(C4H9O)] (at 210 K) [17], [Cu(C21H26N2)(C4H9O)]0.5(C6H6) (at 150 K) [17], and [Cu(C24H35N2)(C14H13O2)]0.5(C4H8O) (at 163 K) [27].
The structure of [Cu(C24H28N2O2)(Ph3SiO)] [25] is shown in Figure 1 as an example. The total mean Cu-L bond distances in Cu(I) complexes with the C-Cu(I)-O type are 1.869 Å (range 1.844–1.886 Å) (L=C) and 1.837 Å (range 1.769–1.914 Å) (L=O). The C-Cu(I)-O bond angles range from 168.2° to 179.1° (mean 175.1°).
The [Cu(C11H20N2)(C4H9O)] (at 100 K) [27] complex crystallizes in two crystal classes, monoclinic and orthorhombic. Each Cu(I) atom has two coordinates (C-Cu(I)-O). These complexes also differ from the structural data. The Cu-L bond distances, monoclinic vs. orthorhombic, are 1.876 Å (L=C) and 1.803 Å (L=O) vs. 1.882 Å and 1.815 Å. The values of the C-Cu(I)-O bond angles are 173.7° and 175.0°, respectively.

2.2. Structures of C-Cu(I)-Y (Y=NL, SL, SiL)

There are 21 Cu(I) complexes in which monodentate ligands, one via C atom and another one via N atom, create two-coordinate Cu(I) atoms of the C-Cu(I)-N type. Such complexes are the monoclinics [Cu(C27H36N2)(py)]BF4 (at 296 K) [28], [Cu(C27H36N2)(2-CH3py)]BF4CHCl3 (at 140 K) [28], [Cu(C27H36N2)(2-Phpy)]BF4 (at 140 K) [28], [Cu(C27H38N2)(t-Bu3 P=N)]C6H14 (at 154 K) [29], [Cu(C27H36N2)(t-Bu3 P=N)]C5H12 (at 200 K) [29], [Cu(C23H35N)(C12H8N)] (at 100 K) [30], [Cu(C28H39N2)(C16H17PON)] (at 150 K) [31], [Cu(C31H38N2)(C12H8N)] (at 100 K) [32], [Cu(C27H36N2)(N3)] (at 173 K) [33], [Cu(C27H36N2)(C12H8N)] (at 180 K) [34], [Cu(C27H34N2)(C12D8N)] (at 180 K) [34], and [Cu(C19H20N2)(NCO)] (at 293 K) [35], the orthorhombics [Cu(C27H34N2)(p-tosylN4)]0.25(CH2Cl2) (at 173 K) [33], [Cu(C21H24N2)(C12H8N)] (at 180 K) [34], [Cu(C27H36N2)(NCO)] (at 123 K) [35], [Cu(C27H38N2)(NCO)] (at 123 K) [35], [Cu(C27H38N2)(NCS)] (at 123 K) [35], and [Cu(C21H24N2)(C11H10F4NO2)] (at 153 K) [36], and the triclinics [Cu(C27H9N2)(C8H7N4O)]C6H6 (at 173 K) [33], [Cu(C27H36N2)(C8H5N2O)] (at 173 K) [33], and [Cu(C11H21N2)(C37H63AlN4Si2)]0.5(C6H14) (at 150 K) [37]. The structure of [Cu(C19H20N2)(NCO)] [35] is shown in Figure 2 as an example. The total mean values of the Cu-L bond distances are 1.875 Å (range 1.862–1.928 Å) (L=C) and 1.864 Å (range 1.810–1.913 Å) (L=N) and the mean C-Cu(I)-N bond angle is 175.7° (range 166.8°–179.8°). The structure of [Cu(C23H35N)(C12H8N)] [30] is shown in Figure 3 as another illustrative example.
There are two Cu(I) complexes, the monoclinic [Cu(C69H56N2)(SH)]CH2Cl2 (at 100 K) [38] and the orthorhombic [Cu(C27H36N2)(SH)] (at 100 K) [38], in which there is an unidentate ligand via a C-donor atom with an unidentate SH form of the C-Cu(I)-S type, with mean Cu-L bond distances of 1.867 Å (L=C) and 2.104 Å (L=S). The mean C-Cu(I)-S bond angle is 177.8°.
In the monoclinics [Cu(C27H36N2)((MeO)3Si)] (at 100 K) [39], [Cu(C21H24N2)(C8H11Si)] (at 100 K) [40], [Cu(C11H20N2)(C8H11Si)]0.5C7H8 (at 100 K) [40], [Cu(C27H36N2)(C21HN3Si3)] SbF6 CH2Cl2 (at 100 K) [41], the orthorhombics [Cu(C21H24N2)(Ph3Si)] (at 100 K) [40] and [Cu(C11H20N2)(C8H11Si)] (at 100 K) [40], and the triclinic [Cu(C27H36N2)(Ph3Si)] (at 100 K) [40], unidentate ligands via C- and Si-donor atoms form the C-Cu(I)-Si type. The structure of [Cu(C27H36N2)((MeO)3Si)] [39] is shown in Figure 4 as an example. The total mean values of the Cu-L bond distances are 1.935 Å (range 1.925–1.941 Å) (L=C) and 2.273 (range 2.267–2.241 Å) (L=Si). The mean value of the C-Cu(I)-Si bond angles is 173.7 (range 168.2–178.5°).

