13C NMR chemical shift tensors of metal carbonyls

Abstract
The principal components of the 13C NMR chemical shift tensors of metal carbonyls containing between one and six metal atoms were determined from their powder patterns. The tensors of terminally bound CO groups are highly anisotropic (380±60 ppm) and nearly axially symmetric. The tensors of bridging CO groups are much less anisotropic, due to significant asymmetry in the electron orbitals about the C–O internuclear axis. The tensors vary only slightly for different transition metals. There is no intramolecular rearrangement of the metal carbonyls in the solid state at frequencies greater than 10 kHz, except in Fe3(CO)12.