ELECTROCHEMICAL OXIDATION OF DIAQUARUTHENIUM(II) COMPLEXES OF QUATERPYRIDINES AND CRYSTAL-STRUCTURE OF [RUL1(PPH3)2][CLO4]2 (L1 = '-TETRAMETHYL-2,2',6',2'',6'',2'''-QUATERPYRIDINE)
Cw. Chan et al., ELECTROCHEMICAL OXIDATION OF DIAQUARUTHENIUM(II) COMPLEXES OF QUATERPYRIDINES AND CRYSTAL-STRUCTURE OF [RUL1(PPH3)2][CLO4]2 (L1 = '-TETRAMETHYL-2,2',6',2'',6'',2'''-QUATERPYRIDINE), Journal of the Chemical Society. Dalton transactions, (6), 1994, pp. 895-899
The perchlorate salts of (RuL2(OH2)2]2+ 1 and [RuL1(OH2)2]2+ 2 (L2 = 2
,2':6',2'':6'',2'''-quaterpyridine, L1 = '-tetramethyl-2,2':6',2'':6''
,2'''-quaterpyridine) have been isolated. In acidic solutions both 1 a
nd 2 exhibit reversible Ru(VI)-Ru(IV) and Ru(III)-Ru(II) couples, thou
gh the Ru(IV)-Ru(III) couples are only quasireversible. The effect of
pH on the E 1/2 of these couples has been investigated. At pH 1, the E
-degrees values of the ([RuLO2]2+)-O-2-[RuL2(O)(OH2)]2+ and [RuLO-1(2)
]2+-[RuL1(O)(OH2)]2+ couples are 1.12 and 1.05 V vs. saturated calomel
electrode respectively. The crystal structure of [RuL1(PPh3)2][ClO4]2
. MeCN.H2O has been determined: monoclinic space group P2(1)/n, a = 13
.210(4), b = 29.711(7) c =14.878(3) angstrom, beta = 98.89(2)-degrees,
Z = 4. In this complex the quaterpyridine ligand adopts a non-planar
conformation with a dihedral angle of 28.3-degrees between the two cen
tral pyridyl rings. The two triphenyl-phosphine ligands are in a trans
configuration [P(l)-Ru-P(2) 177.6-degrees]. The complex (RuL2(OH2)2]2
+ is an active catalyst for the electrochemical oxidation of propan-2-
ol.