Investigation of the electron density of iridium(I) Vaska-type complexes using DFT calculations and structural results: Structure of trans-carbonyl-chloro-bis(tricyclohexylphosphine)-iridium(I)

[Ir(CO)Cl(PCy₃)₂] was obtained by the slow attack of 1,2-dichloromethane on (Bu₄N)[Ir₂(μ-Dcbp)(CO)₂(PCy₃)₂] (Dcbp = 3,5-dicarboxylatepyrazole). The Ir-CO, Ir-Cl and Ir-P bond distances are 1.778(10), 2.374(3) and 2.3486(8) Å, respectively. The Ir-P bond distances for a number of different Vaska complexes indicate the shortest bond distances for phoshines containing electron withdrawing groups. An excellent correlation between DFT (OLYP/ZORA/TZP) and experimental structures is obtained as reflected by the RMSD values (H excluded) of between 0.083 and 0.268 Å for the different complexes studied. The calculated Ir-P bond distances and ν(CO) stretching frequencies closely follow the trends obtained from the experimental results.