Bulky Aminotroponiminate-Stabilized Germylene Monochloride and Its Alkyne Derivatives

By means of a two-step synthetic route, aminotroponimine [(t-Bu)2ATI]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)2ATI]Li·(THF)2 (4). Reaction of 4 with GeCl2·(1,4-dioxane) resulted in the germylene monochloride complex [(t-Bu)2ATI]GeCl (5). Treatment of 5 with the lithium derivative of ethynyl ferrocene [(C5H5)Fe(C5H4)CCH] (6) and phenyl acetylene (C6H5CCH) (7) gave the corresponding alkynyl germylene complexes [(t-Bu)2ATI]GeCC(C5H4)Fe(C5H5) (8) and [(t-Bu)2ATI]GeCCC6H5 (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)°].