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Treatment of the carbonyl dimer Rh2Cl2(CO)4 with 2 equivalents of LiOAr-2,6Ph2 (OAr-2,6Ph2 = 2,6-diphenylphenoxide) produces the aryloxide bridged dimer [(CO)2Rh(μ-OAr-2,6Ph2)2Rh(CO)2] (1) in excellent yield. Compound 1 shows two, equal intensity carbonyl stretching frequencies at 2090 and 2006 cm−1 in the IR spectrum (Nujol mull) consistent with a solid state structure consisting of two edge shared square planes. A single crystal X-ray diffraction analysis of 1 confirmed this formulation showing no evidence for Π-bonding by the side chain aryl groups to the 16-electron metal centre. Treatment of the dimer Ir2Cl2(COD)2 (COD = 1,5-cyclooctadiene) with LiOAr-2,6Ph2 yielded a mixture of products. Eventually sparingly soluble crystals of a salt [(COD)Ir(η5-HOAr-2,6Ph2)]+[(COD)Ir(OAr-2,6Ph2)2]− (2) were obtained in very minor yield. The presence of a 2,6-diphenylphenol ligand η5-bound through the central phenoxy ring to the iridium metal centre was confirmed by a single crystal X-ray diffraction analysis of 2. The distances IrC to the COD ligand in the cation in 2, 2.10(2)–2.16(2) A, are slightly shorter than the distances of 2.25(2)–2.35(2) A to the five carbon atoms of the central phenoxy ring. The ipso carbon attached to the hydroxyl group is non-bound. The anion in 2 contains two terminal aryloxide ligands bound approximately trans to the two iridium-olefinic bonds of the COD group yielding a structure best described as square planar. Crystal data at 20°C for Rh2O6C40H26 (1): a = 10.750(2), b = 28.307(5), c = 11.311(2) A, β = 96.21(1)°, Z = 4, dcalc = 1.569 g cm−3 in space group P21/n; for Ir2Cl6O3C72H58 (2) 2CHCl3: a = 13.428(2), b = 22.838(3), c = 20.937(2) A, β = 92.775(9)°, Z = 4, dcalc = 1.624 g cm−3 in space group P21/n. |
