Steric and electronic influence of Re(I) tricarbonyl complexes with various coordinated β-diketones

Re(I) tricarbonyl complexes, with coordinated ,B-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 (theta) were calculated as 141.93 degrees, 148.77 degrees, and 149 degrees; and compared to the Equivalent cone angles obtained from DFT calculations. These were 131.25 degrees, 134.34 degrees, and 134.28 degrees 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 ,B-diketonato ligands increase. In general, the theoretical and experimental Re-P and Re-O-OO bond distances compared well among the complexes , with the most significant deviation occurring for 4 (relative differences of 0.055 angstrom (Re-P) and 0.015 angstrom (average Re-O)). Hirshfeld surface analysis was used to obtain the fingerprint plots, and the Hirshfeld surfaces were mapped with d(norm) for 4, 5 , and 6 . (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, three new Re(I) crystal structures were reported and characterized using analytical tools. The analysis revealed that the Re-P bond distances decrease with an increase in the number of electron-withdrawing groups, and the theoretical and experimental results were in good agreement.