A cationic zinc hydride cluster stabilized by an N-heterocyclic carbene: synthesis, reactivity, and hydrosilylation catalysis.

The trinuclear cationic zinc hydride cluster (IMes)3Zn3H4(THF)2 (1) was obtained either by protonation of the neutral zinc dihydride [(IMes)ZnH2]2 with a Brønsted acid or by addition of the putative zinc dication (IMes)Zn(THF). A triply bridged thiophenolato complex 2 was formed upon oxidation of 1 with PhS-SPh. Protonolysis of 1 by methanol or water gave the corresponding trinuclear dicationic derivatives. At ambient temperature, 1 catalyzed the hydrosilylation of aldehydes, ketones, and nitriles. Carbon dioxide was also hydrosilylated under forcing conditions when using (EtO)3SiH, giving silylformate as the main product.