Trialkylphosphine-Stabilized Copper(I) Gallium(III) Phenylchalcogenolate Complexes: Crystal Structures and Generation of Ternary Semiconductors by Thermolysis

A series of organometallic trialkylphosphine-stabilized copper gallium phenylchalcogenolate complexes [(R3P)mCunMe2–xGa­(EPh)n+x+1] (R = Me, Et, iPr, tBu; E = S, Se, Te; x = 0, 1) has been prepared and structurally characterized by X-ray diffraction. From their molecular structures three groups of compounds can be distinguished: ionic compounds, ring systems, and cage structures. All these complexes contain one gallium atom bound to one or two methyl groups, whereas the number of copper atoms, and therefore the nuclearity of the complexes, is variable and depends mainly on size and amount of phosphine ligand used in synthesis. The Ga–E bonds are relatively rigid, in contrast to flexible Cu–E bonds. The lengths of the latter are controlled by the coordination number and steric influences. The Ga–E bond lengths depend systematically on the number of methyl groups bound to the gallium atom, with somewhat shorter bonds in monomethyl compounds compared to dimethyl compounds. Quantum chemical computations reproduce this trend and show furthermore that the rotation of one phenyl group around the Ga–E bond is a low energy process with two distinct minima, corresponding to two different conformations found experimentally. Mixtures of different types of chalcogen atoms on molecular scale are possible, and then ligand exchange reactions in solution lead to mixed site occupation. In thermogravimetric studies the complexes were converted into the ternary semiconductors CuGaE2. The thermolysis reaction is completed at temperatures between 250 and 400 °C, typically with lower temperatures for the heavier chalcogens. Because of significant release of Me3Ga during the thermolysis process, and especially in case of copper excess in the precursor complexes, binary copper chalcogenides are obtained as additional thermolysis products. Quaternary semiconductors can be obtained from mixed chalcogen precursors

Trialkylphosphine-Stabilized Copper(I) Gallium(III) Phenylchalcogenolate Complexes: Crystal Structures and Generation of Ternary Semiconductors by Thermolysis

A series of organometallic trialkylphosphine-stabilized copper gallium phenylchalcogenolate complexes [(R₃P)<i>_m</i>Cu<i>_n</i>Me_2–<i>x</i>Ga­(EPh)_{<i>n</i>+<i>x</i>+1}] (R = Me, Et, ⁱPr, ^tBu; E = S, Se, Te; <i>x</i> = 0, 1) has been prepared and structurally characterized by X-ray diffraction. From their molecular structures three groups of compounds can be distinguished: ionic compounds, ring systems, and cage structures. All these complexes contain one gallium atom bound to one or two methyl groups, whereas the number of copper atoms, and therefore the nuclearity of the complexes, is variable and depends mainly on size and amount of phosphine ligand used in synthesis. The Ga–E bonds are relatively rigid, in contrast to flexible Cu–E bonds. The lengths of the latter are controlled by the coordination number and steric influences. The Ga–E bond lengths depend systematically on the number of methyl groups bound to the gallium atom, with somewhat shorter bonds in monomethyl compounds compared to dimethyl compounds. Quantum chemical computations reproduce this trend and show furthermore that the rotation of one phenyl group around the Ga–E bond is a low energy process with two distinct minima, corresponding to two different conformations found experimentally. Mixtures of different types of chalcogen atoms on molecular scale are possible, and then ligand exchange reactions in solution lead to mixed site occupation. In thermogravimetric studies the complexes were converted into the ternary semiconductors CuGaE₂. The thermolysis reaction is completed at temperatures between 250 and 400 °C, typically with lower temperatures for the heavier chalcogens. Because of significant release of Me₃Ga during the thermolysis process, and especially in case of copper excess in the precursor complexes, binary copper chalcogenides are obtained as additional thermolysis products. Quaternary semiconductors can be obtained from mixed chalcogen precursors

Integration of Electron Density and Molecular Orbital Techniques to Reveal Questionable Bonds: The Test Case of the Direct Fe−Fe Bond in Fe₂(CO)₉

The article illustrates the advantages of partitioning the total electron density ρ(rb), its Laplacian ∇2ρ(rb), and the energy density H(rb) in terms of orbital components. By calculating the contributions of the mathematically constructed molecular orbitals to the measurable electron density, it is possible to quantify the bonding or antibonding character of each MO. This strategy is exploited to review the controversial existence of direct Fe−Fe bonding in the triply bridged Fe2(CO)9 system. Although the bond is predicted by electron counting rules, the interaction between the two pseudo-octahedral metal centers can be repulsive because of their fully occupied t2g sets. Moreover, previous atoms in molecules (AIM) studies failed to show a Fe−Fe bond critical point (bcp). The present electron density orbital partitioning (EDOP) analysis shows that one σ bonding combination of the t2g levels is not totally overcome by the corresponding σ* MO, which is partially delocalized over the bridging carbonyls. This suggests the existence of some, albeit weak, direct Fe−Fe bonding

Trialkylphosphine-Stabilized Copper(I) Phenylchalcogenolate Complexes - Crystal Structures and Copper–Chalcogenolate Bonding

A series of trialkylphosphine-stabilized copper(I) phenylchalcogenolate complexes [(R3P)m(CuEPh)n] (R = Me, Et, iPr, tBu; E = S, Se, Te) has been prepared and structurally characterized by X-ray diffraction. Structures were found to be mono-, di-, tri-, tetra-, hexa-, hepta-, or decanuclear, depending mainly on size and amount of phosphine ligand. Several structural details were observed, including unusually long Cu–E bonds or secondary Cu--E connections, μ4-bridging, and planar bridging chalcogenolate ligands. Relatively rigid Cu–E–C angles were found to be of significant influence on the flexible molecular structures, especially for bridging chalcogenolate ligands, since in these cases a correlation results between the Cu–E–Cu angles and the inclination of the E–C bonds to their Cu–E–Cu planes. We further address some of these phenomena by means of density functional computations

Trialkylphosphine-Stabilized Copper(I) Phenylchalcogenolate Complexes - Crystal Structures and Copper–Chalcogenolate Bonding

A series of trialkylphosphine-stabilized copper(I) phenylchalcogenolate complexes [(R3P)m(CuEPh)n] (R = Me, Et, iPr, tBu; E = S, Se, Te) has been prepared and structurally characterized by X-ray diffraction. Structures were found to be mono-, di-, tri-, tetra-, hexa-, hepta-, or decanuclear, depending mainly on size and amount of phosphine ligand. Several structural details were observed, including unusually long Cu–E bonds or secondary Cu--E connections, μ4-bridging, and planar bridging chalcogenolate ligands. Relatively rigid Cu–E–C angles were found to be of significant influence on the flexible molecular structures, especially for bridging chalcogenolate ligands, since in these cases a correlation results between the Cu–E–Cu angles and the inclination of the E–C bonds to their Cu–E–Cu planes. We further address some of these phenomena by means of density functional computations