New Insight into the Three-Coordinate Divalent Germanium Compounds L2GeΣ (L2 = PhNC(Me)CHC(Me)NPh, Σ = Cl, I, Me, OMe). Structural, Photoelectron Spectroscopic, and Theoretical Analysis
journal contributionposted on 27.06.2003, 00:00 by Isabelle Saur, Karinne Miqueu, Ghassoub Rima, Jacques Barrau, Virginie Lemierre, Anna Chrostowska, Jean-Marc Sotiropoulos, Geneviève Pfister-Guillouzo
An experimental and theoretical study of the heteroleptic divalent germanium compounds containing the bidentate coordinating monoanionic β-diketiminate ligand L2GeΣ (L2 = PhNC(Me)CHC(Me)NPh; Σ = Cl (1), I (2), Me (3), OMe (4)) has been performed in this contribution. The new stable germanium(II) compounds 3 and 4 have been synthesized by reaction of 1 with RLi (R = Me, OMe) and fully characterized. The crystal structures of 1−3 and their electronic structures have been determined by X-ray diffraction and UV-photoelectron spectroscopy (UPS), respectively. DFT calculations on 1 and 3 were carried out at the B3LYP level of theory. Natural bond orbital analysis for the model molecules 1‘ and 3‘ (without phenyl) gives information on the Ge−Σ bonding. It turns out from the NMR, mass spectroscopy, and X-ray molecular geometry properties together with the ab initio calculations that the three-coordinated germanium(II) compound L2GeX is best described by a model structure corresponding to a divalent germanium species weakly coordinated with the halide group, L2Ge+···X-. This view is confirmed by the particularly low energetic values of the X atom lone-pair ionizations.