ELECTRONIC-STRUCTURE OF RHODIUM(II) DIMERS OF FORMULA [RH2X2(MU-O2CH)2(HN=CHCH=NH)2] (X=HALIDE)

The electronic structures of the dirhodium complexes [Rh2(mu-O2CH)4(H2 O)2] and [Rh2X2(mu-O2CH)2-(HN=CHCH=NH)2] (X = Cl, Br or I) have been c alculated by the Fenske-Hall method. The calculations gave the electro nic configurations sigma2pi4delta2delta2pi*4sigma* with sigma* as the lowest unoccupied molecular orbital for [Rh2(mu-O2CH)4(H2O)2] and hig hest occupied molecular orbital < 18a1, 16b1 (pi HN=CHCH=NH) < 17b1 ( sigma) for [Rh2X2(mu-O2CH)2(HN=CHCH=NH)2]. All Rh-Rh orbitals of the latter complexes have considerably higher ligand contributions than th ose of [Rh2(O2CH)4(H2O)2]. The strength of the Rh-Rh bond and the elec tronic spectra of the complexes are discussed.