Rhenium complex of a triply deprotonated chelated thiosemicarbazide and its conversion to a nitride complex via a hydrazide intermediate. Crystal structure of [ReCl2(NH)(NHNH2)(PPh3)2]

Abstract

Reaction of [Re(O)X₃(PPh₃)₂](X = Cl or Br) with thiosemicarbazides RNHCSNHNH₂(R = Me or Ph) in ethanol under reflux in the presence of aqueous HX and PPh₃ gave the rhenium(V) S,N-chelated thiosemicarbazide(3–) complexes [ReX₂(NNCSNHR)(PPh₃)₂]. On extended reflux for X = Cl the purple imide–hydrazide [ReCl₂(NH)(NHNH₂)(PPh₃)₂] was formed, and a crystal structure determination showed a pseudo-octahedral geometry with trans PPh₃ and nitrogen ligands and a significantly bent M–N–N system (145.5°). Further reflux gave the known nitride complex [Re(N)Cl₂(PPh₃)₂] in good yield.