Synthesis and Structural Characterization of Metallogermylenes, Cp-Substituted Germylene, and a Germanium(II)-Borane Adduct from Pyridyl-1-azaallyl Germanium(II) Chloride

The reaction of [{N­(SiMe3)­C­(Ph)­C­(SiMe3)­(C5H4N-2)}­GeCl] (1) with Na­[M­(η5-C5H5)­(CO)3]·2DME (M = Mo, W) afforded the metallogermylenes [{N­(SiMe3)­C­(Ph)­C­(SiMe3)­(C5H4N-2)}­Ge-M­(η5-C5H5)­(CO)3] (M = Mo (2), W (3)). Compounds 2 and 3 have been characterized by X-ray crystallography and NMR and IR spectroscopy. Structural analyses of compounds 2 and 3 are consistent with the presence of lone-pair electrons at the germanium­(II) center. The Ge–Mo and Ge–W bond distances of 2.875(1) and 2.852(1) Å are consistent with Ge–metal single bonds. The chlorogermylene 1 was also used in the synthesis of a substituted germylene, [{N­(SiMe3)­C­(Ph)­C­(SiMe3)­(C5H4N-2)}­Ge­(η1-C5H5)] (4), by reaction with sodium cyclopentadienylide. The reaction of compound 1 with tris­(pentafluorophenyl)­borane led to the formation of a Lewis acid–base adduct, [{N­(SiMe3)­C­(Ph)­C­(SiMe3)­(C5H4N-2)}­Ge­(Cl)→B­(C6F5)3] (5).

[{N(三甲基硅基（trimethylsilyl, SiMe3）)­C(苯基（phenyl, Ph）)­C(三甲基硅基（trimethylsilyl, SiMe3）)­(2-吡啶基（2-pyridyl, C5H4N-2）)}­GeCl]（化合物1）与Na[M(η⁵-环戊二烯基（η⁵-cyclopentadienyl, η⁵-C₅H₅）)(羰基（carbonyl, CO）)₃]·2二甲氧基乙烷（dimethoxyethane, DME）（M=钼（molybdenum, Mo）、钨（tungsten, W））发生反应，得到金属锗宾（metallogermylene）类化合物[{N(三甲基硅基)­C(苯基)­C(三甲基硅基)­(2-吡啶基)}­Ge-M(η⁵-环戊二烯基)(羰基)₃]（M为Mo时记为化合物2，为W时记为化合物3）。采用X射线单晶衍射、核磁共振（Nuclear Magnetic Resonance, NMR）波谱与红外（Infrared, IR）光谱对化合物2和3进行了结构表征。结构分析结果表明，化合物2和3的二价锗（germanium(II)）中心存在孤对电子。其Ge–Mo键长（2.875(1) 埃（angstrom, Å））与Ge–W键长（2.852(1) 埃（angstrom, Å））均符合Ge-金属单键的键长特征。氯代锗宾（chlorogermylene）1还可与环戊二烯基钠发生反应，用于合成取代型锗宾[{N(三甲基硅基)­C(苯基)­C(三甲基硅基)­(2-吡啶基)}­Ge(η¹-环戊二烯基（η¹-cyclopentadienyl, η¹-C₅H₅）)]（化合物4）。化合物1与三(五氟苯基)硼（tris(pentafluorophenyl)borane）发生反应，生成了路易斯酸-碱加合物（Lewis acid-base adduct）[{N(三甲基硅基)­C(苯基)­C(三甲基硅基)­(2-吡啶基)}­Ge(Cl)→B(C₆F₅)₃]（化合物5）。