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Group II Metal Complexes of the Germylidendiide Dianion Radical and Germylidenide Anion
Author(s) -
Chia SiewPeng,
Carter Emma,
Xi HongWei,
Li Yongxin,
So CheukWai
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201404357
Subject(s) - chemistry , delocalized electron , electron paramagnetic resonance , germanium , lone pair , one electron reduction , ligand (biochemistry) , crystallography , main group element , metal , radical , medicinal chemistry , derivative (finance) , magnesium , radical ion , group (periodic table) , ion , stereochemistry , molecule , transition metal , organic chemistry , biochemistry , physics , receptor , silicon , financial economics , economics , electrochemistry , catalysis , electrode , nuclear magnetic resonance
The two‐electron reduction of a Group 14‐element(I) complex [RË⋅] (E=Ge, R=supporting ligand) to form a novel low‐valent dianion radical with the composition [RË:] . 2− is reported. The reaction of [LGeCl] ( 1 , L=2,6‐(CHNAr) 2 C 6 H 3 , Ar=2,6‐ i Pr 2 C 6 H 3 ) with excess calcium in THF at room temperature afforded the germylidenediide dianion radical complex [LGe] . 2− ⋅Ca(THF) 3 2+ ( 2 ). The reaction proceeds through the formation of the germanium(I) radical [LGe⋅], which then undergoes a two‐electron reduction with calcium to form 2 . EPR spectroscopy, X‐ray crystallography, and theoretical studies show that the germanium center in 2 has two lone pairs of electrons and the radical is delocalized over the germanium‐containing heterocycle. In contrast, the magnesium derivative of the germylidendiide dianion radical is unstable and undergoes dimerization with concurrent dearomatization to form the germylidenide anion complex [C 6 H 3 ‐2‐{C(H)NAr}Ge‐Mg‐6‐{C(H)‐NAr}] 2 ( 3 ).