The trinuclear cationic zinc hydride cluster [(IMes)3Zn3H4 (THF)](BPh4)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)] 2+. 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. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.