Crystal structure of the new palladium complexes tetra-kis-(1,3-di-methyl-imidazolium-2-yl-idene)palladium(II) hexa-deca-carbonyl-tetra-rhenium diethyl ether disolvate and octa-μ-carbonyl-di-carbonyl-tetra-kis-(tri-phenyl-phosphane)palladium-dirhenium (unknown solvate).

Abstract

The investigation of the coordination chemistry of heterometallic transition-metal complexes of palladium (Pd) and rhenium (Re) led to the isolation and crystallographic characterization of tetra-kis-(1,3-di-methyl-imidazolium-2-yl-idene)palladium(II) hexa-deca-carbonyl-tetra-rhenium diethyl ether disolvate, [Pd(C5H8N2)4][Re4(CO)16]·2C4H10O or [Pd(IMe)4][Re4(CO)16]·2C4H10O, (1), and octa-μ-carbonyl-di-carbonyl-tetra-kis-(tri-phenyl-phosphane)palladium-dirhenium, [Pd4Re2(C18H15P)4(CO)10] or Pd4Re2(PPh3)4(μ-CO)8(CO)2, (2), from the reaction of Pd(PPh3)4 with 1,3-di-methyl-imidazolium-2-carboxyl-ate and Re2(CO)10 in a toluene-aceto-nitrile mixture. In complex 1 the Re-Re bond lengths [2.9767 (3)-3.0133 (2) Å] are close to double the covalent Re radii (1.51 Å). The palladium-rhenium carbonyl cluster 2 has not been structurally characterized previously; the Pd-Re bond lengths [2.7582 (2)-2.7796 (2) Å] are about 0.1 Å shorter than the sum of the covalent Pd and Re radii (1.39+1.51 = 2.90 Å). One carbene ligand and a diethyl ether mol-ecule are disordered over two positions with occupancy ratios of 0.5:0.5 and 0.625 (15):0.375 (15) in 1. An unidentified solvent is present in compound 2. The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule(s). The SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] in PLATON was used to remove the contribution of the electron density in the solvent region from the intensity data and the solvent-free model was employed for the final refinement. The cavity with a volume of ca 311 Å3 contains approximately 98 electrons.