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

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posted on 07.07.2017, 00:00 authored by Xiaohua Lu, Hecong Cheng, Yinfeng Meng, Xinmiao Wang, Lei Hou, Zhen Wang, Sanping Chen, Yaoyu Wang, Gengwen Tan, Anyang Li, Wenyuan Wang
Using the new β-diketimine 1a (PhCH­(PhCN-Dip)2, Dip = 2,6-iPr2C6H3), which possesses three phenyl groups at the ligand backbone, we synthesized the β-diketiminato germylene chloride 2 (LGeCl, L = [PhC­(PhCN-Dip)2]). The β-diketiminato germanium radical complex 3 (LGe:, L = [PhC­(PhCN-Dip)2]2–) has been isolated by reduction of LGeCl 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:, L′ = [HC­(tBuCN-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 π-antibonding orbital between the N and C atoms. This results in ca. 0.14 Å shorter N–Ge bonds and ca. 0.1 Å 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.