UNLIGATED DIRHODIUM TETRA(TRIFLUOROACETATE) - PREPARATION, CRYSTAL-STRUCTURE AND ELECTRONIC-STRUCTURE

The title compound, Rh-2(O2CCF3)(4), without any exogenous axial ligands, has been obtained in crystalline form by sublimation. Its crystal structure has been determined: space group P ($) over bar 1 with a = 5.2499(5), b = 8.491 (2), c = 9.172(2) Angstrom, alpha = 88.80(2), beta = 88.53(1), gamma = 76.43(1)degrees, V = 397.3(1) Angstrom 3, Z = 1. The molecules are linked by axially ligating each other to form infinite chains. The Rh-Rh distance is 2.3813(8) Angstrom. The volatility of Rh-2(O2CCF3)(4) should allow spectroscopic study of the isolated molecules and therefore the electronic structure has been treated by the SCF-X alpha-SW method. The level ordering and composition show significant differences from those of Rh,(O,CH)4, although in both molecules there is a strong Rh-Rh sigma bond. Ionization potentials have been estimated by the transition state method.