Linear and bent oxo-bridged dinuclear rhenium(V) complexes with terminal and bridging pyrazole ligands

摘要

The [ReOX3(AsPh3)(OAsPh3)] (X = Cl or Br) complexes react with two equivalents of 3,5-dimetylopyrazole (3,5-Me(2)pzH) in acetone at room temperature to give [{Re(O)X-2(3,5-Me(2)pzH)(2)}(2)(mu-O)] (1 and 2). In the case of [ReOBr3(AsPh3)(OAsPh3)], a small quantity of the dinuclear rhenium complex [{Re(O)Br(3,5-Me(2)pzH)}(2)(mu-O)(mu-3,5-Me(2)pz)(2)] (3) has been isolated next to the main product 2. Treatment of [ReOX3(PPh3)(2)] compounds with two equivalents of 3,5-Me(2)pzH in acetone at room temperature leads to the isolation of symmetrically substituted dinuclear rhenium complexes [{Re(O)X(PPh3)}(2)(mu-O)(mu-3,5-Me(2)pz)(2)] (4 and 5). Refluxing of [ReO(OEt)X-2(PPh3)(2)] complexes with 3,5-Me(2)pzH in ethanol affords unsymmetrically substituted dinuclear rhenium [{Re (O)X(PPh3)}(mu-O)(mu-3,5-Me(2)pz)(2) {Re(O)X(3,5-Me(2)pzH)}] complexes (6 and 7). The complexes obtained in these reactions have been characterised by IR, UV-Vis, H-1 and P-31 NMR. The crystal and molecular structures have been determined for 1, 2, 3, 4, 6 and 7 complexes. (C) 2003 Elsevier B.V. All rights reserved. [References: 43]