Preparation of bis(aryldiazene) and new aryldiazenido complexes of rhenium

Mixed-ligand hydride ReH2(NO)L(PPh3)(2) Complexes [L = P(OEt)(3) or PPh(OEt)(2)] were prepared by allowing the ReH2(NO)(PPh3)(3) species to react with an excess of phosphite. Treatment of ReH2(NO)L(PPh3)(2) hydrides with an equimolar amount of aryldiazonium cations ArN2+ gives the mono-aryldiazene [ReH(ArN=NH)(NO)L(PPh3)(2)]BPh4 complexes (Ar = C6H5, 4CH(3)C(6)H(4)), while treatment with an excess of ArN2+ yields bis(aryldiazene) [Re(ArN=NH)(2)(NO)L(PPh3)(2)](BPh4)(2) derivatives. Binuclear [{ReH(NO)L(PPh3)(2)}(2)( t-HN=NAr-ArN=NH)](BPh4)(2) and [{Re(4-CH(3)c(6)H(4)N=NH)(NO)L(PPh3)(2)}(2)(-HN=NArArN=NH)](BPh4)(4) complexes (Ar-Ar = 4,4'-C6H4-C6H4, 4,4'-C6H4-CH2-C6H4) were also prepared. The reaction of the triphenylphosphine ReH2(NO)(PPh3)(3) complex with aryldiazonium cations was studied and led exclusively to mono-aryldiazene [ReH(ArN=NH)(NO)(PPh3)(3)]BPh4 and [{ReH(NO)(PPh3)(3)}(2)(w-HN=NAr-ArN=NH)](BPh4)(2) derivatives. The complexes were characterised spectroscopically (IR, NMR) using the N-15-labelled derivatives. The aryldiazenido [ReH(C6H5N2){PPh(OEt)(2)}(4)]BPh4 complex was prepared by allowing trihydride ReH3[PPh(OEt)(2)](4) to react with phenyldiazonium tetrafluoroborate. A reaction path involving the aryldiazene [ReH2(C6H5N=NH){PPh(OEt)(2)}(4)](+) intermediate was also proposed. (C) 2003 Elsevier B.V. All rights reserved.