The preparation and hydridic reduction of dicationic dicarbonyl complexes of osmium(II); the crystal and molecular structure of trans-bis[1,2-bis(diphenylphosphino)ethane-PP′]carbonylformylosmium(II) hexafluoroantimonate–dichloromethane (1/1)
Abstract
Reactions of cis- or trans-[OsCl2(dppm)2](dppm = Ph2PCH2PPh2) or trans-[OsCl2(dppe)2](dppe = Ph2PCH2CH2PPh2) with AgSbF6 under CO give cis-[Os(CO)2(dppm)2][SbF6]2 and trans-[Os(CO)2(dppe)2][SbF6]2 respectively, the latter via[OsCl2(dppe)2][SbF6]. Reductions of [Os(CO)2(P–P)2][SbF6]2(P–P = dppm or dppe) with K[BH(OPrI)3], Li[BHEt3], or Li[BDEt3] give [Os(CHO)(CO)(P–P)2][SbF6], [Os(CHO)(CO)(P–P)2][BEt4] and [Os(CDO)(CO)(P–P)2][SbF6] respectively without change of stereochemistry. Pure trans-[Os(CHO)(CO)(dppe)2][SbF6] is thermally very stable, although it decomposes rapidly to trans-[OsCl(CO)(dppe)2][SbF6] if contaminated with boron residues. Impure cis-[Os(CHO)(CO)(dppm)2]+ is much more stable than the purified complex, which decomposes to trans-[OsCl(CO)(dppm)2], cis-[OsH(CO)(dppm)2]+, and an unusual dimeric complex. The complexes have been fully characterised by analytical and spectroscopic means as well as by an X-ray structure analysis of trans-[Os(CHO)(CO)(dppe)2][SbF6]·CH3Cl2. Crystals of this complex are orthorhombic, space group Pn21a(![[triple bond, length half m-dash]](https://www.rsc.org/images/entities/char_e007.gif)
Pna21, no. 33), with a= 22.361(4), b= 20.209(2), c= 11.940(2)Å, and Z= 4. The structure was obtained from 2 301 observed intensities measured on an automatic diffractometer and refined to an R value of 0.059. The main features of interest are the long Os–C bond [2.155(28)Å] and the Os–C–O angle of 130.7(27)° for the formyl ligand.
Please wait while we load your content...
