Characterization and Photochemistry of the Gallium and Indium Subhydrides Ga2H2 and In2H2 This work was supported by the Deutsche Forschungsgemeinschaft (Habilitation grant to H.-J. H.), the CNRS (L. M.), and the EPSRC (A. J. D.).

Herein we describe the cocondensation of Ga or In vapor with H2 in an excess of Ar at 10 ± 12 K, and the subsequent irradiation of the resulting matrix with light of different wavelengths. We show that the reaction of Ga2 or In2 with H2 directly or indirectly gives rise to three isomers of Ga2H2 and two isomers of In2H2, namely the bis( -hydrido) species Ga( -H)2Ga (1a) and In( -H)2In (1b), the trans-bent species HGaGaH (3a) and HInInH (3b), and GaGaH2 (2a) with two terminal Ga H bonds (Scheme 1). All these molecules have