Polukeev Alexey V, Marcos Rocío, Ahlquist Mårten S G, Wendt Ola F
Centre for Analysis and Synthesis, Department of Chemistry, Lund University, PO Box 124, 22100, Lund, Sweden.
Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91, Stockholm, Sweden.
Chemistry. 2016 Mar 14;22(12):4078-86. doi: 10.1002/chem.201505133. Epub 2016 Feb 16.
The hydride iridium pincer complex [(PCyP)IrH2] (PCyP=cis-1,3-bis[(di-tert-butylphosphino)methyl]cyclohexane, 1) reveals remarkably solvent-dependent hydride chemical shifts, isotope chemical shifts, JHD and T1(min), with rHH increasing upon moving to more polar medium. The only known example of such behaviour (complex [(POCOP)IrH2], POCOP=2,6-(tBu2PO)2C6H3) was explained by the coordination of a polar solvent molecule to the iridium (J. Am. Chem. Soc. 2006, 128, 17114). Based on the existence of an agostic bond between α-C-H and iridium in 1 in all solvents, we argue that the coordination of solvent can be rejected. DFT calculations revealed that the structures of 1 and [(POCOP)IrH2] depend on the dielectric permittivity of the medium and these compounds adopt trigonal-bipyramidal geometries in non-polar media and square-pyramidal geometries in polar media.
氢化物铱钳形配合物[(PCyP)IrH₂]（PCyP = 顺式-1,3-双[(二叔丁基膦基)甲基]环己烷，1）显示出显著的溶剂依赖性氢化物化学位移、同位素化学位移、JHD和T₁(min)，随着向极性更强的介质转变，rHH增大。这种行为的唯一已知例子（配合物[(POCOP)IrH₂]，POCOP = 2,6-(tBu₂PO)₂C₆H₃）是由极性溶剂分子与铱的配位作用来解释的（《美国化学会志》2006年，128卷，17114页）。基于在所有溶剂中1中α-C-H与铱之间存在的agostic键，我们认为溶剂的配位作用可以被排除。密度泛函理论计算表明，1和[(POCOP)IrH₂]的结构取决于介质的介电常数，并且这些化合物在非极性介质中采用三角双锥几何构型，在极性介质中采用四方锥几何构型。
