Donor–acceptor chromophores based on coordination polymers of silicon(IV) and germanium(IV)

New charge-transfer complexes with pyrazine are synthesized from germanium(IV) and silicon(IV) bis(catecholates): 36Сat2Ge, 35Cat2Ge, and 36Сat2Si (36Сat and 35Cat are 3,6- and 3,5-di-tert-butylpyrocatechol dianions, respectively). The synthesized compounds in the crystalline state are 1D coordination polymers with the octahedral environment of the complexing agent. The electronic absorption spectra of suspensions of the crystalline compounds in Nujol demonstrate an absorption in a range of 450–800 nm causing their intense color. A set of the spectral and theoretical studies indicates that the synthesized metal-organic frameworks of silicon and germanium can be considered as donor–acceptor chromophores with the photoinduced interligand charge transfer between the donor catecholate and acceptor pyrazine ligands.