KINETIC HYDRICITY OF TRANSITION-METAL HYDRIDES TOWARD TRITYL CATION

The kinetics of hydride transfer from a series of metal hydrides (MH) to Ph(3)C(+)BF(4)(-) (producing Ph(3)-CH and M- - -FBF3) have bean stu died by stopped-flow methods in CH2Cl2 solution. Second-order rate con stants at 25 degrees C span 5 orders of magnitude in kinetic hydricity , ranging from k = 5.0 x 10(1) M(-1) s(-1) for HMn-(CO)(5) to k = 4.6 x 10(6) M(-1) s(-1) for trans-HMo(CO)(2)-(PMe(3))Cp.