Dirhenium(II) complexes containing monodentate and polydentate nitrile ligands

The complex Re2Cl4(mu-dppa)(2) (dppa=Ph2PNHPPh2) has been reacted with EtCN and PhCN to afford the complexes [Re2Cl3(mu-dppa)(2)(NCR)(2)]PF6 (R = Pt o r Ph), [Re2Cl3(mu-HN2C2Et2)(mu-dppa)(2)(NCEt)]Cl and [Re2Cl3(mu-HN2C2Et2)(m u-dppa)(2)(NCEt)]PF6)(2) which are derivatives of the [Re-2](4+), [Re-2](5) and [Re-2](6+) cores, respectively. This behaviour is similar to the reac tions of Re2Cl4(mu-dppm)(2) (dppm = Ph2PCH2PPh2) with monodentate nitriles. The reactions of Re2Cl4(mu-dppm)(2) with the polydentate nitrile ligands 1 ,4-dicyanobenzene (1,4-DCB), 1,4-dicyanobut-2-ene (1,4-DCBE) and tris(2-cya noethyl)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 [Re2Cl3(mu-dppm)(2)(1,4-DCB)(2)]PF 6, in which the Re=Re bond is retained (Re-Re distance 2.2637(12) Angstrom) and the 1,4-DCB ligands are monodentate. (C) 2000 Elsevier Science S.A. Al l rights reserved.