Steric and electronic influence of Re(I) tricarbonyl complexes with various coordinated β-diketones
Manicum, Amanda-Lee Eza Schutte-Smith, Marietjie Malan, Frederick P. Visser, Hendrik Gideon
Manicum, Amanda-Lee Eza
Schutte-Smith, Marietjie
Malan, Frederick P.
Visser, Hendrik Gideon
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Abstract
Re(I) tricarbonyl complexes, with coordinated β-diketones, are the center of attention as they form part of a library of promising cancer therapeutic and diagnostic agents. In this study, we present three new Re(I) crystal structures. {fac [Re(Benzac)(CO)3(PCy3)] (4), fac-[Re(Tfaa)(CO)3(PCy3)] (5), and fac-[Re(Hfaa)(CO)3(PCy3)] (6); benzoylacetone = Benzac; trifluoroacetylacetone = Tfaa and hexafluoroacetylacetone = Hfaa; PCy3 = tricyclohexylphosphine}. The three reported complexes were synthesized with ease and good yield, involving the "2 + 1" mixed ligand approach. The complexes were characterized using analytical tools: IR, NMR, UV/Vis, single-crystal X-ray diffraction. The Tolman cone angles (θ) were
calculated as 141.93°, 148.77°, and 149°; and compared to the Equivalent cone angles obtained from DFT calculations. These were 131.25°, 134.34°, and 134.28° for (4), (5), and (6), respectively. The DFT analysis observed that the Re-P bond distances decrease as the number of electron-withdrawing groups (CF3) on the β-diketonato ligands increase. In general, the theoretical and experimental Re-P and Re-OOO bond distances compared well among the complexes, with the most significant deviation occurring for 4 (relative differences of 0.055 A˚ (Re-P) and 0.015 A˚ (average Re-O)). Hirshfeld surface analysis was used to obtain the fingerprint plots, and the Hirshfeld surfaces were mapped with dnorm for 4, 5, and 6.
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Date
2022-05-09
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Elsevier
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Keywords
Re(I) tricarbonyl, β-diketones, tricyclohexylphosphine, Tolman cone angle, DFT calculations