Bromotricarbonylrhenium(I) complexes [ReBr(CO) 3 L] [L=Ph 2 PO(CH 2 ) 3 OPPh 2 (L 1 ), i Pr 2 PO(CH 2 ) 2 OP i Pr 2 (L 2 ), Cy 2 PO(CH 2 ) 2 OPCy 2 (L 3 )] were prepared by reaction of [ReBr(CO) 5 ] with L. X-ray crystallography showed them all to be mononuclear, with the CO ligands fac. Subsequent reaction with AgOTf gave fac-[Re(OTf)(CO) 3 L], as shown by IR and NMR spectra. By contrast, reaction of [ReH(CO) 5 ] with L 1–3 gave hydrido complexes, the nuclearity and stereochemistry of which depended on the identity of L, as was confirmed by X-ray crystallography of mer-[ReH(CO) 3 L 1 ], fac-[ReH(CO) 3 L 2 ] and [{ReH(CO) 4 } 2 (μ-L 3 )]. Protonation of the hydrido compounds at 183K with HBF 4 ·OMe 2 gave the corresponding non-classical cationic dihydrogen complexes (T 1(min) ∼15ms at 400MHz), which released H 2 at temperatures above critical temperatures (243–263K) that depended on the co-ligands.