The crystal and molecular structure of potassium aquapentachloroiridate(III) and the H-1, C-13, N-15 NMR coordination shifts in iridium(III) chloride complexes with 2,2 '-bipyridine or 1,10-phenanthroline

摘要

The crystal and molecular structure of potassium aquapentachloroiridate(III) (K-2[Ir(H2O)Cl-5]) was reported. The [Ir(H2O)Cl-5](2-) anions are nearly octahedral, the axial Ir-Cl bond (2.322(2) angstrom) being shorter than the equatorial ones (2.346(2)-2.360(2) angstrom); the Ir-O bond length is 2.090(4) angstrom. Ir(III) chloride complexes with 2,2'-bipyridine (LL = bpy) or 1.10-phenanthroline (LL = phen), of the general formulae K[Ir(LL)CL4] and cis-[Ir(LL)(2)CL2]Cl, were studied by far-IR and H-1-C-13, H-1-N-15 HMBC/HMQC/HSQC-NMR. High-frequency H-1 NMR coordination shifts ( Delta(1H)(coord) = delta(1H)(complex) - delta(1H)(ligand); max. ca. + 1 ppm) were noted for [Ir(LL)Cl-4](-) anions, while for cis-[Ir(LL2)Cl-2](+) cations they had variable sign and magnitude (max. ca. +/- ppm); they were dependent on the proton position, being mostly expressed for the nitrogen-adjacent hydrogens (H(6) for bby, H(2) for phen). C-13 NMR signals were high-frequency shifted (by max. ca. 8 ppm), whereas all N-15 nuclei were shifted to the lower frequency (by ca. 105-120 ppm). The experimental H-1, C-13, N-15 NMR chemical shifts were reproduced by semi-empirical quantum-chemical calculations (B3LYP/LanL2DZ+6-31G**//B3LYP/LanL2DZ+6-31G*).