Solid-state metal carbonyls. Part 5.—Tetrairidium dodecacarbonyl

Abstract

Infrared data have been collected for Ir₄(CO)₁₂ from 20 to 2500 cm^–1 at liquid-nitrogen temperature, and supplemented by new ambient-temperature Raman data. A coupling scheme is used to account for the construction of the ν(CO) region of the spectrum, and the effect of the three independently occupied sites in the unit cell is clearly identified.

In the ν(Ir—C), δ(IrCO) and low-frequency regions, the main features of the spectra can be accounted for on the basis of the molecular symmetry. Our data support an earlier suggestion that the E Ir₄ cluster mode is at 135 cm^–1. Lattice modes were found down to 24 cm^–1(i.r.).