Comparative neutron and X-ray study of [PPN][HIr4(CO)9(μ-Ph2PCH2PPh2)]

Abstract

Abstract The structure of this tetranuclear iridium cluster featuring a terminal Ir–H bond has been investigated by neutron crystallography using the D19 diffractometer at the Institut Laue Langevin in Grenoble. The structure, which is stabilized by numerous C–H⋯O=C hydrogen bonds, has no π–π stacking. The neutron study described here resolves a difficulty encountered in previous X-ray work where it proved impossible to locate reliably the position of hydrogen in the presence of heavy iridium atoms. Neutron crystallography offers unique advantages for this type of problem and in this case has provided the first reliable value for a terminal Ir–H distance of 1.618(14) Å and an intramolecular H–H contact of 2.40(2) Å.