Abstract
This paper describes a work aimed at determining the molecular structure of a rhodium(I) complex along an experimental track in which a conventional X-ray single crystal structural analysis was accidentally preceded by a power X-ray diffractometric investigation. The complex [Rh(dppf) 2]BPh 4 (dppf = 1,1′-bis(diphenylphosphino)ferrocene) was obtained from dichloroethane in two crysttalline forms, hereafter referred to as α and β, which are different in colour and in the content of lattice-entrapped solvent. Conventional and synchrotron powder wide angle X-ray diffractometry (WAXS), FT-IR, 31P and 1H NMR spectroscopy demonstrate that α and β are dimorphic forms of the same molecular entity. The observed WAXS spectrum of the α form was computationally fitted ( R = 11.3%) with that calculated for [Rh(dppf) 2]BPh 4, upon assuming that the molecular geometry of the title complex was identical to that of the already determined iridium analogue, i.e. square-planar with a pronounced tetrahedral distortion. X-ray single crystal analysis confirmed this conclusion. FT-IR, DSC and TG analyses have also been employed for a solid state characterization of the two species.
Published Version
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