THERMAL AND PHOTOCHEMICAL REACTIVITY OF TETRAAMINERUTHENIUM COMPLEXESCONTAINING 1,3,5-TRIAZA-7-PHOSPHAADAMANTANE AS A LIGAND

The k(1) and k(-1) values for the thermal reaction: trans-[Ru(NH3)(4)( TPA) (TPAH)](3+) + H3O+ (kappa 1)reversible arrow(k-1) trans-[Ru(NH3)( 4)(TPA)(H2O)](3+) + TPAH(+), where TPA = 1,3,5-triaza-7-phosphaadamant ane, are 1.5 +/- 0.1 M-1 s(-1) and 9.1 +/- 0.5 x 10(-3) s(-1), respect ively, (at 25.0 +/- 0.1 degrees C, mu = 0.10 mol L-1, pH = 2.6, CF3COO H). The E-RuIII/RuII(0') in the trans-[Ru(NH3)(4)(TPAH)(H2O)](3+) spec ies is 0.60 V (vs SCE) in aqueous solution at room temperature (mu = 0 .10 mol L-1/CF3COONa, pH = 2.6/CF3COOH). The electronic spectral chara cteristics of trans-[Ru(NH3)(4)(TPAH)(H2O)](3+) are lambda = 254 nm, e psilon = 1.48 x 10(4) M-1 cm(-1) ((1)A(1) --> E-1((1))) and lambda = 3 20 nm, epsilon = 1.40 x 10(3) M-1 cm(-1) ((1)A(1) --> (1)A(2)). The am monia ligand is photolabilized when trans-[Ru(NH3)(4)(TPAH)H2O](3+) Or trans-[Ru(NH3)(4)(TPA)H2O](2+) are irradiated, phi(NH3) = 0.32 +/- 0. 04 mol/einstein (CH+ = 1.0 x 10(-3) -1.0 x 10(-6) mol L-1). The substi tution reaction of pyrazine In trans-[Ru(NH3)(4) (TPAH)(H2O)](3+) proc eeds at pH = 1.6, with k(1) = 0.17 +/- 0.02 mol(-1) L s(-1) and k(-1) = 0.033 +/- 0.002 s(-1) and in trans-[Ru(NH3)(4)(TPA)(H2O)](2+) at pH = 6.2, with k(1) = 0.93 +/- 0.02 mol(-1) L s(-1) and k(-1) = 0.043 +/- 0.002 s(-1) (at 25.0 +/- 0.1 degrees C, mu = 0.10 mol L-1, CF3 COONa/ CF3COOH). An increase in the transition-metal catalyst solubility in w ater can be achieved by replacing the ETPB and P(OPh)(3) ligands by TP AH(+) and the P(OCH2CH2Cl)(3), PPh3, dppe, H(2)Pcy and P(OMe)(3) ligan ds by TPA without any noticeable change in reactivity since their tran s effects are about the same. In the same way, if the trans influence is the important factor, the P(OCH2CH2Cl)(3), P(OPh)(3), and dppe liga nds have about the same trans influence as TPAH(+) and the PPh3 P(OEt) (3), P(OBut)(3), P(OPrl)(3), P(OBun)(3) and P(OH)(3) ligands about the same trans influence as TPA.