A Two-Coordinate Neutral Germylene Supported by a Β-Diketiminate Ligand in the Radical State

Using the new beta-diketimine la (PhCH(PhC= N-Dip)(2), Dip = 2,6-'Pr2C6H3), which possesses three phenyl groups at the ligand backbone, we synthesized the beta-diketiminato germylene chloride 2 (LGeCl, L = [PhC(PhCN-Dip)(2)](-)). The beta-diketiminato germanium radical complex 3 ((LGe)-L-center dot:, L-center dot = (center dot)[PhC(PhCN-Dip)(2)](2-)) has been 1 isolated by reduction of LGeCI with sodium/naphthalene in 64% yield. X-ray diffraction, HR-MS, and electron paramagnetic resonance analyses together with DFT calculations reveal that 3 exhibits a remarkably different structure in comparison with the reported Ge(I) radical C (L'Ge-center dot:, L' = [HC((BuCN)-Bu-t-Dip)(2)](-)). The inductive effect of three phenyl groups leads to the backbone of ligand 1 being more electron deficient, and therefore the singly occupied molecular orbital (SOMO) of radical 3 is mainly composed of a pi-antibonding orbital between the N and C atoms. This results in ca. 0.14 angstrom shorter N-Ge bonds and ca. 0.1 angstrom longer C-N bonds in 3 in comparison to those observed in C. Thus, the radical 3 is a two-coordinate germylene stabilized by an N-heterocyclic radical ligand.