2.3. Structures of C-Cu(I)-Y (Y=BL, PL)

There are four complexes: the monoclinics [Cu(C11H20N2)(C8H10N2B)] (at 100 K) [42] and [Cu(C27H36N2)(C5H10O2B)](C4H8O) (at 100 K) [43], the orthorhombic [Cu(C69H56N2)(C5H10O2B)] (at 100 K) [43], and the triclinic [Cu(C27H36N2)(C5H10O2B)]C7H8 (at 100 K) [43], in which unidentate ligands via C- and B-donor atoms form a C-Cu(I)-B type. The total mean values of the Cu-L bond distances are 1.939 (range 1.931–1.953 Å) (L=C) and 2.005 (range 1.993–2.020 Å) (L=B). The mean value of the C-Cu(I)-B bond angles is 173.5° (range 171.4–175.5°).
The two unidentate ligands, one via C- and another one via P-donor atom, create two-coordinate Cu(I) atoms (C-Cu(I)-Cl). There are seven complexes with such a type: the monoclinics [Cu(C27H36N2)(C6H18Si2P)]C7H8 (at 100 K) [44], [Cu(C27H40N)(C22H39N4OP)] (at 100 K) [45], [Cu(C27H36N2)(C8H23N2BP)]Et2O (at 130 K) [46], [Cu(C60H84AlN4O)(t-Bu3P)]C6H6 (at 150 K) [47], triclinic [Cu(C28H40N2)(Ph2P)] (at 150 K) [31], and [Cu(C27H36N2)(Ph2P)] (at 150 K) [31], and the orthorhombic [Cu(C24H26N2O2)(C21H24P)] (at 150 K) [47]. The structure of [Cu(C24H26N2O2)(C21H24P)] [48] is shown in Figure 5 as an example.

