Dirhenium(II) complexes containing monodentate and polydentate nitrile ligands

Abstract

The complex Re 2Cl 4(μ-dppa) 2 (dppa=Ph 2PNHPPh 2) has been reacted with EtCN and PhCN to afford the complexes [Re 2Cl 3(μ-dppa) 2(NCR) 2]PF 6 (R=Et or Ph), [Re 2Cl 3(μ-HN 2C 2Et 2)(μ-dppa) 2(NCEt)]Cl and [Re 2Cl 3(μ-HN 2C 2Et 2)(μ-dppa) 2(NCEt)](PF 6) 2 which are derivatives of the [Re 2] 4+, [Re 2] 5+ and [Re 2] 6+ cores, respectively. This behaviour is similar to the reactions of Re 2Cl 4(μ-dppm) 2 (dppm=Ph 2PCH 2PPh 2) with monodentate nitriles. The reactions of Re 2Cl 4(μ-dppm) 2 with the polydentate nitrile ligands 1,4-dicyanobenzene (1,4-DCB), 1,4-dicyanobut-2-ene (1,4-DCBE) and tris(2-cyanoethyl)phosphine (CEP) also give complexes of this same type in which the nitrile ligand utilizes only one of its CN groups. This is confirmed by an X-ray crystal structure determination of [Re 2Cl 3(μ-dppm) 2(1,4-DCB) 2]PF 6, in which the ReRe bond is retained (Re–Re distance 2.2637(12) Å) and the 1,4-DCB ligands are monodentate.