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RESEARCH PRODUCT

Structural characterization of triorganotin(IV) complexes with sodium fusidate and DFT calculations

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Abstract Three new complexes of the steroid sodium fusidate (sodium 2-[(1 S ,2 S ,5 R ,6 S ,7 S ,10 S ,11 S ,13 S , 14 Z ,15 R ,17 R )-13-(acetyloxy)-5,17-dihydroxy-2,6,10,11-tetramethyl tetracyclo[8.7.0.0 2,7 .0 11,15 ] heptadecan-14-ylidene]-6-methylhept-5-enoate = (NaFusidate, Na FA )]), with triorganotin(IV) moieties have been prepared and investigated by conventional techniques as FTIR, Mossbauer, ESI-MS and NMR spectroscopy. The isolated compounds showed stoichiometries organotin(IV)/fusidate 1/1, R 3 Sn(IV) FA (R = Me, FA1 ; Bu, FA2 ; Ph, FA3 ). The ligand coordination sites were determined by FTIR spectroscopic measurements. In the complexes, the carboxylate group of the fusidate ligand behaves as monodentate monoanionic donor, binding the Sn(IV) through one oxygen atom. On the basis of C–Sn–O COO angles, calculated through the rationalization of the 119 Sn Mossbauer parameter nuclear quadrupole splitting, it has been confirmed that, in all the solid state complexes, the Sn(IV) was tetracoordinated in a distorted tetrahedral structure. Further data from 119 Sn CP-MAS spectra confirmed the distorted tetrahedral arrangement. In MeOH solution, 1 H, 13 C and 119 Sn NMR spectroscopy showed monomeric complexes, where the carboxylate group mainly acts as monodentate ester-type ligand, and the occurrence of a coordinated solvent molecule to the tin center, as validated by non-relativistic NMR DFT study.