2.4. Structures of C-Cu(I)-Y (Y=Cl, Br, I, AlL, or SnL)

There are 16 Cu(I) complexes in which inner coordination spheres are built up by unidentate ligands via a C-donor atom with chloride (C-Cu(I)-Cl). These complexes crystalize in three crystal classes: monoclinic, orthorhombic, and triclinic. The monoclinics are [Cu(C9H16N2)(Cl)] (at 100 K) [49], [Cu(C30H42N6)(Cl)] (at 123 K) [50], [Cu(C22H33N)(Cl)] (at 100 K) [51], [Cu(C45H40N2)(Cl)] (at 123 K) [52], [Cu(C45H42N2)(Cl)] (at 193 K) [53], [Cu(C19H20N2)(Cl)] (at 293 K) [54], [Cu(C20H24N2S)(Cl)]0.5CH2Cl2 (at 100 K) [55], [Cu(C20H31N)(Cl)] (at 140 K) [56], [Cu(C21H32N4)(Cl)] (at 173 K) [57], [Cu(C30H56B11N3)(Cl)] (at 296 K) [58], [Cu(C27H43N)(Cl)] (at 100 K) [59], [Cu(C27H43N)(Cl)] (at 100 K) [60], and [Cu(C27H39N)(Cl)] (at 140 K) [60]; the orthorhombics are [Cu(C41H38N2O2)(Cl)] (at 296 K) [61] and [Cu(C27H30N2)(Cl)] (at 150 K) [62]; and the triclinics are [Cu(C55H44N2)(Cl)] CH2Cl2(at 100 K) [63], [Cu(C21H26N2O2) (Cl)] 0.25 (C4H8O) (at 150 K) [64], and [Cu(C32H31N)(Cl)] (at 100 K) [65].
The structure of [Cu(C20H24N2S)(Cl)] [55] is shown in Figure 6 as an example. The total mean values of the Cu-L bond distances are 1.883 (range 1.869–1.892 Å) (L=C) and 2.100 (range 2.088–2.177 Å) (L=Cl). The total mean value of the C-Cu(I)-P bond angle is 175.9 (range 173.3–179.4°). The structure of [Cu(C27H39N)(Cl)] (at 140 K) [60] is shown in Figure 7 as another illustrative example.
There are four monoclinic Cu(I) complexes, namely [Cu(C21H16N2)(Br)] (at 190 K) [66], [Cu(C40H4N2ClP)(Br)](CF3SO3)2(CH3CN) (at 173 K) [67], [Cu(C22H21F5N2)(Br)] (at 100 K) [68], and [Cu(C31H32N2)(Br)] (at 295 K) [69], and one triclinic, namely [Cu(C32H31N)(Br)] (at 100 K) [70], in which unidentate ligands via a C-donor atom with bromide build by two-coordinate inner spheres of C-Cu(I)-Br. The total mean values of the Cu-L bond distances are 1.892 (range 1.880–1.898 Å) (L=C) and 2.262 (range 2.216–2.268 Å) (L=Br). The total mean C-Cu(I)-Br bond angle is 174.8 (range 170.9–177.8°).
In the triclinics [Cu(C27H39N)(I)]0.5CH2Cl2 (at 140 K) [60], [Cu(C27H48N2O3Si)(I)] (at 100 K) [71], the monoclinic [Cu(C8H4N2)(I)] (at 298 K) [72], and the orthorhombic [Cu(C35H36N2)(I)] (at 133 K) [73], each unidentate ligand coordinated via a C-donor atom with iodine builds up an almost linear C-Cu(I)-I angle with a mean value of 178.9 (range 177.2–180°).
The total mean Cu-L bond distances are 1.915 (range 1.902–1.924 Å) (L=C) and 2.422 (range 2.416–2.42Å) (L=I).
There are two Cu(I) complexes, the monoclinic [Cu(C11H21N2)(C30H50N2Si2Al)](C7H14) (at 150 K) [37] and the orthorhombic [Cu(C20H31N)(C30H50N2Si2Al)] (at 150 K) [37], in which two unidentate ligands, one via C- and another one via Al-donor atoms, build up almost linear C-Cu(I)-Al with bond angles of 175.9 (±25)°. The Cu-L bond distances are 1.958 (±5) Å (L=C) and 2.374 (±29) Å (L=Al).
The monoclinic [Cu(C27H36N2)(CH3)3 Sn)] (at 100 K) [40] is the only example of the C-Cu(I)-Sn type. The Cu-L bond distances are 1.925 Å (L=C) and 2.474 Å (L=Sn) and the C-Cu(I)-Sn bond angle is 163.4°.

