KINETIC STUDY OF ANATION REACTION OF MESO-TETRAKIS-(P-SULFONATOPHENYL)PORPHINATODIAQUARUTHENATE(III) WITH THIOCYANATE ION IN AQUEOUS SOLUTION

摘要

The reaction of NCS- (0.010-1.0 M) with Ru(TPPS)(H2O)(2)(5-) to form Ru(TPPS)(NCS)(2)(5-) has been studied at 35, 40, 45, 50 and 55 degrees C in mu = 1.00 M (NaClO4) and 0.010 M HClO4. The addition of the second NCS- is rapid compared to the first step. The reaction is interpreted to occur via a D mechanism with a pseudo-first-order rate constant that can best be described by the relationship k(obs) = a[NCS-]/(b+[NCS-]), where a is interpreted to be the rate constant for formation of an intermediate of reduced coordination number and b is a competition ratio {H2O/NCS-} for this intermediate. The values of a (k(1)) were (1.77 +/- 0.45) x 10(-8), (3.01 +/- 0.83) x 10(-4) (5.82 +/- 0.12) x 10(-4), (9.90 +/- 0.24) x 10(-4) and (1.73 +/- 0.73) x 10(-3) s(-1) at 35, 40, 45, 50 and 55 degrees C, respectively. At 35, 40, 45, 50 and 55 degrees C, the values of b (k(2)/k(3)) were (2.40 +/- 0.81), (1.78 +/- 0.69), (1.92 +/- 0.55), (1.44 +/- 0.52) and (1.09 +/- 0.64) M, respectively. The value of Delta H-not equal was (93.7 +/- 1.88) kJ mol(-1) and that of Delta S-not equal was (-13.3 +/- 5.95) J mol(-1) K-1. [References: 42]