THE STRUCTURE OF OXO-BRIDGED TRINUCLEAR RUTHENIUM AND IRIDIUM HEXACARBOXYLATES

The reactions between ruthenium trichloride or iridium trichloride and carboxylic acids produce oxygen-centered triangular trinuclear complexes which are known as 'basic' carboxylates having the general formula [M(3)O(O(2)CR)(6)(H2O3](n+). Using ion-exchange chromatography, a variety of such complexes with different carboxylates and oxidation states were isolated and crystallized. The X-ray study of five compounds is reported. Compound 1,[RU(3)O(O2CCH3)(6)(H2O)(3)]BF4.2H(2)O is monoclinic, space group P2(1)/c with a=11.717(1), b=15.019(2), c=15.220(2) Angstrom, beta=92.27(3)degrees, V=2676(1) Angstrom(3) and Z=4. Compound 2, [Ru3O(O2CH)(6)(H2O)(6)]BF4.3H(2)O is orthorhombic, space group Pmn2(1) with a=11.362(1), b=6.676(1), c=14.447(2) Angstrom, V=1096(1) Angstrom(3) and Z=2. Compound 3, [Ru3O(O2CCH3)(6)(H2O)(3)](ClO4)(2).H2O is monoclinic, space group P2(1)/n with a=17.226(2), b=15.532(2), c=11.117(1) Angstrom, beta=91.68(2)degrees, V=2973(1) Angstrom(3) and Z=4. Compound 4(1) [Ir3O(O2CCH3)(6)(H2O)(3)]BF4.4H(2)O is monoclinic space group I2/a with a=22.305(6), b=14.098(3), c=20.119(5) Angstrom, beta=103.10(5)degrees, V=6162(5) Angstrom(3) and Z=8. Compound 5, [Ir3O(O2CCH3)(6)(H2O)(3)](ClO3)(1.667)(ClO4)(0.333) is rhombohedral, space group R $$($) over bar 3 with a=11.173(4), c=40.621(10) Angstrom, V=4392(4) Angstrom(3) and Z=6. The structural parameters, such as M-O (central) distances, for the M(III,III,III) and M(III,III,IV) systems are almost identical. This indicates that the removal of a d-electron from a non-bonding level of the M(3)O system has a very little or no effect at all on this system.