Bt. Heaton et al., A SPECTROSCOPIC STUDY OF HALOCARBONYL COMPLEXES OF RHODIUM(I) AND RHODIUM(III), Journal of organometallic chemistry, 462(1-2), 1993, pp. 347-352
NMR studies (C-13 and Rh-103) show that mixing of equimolar amounts of
[RhX(2)(CO)(2)](-) and [RhY2(CO)(2)](-) (X not equal Y = Cl, Br, or I
) results in approximately statistical X/Y exchange to give cis-[RhXY(
CO)(2)](-). Products resulting from the addition of X(2) to [RhX(2)(CO
)(2)](-) (X = Cl, Pr, or I) have been characterized by NMR and IR spec
troscopic studies, and include the anions cis- and trans-[RhX(4)(CO)(2
)](-) which slowly lose CO to give the bis(halogen)-bridged dimer [Rh(
2)X(8)(CO)(2)](2-); the dimer progressively reacts with halide to give
the mono(halogen)-bridged dimer [Rh(2)X(9)(CO)(2)](3-), and this is f
ollowed by the formation of [RhX(5)(CO)](2-). The tendency for replace
ment of the halide trans to CO by methanol increases in the order X =
Cl < Br < I.