The thermodn. and kinetic parameters of configuration transformation of compounds (Ph2PR)2Co(C6Cl5)2 (R = Et, Pr) in benzene solution have been determine This new type of equilibrium of configuration transformation involving intramol. addition coordination was discussed. Initial and equilibrium octahedral configurations have different addition coordination; the coordination involving Ph ortho-hydrogen is more stable than that involving terminal hydrogen of the R group. The stability of tetrahedral configuration is lower; the configurational transformation is primarily dependent on the size of R groups.

Key words: BENZENE, EQUILIBRIUM CONSTANT, THERMODYNAMIC FUNCTION, COBALT COMPLEX, DIPHENYLPHOSPHINE, CHLOROBENZENE P, CONFIGURATION, ORGANO TRANSITION METAL COMPLEX