Synthesis of cationic germyleneiron complexes and X-ray structure of [Cp*CO₂Fe=GeMe₂·DMAP]BPh ₄·CH₃CN (Cp* = C₅Me₅, DMAP = 4-(dimethylamino)pyridine)

Chlorogermyliron complexes Cp*(CO)₂FeGeMe₂Cl (1) and Cp*CO)(PPh₃)FeGeMe₂Cl (2) undergo chloride abstraction by AgBPh₄ in the presence of 4-(dimethylamino)pyridine (DMAP) to afford cationic germylene complexes [Cp*(CO)₂Fe=GeMe₂·DMAP]BPh₄ (3) and [Cp*(CO)(PPh₃)Fe=GeMe₂-DMAP]BPh₄ (4), respectively. Structural determination by X-ray crystallography of 1 and 3·CH₃CN revealed that both complexes have a gauche conformation with respect to the Fe - Ge bonds. The short Fe - Ge bond (2.329(3) Å) and very long Ge - N (DMAP) bond (1.989(8) Å) in 3·CH₃CN demonstrate the unsaturated bond character of the former and the dative bond character of the latter. The complexes 3 and 4 in dichloromethane revert to the parent complexes 1 and 2, respectively, via an electron-transfer process from the counteranion, BPh₄^-, followed by chlorine abstraction from the solvent.