A flexible framework obtained from oxidative additions upon the binuclear complex [Ir2(μ-pz)(μ-SBut)(CO)2{P(OMe) 3}2]: Preparation and X-ray structures of [Ir2(μ-pz)(μ-SBut)(μ-L)(CO) 2{P(OMe)3}2] and [Ir2(μ-pz)(μ-SBut)(μ-L)I2...

Resumen

Title full: A flexible framework obtained from oxidative additions upon the binuclear complex [Ir2(μ-pz)(μ-SBut)(CO)2{P(OMe) 3}2]: Preparation and X-ray structures of [Ir2(μ-pz)(μ-SBut)(μ-L)(CO) 2{P(OMe)3}2] and [Ir2(μ-pz)(μ-SBut)(μ-L)I2(CO) 2-{P(OMe)3}2] (Hpz = pyrazole, L = dimethyl acetylenedicarboxylate). The formation and properties of the heterobridged complexes [Ir2(μ-pz)(μ-SBut)(cod)2] (1) (cod = cyclo-octa-1,5-diene, pz = pyrazolate) and [Ir2(μ-pz)(μ-SBut)(CO)2{P(OMe) 3}2] (2) are reported. Compound (2) undergoes stepwise addition of molecular iodine to yield the complexes [Ir2(μ-pz)(μ-SBut)In;(CO) 2{P(OMe)3}2][n = 2 (3) and 4 (4)]. Interaction of complex (2) with dimethyl acetylenedicarboxylate affords the triply heterobridged complex [Ir2(μ-pz)(μ-SBut)(μ-MeO2CC=CCO 2Me)(CO)2{P(OMe)3}2] (5). Compound (5) undergoes a further oxidative addition with I2 to form [Ir2(μ-pz)(μ-SBut)(μ-MeO2CC=CCO 2Me)I2(CO)2{P(OMe)3}2] (6). Compound (6) can be also obtained using mercury(II) iodide as oxidant, and similarly, [Ir2(μ-pz)(μ-SBut)(μ-MeO2CC=CCO 2Me)Cl2(CO)2{P(OMe)3}2] (7) using mercury(II) chloride. The structures of (5) and (6) have been determined by X-ray diffraction methods. Crystals of (5) are monoclinic, space group P21/n, with a = 18.040(7), b = 15.986(6), c = 11.085(4) Å, β = 92.68(2)°, and Z = 4. Complex (6) is orthorhombic, space group P212121 with a = 13.522(5), b = 20.871 (8), c = 12.649(7) Å, with Z = 4. Both complexes are binuclear with the metal atoms held in proximity by a triple bridge: a pyrazolate anion, a ButS group and a dimethyl acetylenedicarboxylate ligand bonded as a cis-dimetallated olefin. The oxidative addition of I2 to (5) originates a remarkable change in the Ir-Ir distance from 2.614(2) to 3.626(2) Å, leaving practically unaltered the bridging framework.