Ruthenium(II) complexes of benzylphosphines

Article abstract of DOI:10.1021/ic00134a021

Reaction of the benzylphenylphosphines Bzl_nPPh_3-n (L) with Ru(CO)₂Cl₂ produces the kinetically stable trans-L₂Ru(CO)₂Cl₂ (1), which thermally isomerize to the thermodynamically stable cis-L₂Ru(CO)₂Cl₂ (2). The kinetics, activation thermodynamics, and mechanisms of these processes were determined by ³¹P NMR spectroscopy. The isomerization is a dissociative process (ΔS^≠ and ΔH^≠ are both positive) whose rate increases with an increase in the steric bulk of the phosphine and is retarded by excess carbon monoxide. A series of six complexes have been characterized by elemental analyses and infrared and ¹H, ¹³C{¹H}, and ³¹P NMR spectroscopies. The crystal structures of trans-(Bzl₃P)₂Ru(CO)₂Cl₂ and cis-(BzlPPh₂)₂Ru(CO)₂Cl₂ have been determined from three-dimensional X-ray diffraction techniques. The structural data form a basis for discussion of the relative thermodynamic and kinetic stabilities of the isomers formed.