A Bis(silylenyl)pyridine Zero-Valent Germanium Complex and Its Remarkable Reactivity.

The synthesis, reactivity, and electronic structure of the unique germylone iron carbonyl complex [SiNSi]Ge0 →Fe(CO)4 is reported. The compound was obtained in 49 % yield from the reaction of the bis(N-heterocyclic silylenyl)pyridine pincer ligand SiNSi (1,6-C5 NH3 -[EtNSi(Nt Bu)2 CPh]2 ) with GeCl2 ⋅(dioxane) to give the corresponding chlorogermyliumylidene chloride precursor [SiNSi]GeII Cl+  Cl- , which was further reduced with K2 Fe(CO)4 . Single-crystal X-ray diffraction analysis of [SiNSi]Ge→Fe(CO)4 revealed that the Ge0 center adopts a trigonal-pyramidal geometry with a Si-Ge-Si angle of 95.66(2)°. Remarkably, one of the SiII donor atoms in the complex is five-coordinated because of additional (pyridine)N→Si coordination. Unexpectedly, the reaction of [SiNSi]Ge→Fe(CO)4 with GeCl2 ⋅(dioxane) (one molar equivalent) yielded the first push-pull germylone-germylene donor-acceptor complex, [SiNSi]Ge→GeCl2 →Fe(CO)4 through the insertion of GeCl2 into the dative Ge0 →Fe bond. The electronic features of the new compounds were investigated by DFT calculations.