Reactivity of Monomeric N→Ge Coordinated Germanium(II) Hydrides

Monomeric organogermanium(II) hydrides {(LGeH)M(CO) 5 } (M = Cr ( 1 ), W ( 2 ), L = [2‐(CH 2 NEt 2 )‐4,6‐ t Bu 2 ‐C 6 H 2 ] – ) were treated with ortho ‐quinones and terminal alkyne HC≡CCO 2 Me to give {[(L H )Ge(κ 2 ‐O 2 ‐3,5‐ t Bu 2 C 6 H 2 )]M(CO) 5 } (M = Cr ( 3 ), W ( 4 )), {[(L H )Ge(κ 2 ‐O 2 ‐3,4,5,6‐Cl 4 C 6 )]M(CO) 5 } (M = Cr ( 5 ), W ( 6 )) and {[LGeCH=CH(COOMe)]Cr(CO) 5 } ( 11 ). These reactions proceeded as catalyst‐free reductions of C=O and C≡C bonds. Experimental data demonstrated zwitterionic character of Ge(II) complexes 3–6 , where the 1,3,2‐benzodioxagermylenolato anion involving the GeO 2 C 2 five membered ring coordinates the M(CO) 5 fragment. This anionic part is compensated by the N H Et 2 counter cation that is part of ligand L. Reactions of 1 and 2 differ mutually in the case of reduction of HC≡CCO 2 Me. The experimental and theoretical data suggest that compound 1 reacts with HC≡CCO 2 Me to give vinyl germylene 11 as the product of the anti‐Markovnikov cis ‐1,2‐addition, while complex 2 is inactive. These results thus suggest that the reactivity of the terminal Ge H bond may be tuned by its coordination to various transition metals.