Ge–Cu-Complexes Ph(pyO)Ge(μ2-pyO)2CuCl and PhGe(μ2-pyO)4CuCl—Representatives of Cu(I)Ge(IV) and Cu(II)Ge(IV) Dative Bond Systems

Phenylgermaniumpyridine-2-olate PhGe(pyO)3 (compound 1Ge) and CuCl react with the formation of heteronuclear complex Ph(pyO)Ge(μ2-pyO)2CuCl (2Ge’) rather than forming expected compound PhGe(μ2-pyO)3CuCl (2Ge). Single-point calculations (at B2T-PLYP level) optimized molecular structures confirmed relative stability isomer 2Ge’ over 2Ge and, for related silicon congeners, 2Si 2Si’. Decomposition a solution upon access to air provided some crystals copper(II) PhGe(μ2-pyO)4CuCl (3Ge). Compounds 3Ge were characterized by single-crystal X-ray diffraction analyses, Ge–Cu bonds in these compounds analyzed aid quantum chemical calculations, e.g., Natural Bond Orbital analyses (NBO), Non-Covalent Interactions descriptor (NCI), topology electron density at bond critical point using Quantum Theory Atoms-In-Molecules (QTAIM) conjunction PhSi(μ2-pyO)3CuCl (2Si), PhSi(μ2-pyO)4CuCl (3Si), as well potential isomers Ph(pyO)Si(μ2-pyO)2CuCl (2Si’) Pronounced Cu→Ge (over Cu→Si) lone pair donation was found Cu(I) compounds, whereas Cu(II) 3Si 3Ge, this σ-donation is less pronounced only marginally enhanced 3Si.