Rh–Sb Nanoclusters: Synthesis, Structure, and Electrochemical Studies of the Atomically Precise [Rh₂₀Sb₃(CO)₃₆]^3– and [Rh₂₁Sb₂(CO)₃₈]^5– Carbonyl Compounds

Abstract

The reactivity of [Rh 7 (CO) 16 ] 3– with SbCl 3 has been deeply investigated with the aim of finding a new approach to prepare atomically precise metalloid clusters. In particular, by varying the stoichiometric ratios, the reaction atmosphere (carbon monoxide or nitrogen), the solvent, and by working at room temperature and low pressure, we were able to prepare two large carbonyl clusters of nanometer size, namely, [Rh 20 Sb 3 (CO) 36 ] 3– and [Rh 21 Sb 2 (CO) 38 ] 5– . A third large species composed of 28 metal atoms was isolated, but its exact formulation in terms of metal stoichiometry could not be incontrovertibly confirmed. We also adopted an alternative approach to synthesize nanoclusters, by decomposing the already known [Rh 12 Sb(CO) 27 ] 3– species with PPh 3 , willing to generate unsaturated fragments that could condense to larger species. This strategy resulted in the formation of the lower-nuclearity [Rh 10 Sb(CO) 21 PPh 3 ] 3– heteroleptic cluster instead. All three new compounds were characterized by IR spectroscopy, and their molecular structures were fully established by single-crystal X-ray diffraction studies. These showed a distinct propensity for such clusters to adopt an icosahedral-based geometry. Their characterization was completed by ESI-MS and NMR studies. The electronic properties of the high-yield [Rh 21 Sb 2 (CO) 38 ] 5– cluster were studied through cyclic voltammetry and in situ infrared spectroelectrochemistry, and the obtained results indicate a multivalent nature.

Structural Diversity in Molecular Nickel Phosphide Carbonyl Nanoclusters

“…This represents the first case of a phosphide atom enclosed within an icosahedral cage in a transition metal cluster. Indeed, P atoms are usually found in smaller cages with coordination numbers comprised in the range 5–10. − ,,,− Icosahedra are often found with larger heteroatoms, such as Sn, Sb, Bi, and Ge. , …”

Recent advances in atomic cluster synthesis: a perspective from chemical elements

“…112) and three pentagonal-antiprismatic [Sb 3 Rh 20 (CO) 36 ] 3− (ref. 113) complexes. It is worth mentioning that as a technique for clustering certain metals or mixing different metal elements in a cluster, the method using multiple ligands with different functional groups has been investigated, such as Fe 8 ( N [ o -H 2 NC 6 H 4 NH(CH 2 ) 2 ] 3 ) 2 (PMe 2 Ph) 2 with tetraamine and phosphine ligands, 114 Ga 6 (C 6 Me 3 H 2 ) 4 (C 3 N 2 Me 2 Pr 2 ) 2 with mesityl and tetraalkylimidazol-2-ylidene ligands, 115 [Mg 16 (C 5 Me 5 ) 8 (NEt 3 ) 2 Br 4 ] 2− with cyclopentadienyl and amine ligands, 116 Cu 10 Zn 2 (C 6 Me 3 H 2 ) 6 (C 5 Me 5 ) 2 with mesityl and cyclopentadienyl ligands, 117 Ir 4 Au 2 (CO) 11 (PPh 3 ) 2 , 118 Pt 13 Au 4 (CO) 10 (PPh 3 ) 8 , 119 and Pd 145 (CO) x (PEt 3 ) 30 ( x ≈ 60) 120 with carbonyl and phosphine ligands (Fig.…”

“…58) and Co 6 Te 8 (PR 3 ) 6 ,72 where the transition metal and chalcogen atoms occupy reversed positions in the same symmetric structure. Moreover, [Sb 3 Rh 20 (CO) 36 ] 3− reported as a ligand-protected cluster with a few free post-transition metal atoms113 and [Sn 9 Ni 2 (CO)] 3− reported as a Zintl cluster with a few…”