In this review article, we discuss advances in the chemistry of metal carbonyl clusters (MCCs) spanning the last three decades, with an emphasis on the more recent reports and those involving groups 8–10 elements.

The reaction of Na[Co(CO)₄] with M(IPr)Cl (M = Cu, Ag, and Au; IPr = C₃N₂H₂(C₆H₃ⁱPr₂)₂) affords the neutral heterometallic complexes [Co(CO)₄{M(IPr)}] (M = Cu, 1; Ag, 2; and Au, 3). Formation of 2 is accompanied by traces of [Ag(IPr)₂][Ag{Co(CO)₄}₂] (4). The reaction of Na[Co(CO)₄] with M(IMes)Cl (IMes = C₃N₂H₂(C₆H₂Me₃)₂) results in mixtures of [Co(CO)₄{M(IMes)}] (M = Cu, 5; Ag, 6; and Au, 7) and [M(IMes)₂][M{Co(CO)₄}₂] (M = Cu, 8; Ag, 9; and Au, 10). In the cases of Cu and Ag, ionic complexes 8 and 9 are the major products, whereas neutral species 7 is the major product for Au. All species 1–10 have been spectroscopically characterized by IR and ¹H and ¹³C{¹H} NMR spectroscopy. Moreover, the molecular structures of 2, 3, and 8 have been determined by single-crystal X-ray diffraction (SC-XRD). Bimetallic Co–M–NHC complexes 1–3 and 7–9 have been tested as catalysts for the dehydrogenation of ammonia–borane (AB) in THF as solvent, and their performances compared to [Fe(CO)₄{M(NHC)}₂], M(NHC)Cl, and Na[Co(CO)₄]. DFT computations have been performed to provide information on the structure, IR spectroscopy, and the thermodynamics of Co–M carbonyl clusters.

The [H₃Ru₄(CO)₁₂]⁻polyhydride carbonyl cluster has been obtained using a one-pot synthesis by reductive carbonylation of RuCl₃·3H₂O at CO-atmospheric pressure.

The isolation and structural characterization of the [HRu₄(CO)₁₂]³⁻carbonyl anion are reported for the first time, more than 40 years after its first spectroscopic evidence.