What question did this study set out to answer?

To synthesize and characterize new diphosphine-substituted rhodium carbonyl clusters.

January 6, 2026Molecules0 citationsOpen Access

Diphosphine-Substituted Rhodium Carbonyl Clusters: Synthesis and Structural and Spectroscopic Characterization of the Heteroleptic Rh4 (CO) 8+2n (L) 2−n (n = 0, 1) and Rh4 (CO) 10L2 Monomeric and Dimeric Species

GSGiorgia ScorzoniUniversity of Bologna GBGuido BussoliUniversity of Bologna CCCristiana CesariUniversity of Bologna

Key Points

To synthesize and characterize new diphosphine-substituted rhodium carbonyl clusters.
Synthesis of tetranuclear rhodium carbonyl clusters using bidentate diphosphines under homogeneous conditions at room temperature.
Characterization performed using infrared spectroscopy and single-crystal X-ray diffraction.
Dynamic behavior analyzed using variable-temperature 31P{1H} NMR spectroscopy.
Five new heteroleptic rhodium carbonyl species were isolated and characterized.
The Rh4 core was preserved across all synthesized compounds.
Cluster stability and dynamic interactions of phosphorus atoms were detailed.

Abstract

Tetranuclear rhodium carbonyl clusters are vital catalytic precursors; yet derivatives featuring bidentate phosphines are less common, due to the propensity for cluster fragmentation during synthesis. This study reports the successful isolation of five new heteroleptic species by reacting Rh4 (CO) 12 with various bidentate diphosphines under homogeneous conditions and at room temperature, namely the mono-substituted Rh4 (CO) 10 (dppe) (1) and Rh4 (CO) 10 (dppb) (3), the rare bis-substituted derivative Rh4 (CO) 8 (dppe) 2 (2), and the two unique dimeric assemblies Rh4 (CO) 10 (dpp-hexane) 2 (4) and Rh4 (CO) 10 (trans-dppe) 2 (5). The tetrahedral Rh4 core of the cluster precursor was preserved in all cases. The new compounds were characterized via infrared (IR) spectroscopy and single-crystal X-ray diffraction (SC-XRD). Furthermore, variable-temperature (VT) 31P1H NMR spectroscopy elucidated the dynamic behavior of the phosphorus atoms. This work reports a robust methodology for accessing stable, low-nuclearity rhodium phosphine clusters with tunable properties.

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