3. Structural Aspects of X-Cu(I)-Y (X, Y = Variable Combination of Donor Atoms)

In the monoclinic [Cu(C30H42N4)(CH3COO)] (at 213 K) [74] and triclinic [Cu(C40H58N4)(CH3COO)] (at 213 K) [74], unidentate ligands create bent geometry via N- and O-donor atoms with a mean value of the N-Cu(I)-O angles of 162.8 (±5)°. The mean values of the Cu-L bond distances are 1.852 (±2) Å (L=N) and 1.842 (±2) Å (L=O).
The monoclinic [Cu(C13H19N3O2)(Cl)] (at 130 K) [75] is the only example of the N-Cu(I)-Cl type. The N-Cu(I)-Cl bond angle is 170.6°and the Cu-L values are 1.885 Å (L=N) and 2.095 Å (L=Cl).
In two monoclinic Cu(I) complexes, [Cu(C21H24N2S)(Cl)] (at 298 K) [76] and [Cu(C27H36N2S)(Cl)] (at 100 K) [66], the united ligands via S-donor atom with chloride form a bent geometry about each Cu(I) atom (S-Cu(I)-Cl) with a value of 165.0 (±9)°. The mean values of the Cu-L bond distances are 2.139 (±9) Å (L=S) and 2.108 (±10) Å (L=Cl).
In three monoclinic Cu(I) complexes, [Cu(C21H24N2S)(Br)] (at 298 K) [76], [Cu(C27H36N2S)(Cl)] (at 100 K) [77], and [Cu(C69H56N2S)(Br)]C7H8 (at 100 K) [78], the unidentate ligands via S-donor atom with Br about each Cu(I) form a bent geometry of the S-Cu(I)-Br type. The mean values of the Cu-L bond distances are 2.134 (±18) Å (L=S) and 2.234 (±8) Å (L=Br). The monoclinic [Cu(C21H24N2S)(I)] (at 298 K) [76] is the only example of the S-Cu(I)-I type. The Cu-L bond distances are 2.142 Å (L=S) and 2.385 Å (L=I). The S-Cu(I)-I bond angle is 160.7°.
There are two monoclinic Cu(I) complexes [Cu(C21H24N2Se)(Br)] (at 298 K) [76] and [Cu(C69H56N2Se)(Br)](C7H8) (at 100 K) [78] with an inner coordination sphere of the Se-Cu(I)Br type. The mean value of the Se-Cu(I)-Br angle is 164.2 (±9)°. The mean values of the Cu-L bond distances are 2.248 (±3) Å (L=Se) and 2.230 (±4) Å (L=Br).
The monoclinic [Cu(C21H24N2Se)(I)] (at 298 K) [76] is the only example with an inner coordination sphere of Se-Cu(I)-I. The structure is shown in Figure 8. The bent geometry respects the value of 159.6°. The Cu-L bond distances are 2.252 Å (L=Se) and 2.309 Å (L=I).
The monoclinic [Cu(C40H47N2P)(Cl)]0.5(C7H8) (at 173K) has an inner coordination sphere of the P-Cu(I)-Cl type [79]. The structure of the complex is shown in Figure 9.
The value of the P-Cu(I)-Cl angle is 156.8°, and this indicates a bent geometry. The Cu-L bond distances are 2.120 Å (L=Cl) and 2.172 Å (L=P). The structure of the triclinic [Cu(C40H42N2P)(I)](C7H8) (at 173 K) [79] is similar to the chloride complex. The P-Cu-I angle is 144.5°and the Cu-L bond distances are 2.319 Å (L=I) and 2.202 Å (L=P).
The structures of [Cu(C30H42N4)(CH3COO)] (at 213 K) [74] and [Cu(C69H56N2S)(Br)]C7H8 (at 100 K) [78] are shown in Figure 10 and Figure 11, respectively, as other illustrative examples of X-Cu(I)-Y complexes possessing X, Y with variable combinations of donor atoms.

4. Conclusions

