Indium trihydride

Indium trihydride is an inorganic compound with the chemical formula (InH3). It has been observed in matrix isolation and laser ablation experiments. Gas phase stability has been predicted. The infrared spectrum was obtained in the gas phase by laser ablation of indium in presence of hydrogen gas InH3 is of no practical importance.

Chemical properties
Solid InH3 is a three-dimensional network polymeric structure, where In atoms are connected by In-H-In bridging bonds, is suggested to account for the growth of broad infrared bands when samples of InH3 and InD3 produced on a solid hydrogen matrix are warmed. Such a structure is known for solid AlH3. When heated above $-90 °C$, indium trihydride decomposes to produce indium–hydrogen alloy and elemental hydrogen. As of 2013, the only known method of synthesising indium trihydride is the autopolymerisation of indane below $-90 °C$.

Other indium hydrides
Several compounds with In-H bonds have been reported. Examples of complexes with two hydride ligands replaced by other ligands are (K+)3[K((CH3)2SiO)7+][InH(CH2C(CH3)3)3–]4 and HIn(\sC6H4\sortho\-CH2N(CH3)2)2.

Although InH3 is labile, adducts are known with the stoichiometry InH3L_{n} (n = 1 or 2). 1:1 amine adducts are made by the reaction of Li+[InH4]− (lithium tetrahydridoindate(III)) with a trialkylammonium salt. The trimethylamine complex is only stable below −30 °C or in dilute solution. The 1:1 and 1:2 complexes with tricyclohexylphosphine (PCy3) have been characterised crystallographically. The average In-H bond length is 168 pm. Indium hydride is also known to form adducts with NHCs.