Synthesis, structural, photophysical and thermal studies of benzoate bridged Sm(III) complexes

One samarium coordination polymer (chain like) 1 with composition [{Sm(OBz)3(MeO)2}2]n has been prepared from the reaction of SmCl3 and sodium benzoate in 1:3 ratio whereas four binuclear samarium complexes with chemical composition [{(tp)Sm(μ-p-X-OBz)2}2] have been prepared by the reaction of SmCl3, potassium hydrotris(pyrazol-1-yl)borate [K(tp)] and sodium p-X-benzoate (where X = H, Cl, F, NO2) in 1:1:2 ratio. These complexes have been characterized by elemental analysis, IR spectroscopy, thermogravimetry, optical properties, X-ray and magnetic measurement studies. The X-ray structure shows that the complexes 2–5 are isostructural whereas the structure of 1 is different. The coordination number around metal center in 1 is eight whereas in complexes 2–5, each samarium is seven coordinate. The X-ray studies indicate that the complex 1 crystallizes in monoclinic space group P2(1)/c with the cell dimensions a = 9.75(7), b = 21.83(15), c = 22.28(15) Å, whereas the complexes 2 and 3 crystallizes isostructurally in the triclinic space group P1¯ with the cell dimension a = 11.77(10), b = 12.60(10), c = 17.57(13) Å and a = 9.55(3), b = 12.80(4), c = 14.47(5) Å, respectively. The samarium ions in 2 and 3 are coordinated by three N atoms of pyrazolylborate ligand and four O atoms from benzoate groups. The photophysical properties of above complexes have been studied with ultraviolet absorption, excitation and emission spectral studies. The complexes 1–5 excited at 240 nm wavelength produced characteristic luminescence features, arising mostly due to the f–f transitions.