Crystal and molecular structure of bis-(π-2-methylallyl)bis(trimethyl phosphite)ruthenium. An example of asymmetric π-bonding between methylallyl ligands and ruthenium

Abstract

The crystal structure and molecular stereochemistry of the title compound have been determined from three-dimensional X-ray diffraction counter data by Patterson and Fourier methods. Crystals are monoclinic, a= 15·12, b= 17·86, c= 8·10 Å, β= 113·4°, space group P2₁/a, Z= 4. The structure has been refined by least-squares methods to R 0·051 for 677 independent reflections. The ruthenium atom is octahedrally co-ordinated and has the trimethyl phosphite ligands mutually cis; the methylallyl groups each occupy two adjacent sites. The bonding of each methylallyl group to the ruthenium atom is asymmetric: mean Ru–C(trans to P) 2·38(2); mean Ru–C(trans to C) 2·18(2)Å. The methylallyl groups are non-planar, the methyl group being bent out of the plane of the allyl moiety by some 12° away from the metal. The allyl plane is almost exactly perpendicular to the plane defined by the two outer carbon atoms and the ruthenium atom.