Mono- and di-nuclear 2,3-diazabutadiene and 2-azabutadiene complexes of Rhenium(I): Syntheses, luminescence spectra and X-ray structures

Treatment of [Re(CO)3(THF)(μ-Br)]2 with 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene [Cl2Cdouble bond; length as m-dashC(H)–Ndouble bond; length as m-dashCPh2] (1a) yields the di-nuclear benzophenone azine-bridged compound [(OC)3Re(μ-Ph2Cdouble bond; length as m-dashN–Ndouble bond; length as m-dashCPh2)(μ-Br)2Re(CO)3] (2a), albeit in low yield. Alternatively, compounds [(OC)3Re(μ-Ph2Cdouble bond; length as m-dashN–Ndouble bond; length as m-dashCPh2)(μ-X)2Re(CO)3] (2a,b) (X = Br, Cl) are obtained in high yields by direct reaction of [Re(CO)3(THF)(μ-Br)]2 or [Re(CO)5Cl] with benzophenone azine. Nucleophilic attack of NaSPh on 1a affords the 2-azabutadiene derivative [(PhS)(Cl)Cdouble bond; length as m-dashC(H)–Ndouble bond; length as m-dashCPh2] (1b), which upon reaction with [Re(CO)3(THF)(μ-Br)]2 forms the S,N-chelate complex fac-[(OC)3ReBr{(PhS)(Cl)Cdouble bond; length as m-dashC(H)–Ndouble bond; length as m-dashCPh2}] (3). The crystal structures of 1b, 2a and 3 have been determined and the luminescence properties of 2 and 3 have been investigated.