This structural study, employing Cambridge Crystallographic Database (CCDB) [80] for the analyzed structures and program Diamond [81] for creating chemical structure vizualizations, classified over one hundredtwo-coordinate copper(I) complexes. It is known that there are two geometric possibilities for coordination number two, linear and bent, respectively. The former prevails in the structure of copper(I) compounds. In general, there are two preparative procedures: (i) direct reaction of the ligand and the copper(I) atom, and (ii) electrochemistry. Most syntheses have involved direct reaction between a copper(I) halide and the appropriate ligand in a non-aqueous solvent (such as acetonitrile) under an inert atmosphere. Over 80% of the X-rays measured were made at 100 K. It is noted that copper(I) complex cations can be isolated in salts with larger anions, both organic and inorganic: ClO4, PF4, SbF6, BF4, CF3SO3, and others.
The complexes crystallized in three crystal classes: monoclinic dominates with seventy-two examples, followed by triclinic (twenty-eight examples), and orthorhombic (eight examples). In the chemistry of “soft” copper(I), a wide variety of unidentate ligating atoms form two-coordinate Cu(I) complexes.
Over all, the mean Cu(I)-L distance is observed to increase with an increasing covalent radius of the ligating atom in the sequence 1.769 Å (H, 0.31 Å) < 1.838 Å (O, 0.6 Å) < 1.863 Å (N, 0.71 Å) < 1.904 Å (C, 0.76 Å) < 2.005 Å (B, 0.86 Å) < 2.101 Å (Cl, 1.00 Å) < 2.217 Å (S, 1.02 Å) < 2.219 Å (P, 1.06 Å) < 2.254 Å (Br, 1.14 Å) < 2.273 Å (Si, 1.17 Å) < 2.374 Å (Al, 1.21 Å) < 2.386 Å (I, 1.33 Å) < 2.474 Å (Sn, 1.40 Å).
A summary of the mean Cu(I)-L bond distances from the view of trans-effect is given in Table 1 and a summary of the mean X-Cu(I)-Y angles is given in Table 2.
The trans-effect on Cu(I) distances (trans to Y) can be divided into two categories. The first, left side of Table 1, is where a hetero-donor atom Y shortens the trans-Cu (I)-X bond, and the second, right side of Table 1, in which the Y-donor atom increases the length or weakness of the trans bond. These results suggest that in the former case, there is lower transfer of donor electrons from Y to Cu(I) than in the latter case. The “soft” atoms or ligands show a larger trans-effect than the borderline or “hard” ones. There are twenty-one varieties of inner coordination spheres about the copper(I) atoms.
These varieties can be divided into C-Cu(I)-Y and X-Cu(I)-Y. When the value of the C-Cu(I)-Y angle decreases, the deviation from the linearity increases in the sequence (mean values) given in Table 2. For X-Cu(I)-Y types, the sequence (mean values) is also given in Table 2.
For the comparison, in the series of mutually trans-X-Cu (I)-X complexes [15], the sequence is (mean values): 180.0°(X=Se) > 178.2°(S) > 175.5°(O) >175.9°(Cl) > 174.5°(N) > 174.0°(C) > 172.3°(P) > 169.7°(Br).
The maximum deviations from the linearity (180.0°) are (mean values) 10.3°(Br-Cu(I)-Br) > 16.6°(C-Cu(I)-Sn) < 35.50 (P-Cu(I)-I). As can be seen, the property of the ligand’s increasing influence on deviation from linearity is in the order hard < borderline < soft.

