Inorg. Chem. 1984, 23, 2413-2482
2473
Contribution from the Department of Chemistry, Faculty of Military Studies, Royal Military College, University of New South Wales, Duntroon, Canberra, ACT 2600, Australia, and Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia
Base Hydrolysis of Anionopentaamminecobalt(111) Complexes: The Role of Ion Association and the Question of a Common Coordinatively Unsaturated Intermediate W. G. JACKSON,*+ C. N. HOOKEY? M. L. RANDALL: P. COMBA,* and A. M. SARGESON*t
Received September 13, 1983 This paper examines critically the relationship between the rate law and product distribution for the base hydrolysis of [(NH,),CoX]"+ in the presence of competing anions Ym. It is concluded that there is no relationship, supporting our previous contention that the product-determining step is not rate determining and implicating a reactive intermediate, five-coordinate [ (NH3)4(NHz)Co]2+.Rate law studies employing the strongly ion-pairing S042-,CO:-, S2032-, and P043- anions reveal a correlation with their ion-pairing capacities. Ion-pair constants have been determined independently for some model [(NH3),CoX]"+ (n = 2, 3) complexes with C03z-, SO:-, and PO:-. Parallel product distribution studies show no obvious correlation with ion pairing. For example, the strongly ion-pairing PO4> and CO,' ions are shown to be very poor competitors, S042-is a weak competitor, and S2032-is a reasonable competitor. Furthermore, the poorly ion-pairing 1- anions N
