Sumitava Khan

Crystallographic Evidence for Reversible Symmetry Breaking in a Spin‐Crossover d7 Cobalt(II) Coordination Polymer

This work was supported by the DST and CSIR, India. J.S.C. thanks the Spanish MICINN through CTQ2009-06959 for the research fellowship “Juan de la Cierva” (18-08-463B-750). J.R. also thanks the Spanish MICINN through CTQ2009-07264.

Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a pentadentate N-donor Schiff base

AbstractOne-pot synthesis using a 2:2:1:2 molar ratio of Pb(OAc)2·3H2O, L, piperidinum terephthalate (ptp) and NaClO4/NH4PF6 at room temperature affords two dinuclear compounds of the type [Pb2(L)

An anti-ferromagnetic terephthalate-bridged trigonal prismatic dinuclear manganese(II) complex: Synthon of rare anion⋯π interaction promoting dimensionality

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Syntheses, structures and magnetic properties of μ1,5 dicyanamide bridged coordination polymers of copper(II) and nickel(II) containing a tetradentate N-donor Schiff base

-tp)](ClO4/PF6)2 (1/2) [L=N,N′-(bis-(pyridin-2-yl)benzylidene)diethylenetriamine and tp = terephthalate dianion]. The compounds are characterized by microanalytical, spectroscopic, thermal and other physicochemical results. X-ray structural analyses of 1 and 2 reveal that each heptacoordinated lead(II) centre with a PbN5O2 chromophore are bound by five N atoms of L and connected through O atoms of a bis(bidentate) tp bridge. The arrangements of L and tp suggest a gap around the metal centre due to occupation of a stereo-active lone pair of electrons reflecting a hemidirected coordination around the metal centre. The complexes exhibit reasonable thermal stabilities with the tolerate temperatures ca. 255°C for 1 and 263°C for 2. The complexes display intraligand (π-π*) fluorescence in the solid state and in DMF solutions at room temperature. Graphical AbstractTwo dinuclear lead(II) compounds are isolated and X-ray crystallographically characterized. Each heptacoordinated metal(II) center adopts a hemidirected environment and connected through bis(bidentate) terephthalate bridge. The complexes exhibit intraligand 1(π-π*) fluorescence in the solid state and in DMF solutions at room temperature.

Syntheses, structures and magnetic properties of μ1,5-dicyanamide bridged di- and polynuclear manganese(II) complexes containing neutral N-donor Schiff bases: Control of coordination number and nuclearity by varying denticity

AbstractA dinuclear compound [Mn2(L)2(μ-tp)](PF6)2⋅3.57H2O (1) [L = N,N′-(bis(pyridin-2-yl)benzy-lidene)-1,3-propanediamine and tp = terephthalate dianion] has been isolated and characterized on the basis of microanalytical, spectroscopic and other physicochemical properties. X-ray structural study showed interesting bis(bidentate) bridging motif of tp in the dicationic dinuclear unit [Mn2(μ-tp)]2+. Each manganese(II) centre adopts a rare distorted trigonal prismatic geometry with an MnN4O2 chromophore. Chelation of the tetradentate Schiff base (L) along with bis(bidentate) bridging of two O atoms of tp complete hexacoordination around each manganese(II) centre. The dinuclear units of 1 are associated through cooperative C-H⋯F hydrogen bonds and π⋯π, C-H⋯π and rare anion⋯π interactions to promote the dimensionality in a graded manner. Variable temperature magnetic susceptibility measurement of 1 in the 2–300 K temperature range revealed weak anti-ferromagnetic interaction presumably due to long bridging arm of tp. Graphical AbstractSynthesis, crystal structure and magnetic behavior of a dinuclear manganese(II) terephthalate complex with tetradentate N-donor Schiff base has been described. Interesting trigonal prismatic geometry around metal ion was observed in the complex. The dinuclear units of 1 are the source of rare anion⋯π interactions to promote the dimensionality of compound.