Author Contributions

Conceptualization, M.M. and P.M.; methodology M.M. and P.M.; Writing—Original draft preparation, M.M. and P.M.; data curation, M.M.; Writing—Review and editing, V.M.; supervision, M.M. and P.M.; funding acquisition, P.M. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the project VEGA 1/0514/22, VEGA 1/0146/23 and KEGA 041UK-4/2024.

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors.

Acknowledgments

This work was supported by the Faculty of Pharmacy, Comenius University Bratislava. Structural data used in this study for discussion and calculations were obtained from Cambridge Crystallographic Database (CCDB) with an institutional license of the Slovak University of Technology in Bratislava.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

2-CH3py2-methyl pyridine
2-Phpy2-phenyl pyridine
C2H3O2acetate
C4H8Otetrahydrofuran
C5H10O2B(5,5-dimethyl-1,3,2-dioxyborinan-2-yl)
C5H3SO2(thiophene-2-carboxylate)
C6H18Si2Pbis(trimethylsilyl)phosphine
C6H23N2BPbis(diethylamino)phosphanido-borane)
C7H8toluene
C8H10N2B(1,3-dimethyl-1,3,2-benzodiazaborol-2-yl)
C8H11Sidimethyl(phenyl)silyl
C8H4N2(1,4-diisocyanobenzene)
C8H5N2O(benzoyliminomethylene amino)
C8H7N4O((4-methylphenyl)sulfonyl)carbamic azido)
C8H7O34-methoxybenzoate
C9H16N2(1,3-bis(propan-2-yl)-imidazol-2-ylidene)
C11H10F4NO2(t-butyl(2,3,5,6-tetrafluorophenyl)carbamatato)
C11H20N2(1,3-di-t-butyl-imidazol-2-ylidene)
C11H21N2(4,5-dimethyl-1,3-bis(propan-2-yl)-2,3-dihydro-1H-imidazol-2-ylidene)
C11H21N2(u-N,N-dipropan-2-ylmethylimidamide)-(4.5-dimethyl-1,3-bis(propan-2-yl)-2,3-dihydro-1H-imidazol-3-ylidene)
C12D8N(perdeutero-9H-carbazol-9-yl)(1,3-bis(2,4,6-trimethylpephonyl)imidazol-2-ylidene)
C12H8N(9H-carbazol-9-yl)
C13H19N3O2(methyl-2-((bis((dimethylamino)methylidene)amino)benzoate)
C14H13O2(4-(4-methoxyphenyl)butanoate
C16H17PON(1,1-diphenyl-N-(propan-2-yl)phosphanecarboxamidate)
C18H20N2(1,3-bis(2-methylphenyl)tetrahydropyrimiden-2-(1H)-ylidene
C18HBF15hydrido(tris(pentafluorophenyl)borate
C19H20N2(1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene)
C20H24N2S(5-(4-(methylsulfanyl)phenyl)-1,3-di-isopropylbezimidazol-2-ylidene)
C20H31N(1-(2,6-di-isopropylphenyl)-3,3′,5,5′-tetramethyl-pyrrolidin-2-ylidene)
C20H31N4,5-dimethyl-1,3-bis(propan-2-yl)-2,3-dihydro-1H-imidazol-2-ylidene)
C21H16N2(1,3-bis(3-phenylprop-2-yn-1-yl)2,3-dihydro-1H-imidazol-2-ylidene)
C21H24N2(1,3-bis(mesityl)imidazol-2-ylidene)
C21H24N2S(1,3-bis(2,4,6-trimethylphenyl)1,3-dihydro-2H-imidazol-2-thione)
C21H24N2Se(1,3-bis(2,6-(2,4,6-trimethylphenyl)1,3-dihydro-2H-imidazole-2-selone)
C21H24P(tris(4-methylyphenylphosphine)
C21H26N2(1,3-dimesitylimidazolidin-2-ylidene)
C21H32N4(1-(2-(dimethylamino)ethyl)-3-(N-(2,6-bis(propan-2-yl)phenyl)ethaniminodoyl)-2,3dihydro-1H-imidazil-2-ylidene)
C22H21F5N2(1-(2,6-di-isopropylphenyl)-3-((pentafluorophenylmethyl)imidazol-2-ylidene)
C22H33N(2-(2,6-di-isopropylphenyl)-1,4,5-trimethyl-2-azabiyclo [2.2.2]octan-3-ylidene
C22H35N(1-(2,6-di-isopropylphenyl)-3,3-diethyl-5,5-dimethylpyrolidin-2-ylidene)
C22H36N((1-(2,6-di-isopropyl)-4,4-diethyl-2,2-dimethyl-3,4-dihydro-2H-pyrrol-1-ium
C22H39N4OP(1,3-dicyclohexyl-4,6-bis(cycohexylimino)-2-oxo-1,3,5-diazaphophinan-5-yl)
C23H35N(9H-carbazol-9-yl)-2-(2,6-di-isopropylphenyl)-3,3-dimethyl-2-araspirio
