The synthesis of ReH 7 (AsPh 3 ) 2 is reported. Surprisingly, this complex appears to be a classical heptahydride and is remarkably resistant to substitution by nitrogen and phosphorus donor ligands. The reactivity of this polyhydride towards silanes and stannanes was also studied. The new complexes, ReH 6 (SiPh 3 )(AsPh 3 ) 2 and ReH 6 (SnPh 3 )(AsPh 3 ) 2 , are formed with Ph 3 EH (E = Si, Sn) but ReH 7 (AsPh 3 ) 2 does not react with chelating silanes. These products appear to be more stable than their phosphine-supported analogues.