A Dimeric Gallium Hydrazide as an Active Lewis Pair – Complexation and Activation of Me2GaH and Various Heterocumulenes |
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Authors: | Werner Uhl Matthias Willeke Alexander Hepp Damian Pleschka Marcus Layh |
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Institution: | 1. +49‐251‐8336660;2. Institut für Anorganische und Analytische Chemie, Universit?t Münster, Münster, Germany |
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Abstract: | Treatment of the dimeric gallium hydrazide Me2Ga‐N(2‐Ad)‐NC5H10]2 ( 5 ) with Me2GaH resulted in the formation of an adduct 6 by Ga–N bond cleavage and coordination of the metal hydride via a Ga–N and a 3c–2e Ga–H–Ga bond. This reaction reflects the typical behavior of frustrated Lewis pairs. Reactions with heterocumulenes R–N=C=X (R = Ph, CMe3, Dipp, X = O; R = Ph, X = S) or X=C=X (X = O, S) resulted in the formation of the cyclic Ga–N insertion products Me2Ga–N(R)C(O)N(2‐Ad)‐NC5H10 ( 7a – c ), Me2GaS2C‐N(2‐Ad)‐NC5H10 ( 8 ) or Me2GaX2C‐N(2‐Ad)‐NC5H10 X = O ( 9 ); S ( 10 )] in moderate to good yields. Three different structural motifs were observed in the solid state: Five‐membered GaNCN2 heterocycles with exocyclic C=O bonds for compounds 7a – c , four‐membered GaSCN or GaSCS heterocycles for compounds 8 and 9 (chelating coordination of the Ga atoms by SCN and CS2 ligands) and an eight‐membered (GaOCO)2 heterocycle for the dimeric CO2 insertion product 10 . Treatment of 5 with PhCN or Ph2CO resulted in a completely different reaction and afforded a dimeric Ga imide 11a or an alcoholate 11b . These reactions may start by retro‐hydrogallation with the formation of H10C5N–N=C(C9H14) and Me2GaH and proceed by addition of the metal hydride to the polar multiple bonds of the nitrile or ketone. |
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Keywords: | Hydrazides Gallium Active Lewis pairs Hydrometallation Activation |
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