C24H26N2O2(1,3-dimesilyl-5,5-dimethyl-4,6-doxohexahydropyrimidin-2-yl)
C24H28N2O2(1,3-dimesityl-5,5-dimethyl-4,6-dioxotetrahydropyrimidin-2(1H)-ylidene)
C27H30N2(1-(2,6-bis(propan-2-yl)phenyl)-3-(1-naphalen-1-yl)ethyl)2,3-dihydro-1H-imidazol-2-yl)
C27H36N2(1,3-bis(2,6-di-isopropylphenyl)imidazol-2-ylidene)
C27H36N2O2(2,3-bis(2,6-diisopropylphenyl)amino)acrylate)
C27H36N2S(1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-thione)
C27H37N2(1,3-bis(2,6-disopropylphenyl)imidazol-2-ylidene)
C27H38N2(1,3-bis(2,6-di-isopropylphenyl)-4,5-dihydroimidazol-2-ylidene)
C27H39N(1-(2,6-di-isopropylphenyl)-5,5-dimethyl-2H-spirolpyrolidine-3,2-tricyclo [3.3.1.1.3,7]decan(2-ylidene)
C27H40N(1-(2,6-diisopropylphenyl)-3,3-diethyl-5,5-dimethylpyrolidin-2-ylidene
C27H43N(2-(2,6-bis(propan-2-yl)phenyl)-3,3,9-trimethyl-6-propan-2-yl)-2-azaspiro(4,5)decan-1-ylidene
C27H46N2O3Si(1-(2,6-diisopropylphenyl)-3-(3-(trisopropoxysilyl)propyl)imidazol-2-ylidene)
C28H39N2(1,3-bis[2,6-bis(propan-2-yl)phenyl)-1,3-diazinan-2-ylidene)
C28H40N2(1,3-bis[2,6-bis(propan-2-yl)phenyl]tetrahydro-pyrimidin-2(1H)-ylidene)
C30H42N4(2-(N,N-bis(2,6-diisopropylphenyl))carbammidoyl)-1,3-dimethyl-1H-imidazol-3-iumato)
C30H42N6(4-((2-azidoethyl)(methyl)amino)-1,3-bis(2,6-di-isopropylphenyl)-2,3-dihydro-1H-imidazol-2-ilydene)
C30H49N2Si2Al((ethane-1,2-diyl)bis(N-[2,6-bis(propan-2-yl)phenyl))-1,1-dimethylsilanamino))aluminium
C30H50N2Si2Al((ethane-1,2-diyl)bis(N-[2,6-bis(popan-2-yl)phenyl)1,1-dimethylsilanamino))aluminium)
C30H56B11N3(2-(3-t-butyl-2-(2,6-di-isopropylphenyl)-1-(1,3-di-isopropyl-4,5-dimethylimidazol-2-ylidene)-2,1-azaborinyl)1,2-dicarbo-closo-dodecaboran-2-yl)
C31H32N2(2,4-dimesityl-1,2,4,5-tetrahydro-3H-naphtho[1,8-ef] [1,3]diazoein-3-ylidene)
C31H38N2(1,3-bis(2,6-bis(propan-2-yl)phenyl-2,3-dihydro-1H-benzimidazol-2-ylidene)
C32H31N(2-(2,6-bis(propan-2-yl)phenyl)-3,3-diphenyl-2,3-dihydro-1H-isoindol-1-ylidene)
C35H36N2(2,3-bis(bis(1-phenylethyl)amino)cycloprop-2-en-1-ylidene)
C37H63AlN4Si2(ethane-1,2-diyl)bis(N-[2,6-bis(propan-2-yl)phenyl]-1,1-dimethyl-silanamino)-aluminium)
C40H47N2Cl(4-chloro-1,3-bis(2,6-di-isopropylphenyl)-5-methyl(diphenylphosphono)-imidazol-2-ylidene)
C40H47N2P(2-((diphenylphosphanyl)-1,3-bis(2,6-bis(propan-2-yl)phenyl)2,3-dihydro-1H-imidazole)
C40H58N4(2-N,N-bis(2,6-diisopropylphenyl)(carbamimidoyl)-1,3-dicyclohexyl)-1H-imidazol-3-iumato)
C41H38N2O2(R,R)-(1,3-bis(8-(4-methocyphenyl)-1,2,3,4-tetrahydronaphthalen-1-yl)benzimidazol-2-ylidene)
C45H40N2(1,3-bis(2-(diphenylmethyl)-4,6-dimethyl-phenyl)-imidazol-2-ylidene)
C45H42N2(1,3-bis(2-(diphenylmethyl-4,6-dimethylphenyl)imidazolidin-2-ylidene)
C55H44N2(7,9-bis(4-(diphenylmethyl)-2,6-dimethylphenyl)-8,9-dihydro-7H-acenaphlo[1,2-d]imidazol-8-ylidene)
C60H84AlN4O(u-N-(cyclohexyl)((cyclohexyl)amino)methanidamido)-(2,7-di-t-butyl-N4,N5-bis(2,6-bis(propan-2-yl)phenyl)-9,9-dimethyl-9H-xanthene-4,5-bis(amido)aluminium)
C69H56N2(1,3-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene)
C69H56N2S(1,3-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)-1,3-dihydro-2H-imidazol-2-thione
C69H56N2Se(1,3-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)-1,3-dihydro-2H-imidazole-2-selone
CHO2formate
Ph2Pdiphenylphophido
Ph3Sitriphenylsilyl
Ph3SiOtriphenylsilanolate
PhCOObenzoate
pypyridine
t-Bu3 P=N(tri-t-butylphosphanylidene)azanide
t-Bu3Ptri-t-bitylphosphine

