Bulky Aminotroponiminate-Stabilized Germylene Monochloride and Its Alkyne Derivatives

By means of a two-step synthetic route, aminotroponimine [( t -Bu) 2 ATI]H ( 3 ) with a tert -butyl substituent on the nitrogen atoms has been synthesized from 2-(tosyloxy)tropone. Lithiation of 3 with n -BuLi in THF afforded the lithium salt [( t -Bu) 2 ATI]Li·(THF) 2 ( 4 ). Reaction of 4 with GeCl 2 ·(1,4-dioxane) resulted in the germylene monochloride complex [( t -Bu) 2 ATI]GeCl ( 5 ). Treatment of 5 with the lithium derivative of ethynyl ferrocene [(C 5 H 5 )Fe(C 5 H 4 )C≡CH] ( 6 ) and phenyl acetylene (C 6 H 5 C≡CH) ( 7 ) gave the corresponding alkynyl germylene complexes [( t -Bu) 2 ATI]GeC≡C(C 5 H 4 )Fe(C 5 H 5 ) ( 8 ) and [( t -Bu) 2 ATI]GeC≡CC 6 H 5 ( 9 ), respectively. Compounds 3, 4, 5, 8, and 9 have been characterized by elemental analysis and various spectroscopic (multinuclear NMR, mass, and IR) techniques. Further confirmation came from the single-crystal X-ray structural studies on all these compounds. The structure of the alkynyl germylenes reveals the presence of a slightly bent Ge(II)−C≡C moiety [bond angle in 8 168.4(3)° and 9 170.8(2)°].