mer-[MCl3(Me2pzH)3] (M = Rh, Ir; Me2pzH = 3,5-dimethylpyrazole): X-ray structures, spectroscopic properties, and density functional theory (DFT) calculations

The complexes mer-[MCl3(Me2pzH)3] · CH3OH (M = Rh, Ir; Me2pzH = 3,5-dimethylpyrazole) have been characterized by nuclear magnetic resonance, infrared, and ultraviolet–visible absorption spectroscopies, and by single crystal X-ray diffraction. Density functional theory (DFT) calculations were carried out for mer-[IrCl3(Me2pzH)3] with the point group constrained as Cs and with the point group unconstrained (C1). Both DFT-calculated molecular structures compare very well with the actual X-ray structure, and the calculated infrared spectrum, with Cs symmetry, closely resembles the actual infrared spectrum of mer-[IrCl3(Me2pzH)3] · CH3OH. The observed H → L electronic transition occurs at 471 nm in mer-[IrCl3(Me2pzH)3]. (The H orbital is the highest occupied molecular orbital, and the L orbital is the lowest unoccupied molecular orbital.) The H → L transition is calculated to occur at 470 nm with Cs symmetry, and at 485 nm with C1 symmetry.