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Inorganics 12 00279 g001
Figure 1. Structure of [Cu(C24H28N2O2) (Ph3SiO)] [25].
Figure 1. Structure of [Cu(C24H28N2O2) (Ph3SiO)] [25].
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Inorganics 12 00279 g002
Figure 2. Structure of [Cu(C19H20N2)(NCO)] [35].
Figure 2. Structure of [Cu(C19H20N2)(NCO)] [35].
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Inorganics 12 00279 g003
Figure 3. Structure of [Cu(C23H35N)(C12H8N)] [30].
Figure 3. Structure of [Cu(C23H35N)(C12H8N)] [30].
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Inorganics 12 00279 g004
Figure 4. Structure of [Cu(C27H36N2)((MeO)3Si)] [39].
Figure 4. Structure of [Cu(C27H36N2)((MeO)3Si)] [39].
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Inorganics 12 00279 g005
Figure 5. Structure of [Cu(C24H26N2O2)(C21H24P)] [48].
Figure 5. Structure of [Cu(C24H26N2O2)(C21H24P)] [48].
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Inorganics 12 00279 g006
Figure 6. Structure of [Cu(C20H24N2S)(Cl)] [55].
Figure 6. Structure of [Cu(C20H24N2S)(Cl)] [55].
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Inorganics 12 00279 g007
Figure 7. Structure of [Cu(C27H39N)(Cl)] [60].
Figure 7. Structure of [Cu(C27H39N)(Cl)] [60].
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Inorganics 12 00279 g008
Figure 8. Structure of [Cu(C21H24N2Se)(I)] [76].
Figure 8. Structure of [Cu(C21H24N2Se)(I)] [76].
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Inorganics 12 00279 g009
Figure 9. Structure of [Cu(C40H47N2P)(Cl)] 0.5 (C7H8) [79].
Figure 9. Structure of [Cu(C40H47N2P)(Cl)] 0.5 (C7H8) [79].
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Inorganics 12 00279 g010
Figure 10. Structure of [Cu(C30H42N4)(CH3COO)] [74].
Figure 10. Structure of [Cu(C30H42N4)(CH3COO)] [74].
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Figure 11. Structure of [Cu(C69H56N2S)(Br)]C7H8 [78].
Figure 11. Structure of [Cu(C69H56N2S)(Br)]C7H8 [78].
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Table 1. A summary of the mean Cu(I)-L bond distances [Å].
Table 1. A summary of the mean Cu(I)-L bond distances [Å].
(X) a Trans to (Y) b [Å](X) Trans to (X) < [Å](X) a Trans to (Y) b [Å]
1.832 (C) < 1.848 (N)<(O), 1.849, (O)
1.852 (O) < 1.855 (Cl) < 1.864 (C)<(N), 1.886, (N)
2.095 (N) < 2.100 (C)<(Cl), 2.104, (Cl)<2.108 (S) < 2.120 (P)
2.104 (C) < 2.134 (Br)<(S), 2.137, (S)<2.139 (Cl) < 2.142 (I)
2.172 (Cl) < 2.202 (I) < 2.219 (C)<(P), 2.236, (P)
2.248 (Br) < 2.252 (I)<(Se), 2.260, (Se)
1.867 (S) < 1.869 (O) < 1.875 (N)<(C), 1.900, (C)<1.915 (I) < 1.917 (P) < 1.925 (Sn)<
1.879 (H) < 1.883 (Cl) < 1.892 (Br) <1.935 (Si) < 1.939 (B) < 1.958 (Al)
a ligand affected defined in the central column [4]. b trans-effect ligand shown in parentheses.
Table 2. A summary of the mean X-Cu(I)-Y angles.
Table 2. A summary of the mean X-Cu(I)-Y angles.
Organometalic Compounds C-Cu(I)-YCoordination Compounds X-Cu(I)-Y
178.9°(Y=I) > 177.8°(S) > 177.0°(H) > 175.9°(Al) > 175.8°(Cl) > 175.7°(N) > 175.1°(O) > 174.8°(Br) > 174.1°(P) > 173.7°(Si) > 173.5°(B) > 163.4°(Sn)170.6°(X=N; Y=Cl) > 166.2°(S, Br) > 165.8°(S, Cl) > 164.2°(Se, Br) > 162.2°(N, O) > 160.7°(S, I) > 159.6°(Se, I) > 156.8°(P, Cl) > 144.5°(P, I)
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Melník, M.; Mikušová, V.; Mikuš, P. Monodentate Ligands in X-Cu(I)-Y Complexes—Structural Aspects. Inorganics 2024, 12, 279. https://doi.org/10.3390/inorganics12110279

AMA Style

Melník M, Mikušová V, Mikuš P. Monodentate Ligands in X-Cu(I)-Y Complexes—Structural Aspects. Inorganics. 2024; 12(11):279. https://doi.org/10.3390/inorganics12110279

Chicago/Turabian Style

Melník, Milan, Veronika Mikušová, and Peter Mikuš. 2024. "Monodentate Ligands in X-Cu(I)-Y Complexes—Structural Aspects" Inorganics 12, no. 11: 279. https://doi.org/10.3390/inorganics12110279

APA Style

Melník, M., Mikušová, V., & Mikuš, P. (2024). Monodentate Ligands in X-Cu(I)-Y Complexes—Structural Aspects. Inorganics, 12(11), 279. https://doi.org/10.3390/inorganics12110279

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