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)(mu-Br)](2) with 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene [Cl2C=C(H)-N= CPh2] (1a) yields the di-nuclear benzophenone azine-bridged compound [(OC)(3)Re(mu-Ph2C=N-N=CPh2)-(mu-Br)(2)Re(CO)(3)] (2a), albeit in low yield. Alternatively, compounds [(OC)(3)Re(mu-Ph2C=N-N=CPh2)(mu-X)(2)-Re(CO)(3)] (2a,b) (X=Br, Cl) are obtained in high yields by direct reaction of [Re(CO)(3)(THF)(mu-Br)](2) or [Re(CO)(5)Cl] with benzophenone azine. Nucleophilic attack of NaSPh on 1a affords the 2-azabutadiene derivative [(PhS)(Cl)C=C(H)-N=CPh2] (1b). which upon reaction with [Re(CO)(3)(THF)(mu-Br)](2) forms the S,N-chelate complex fac-[(OC)(3)ReBr((PhS)(Cl)C=C(H)-N=CPh2)] (3). The crystal structures of 1b, 2a and 3 have been determined and the luminescence properties of 2 and 3 have been investigated. (C) 2008 Elsevier B.V. All rights reserved.