Rajesh Chakrabarty

Self-Assembly of a Pd6-Molecular Double-Square and a Cu3-Trigonalbipyramidal Cage via a New Tripodal Flexible Ligand

A new tripodal flexible ligand (L) containing pyrazolyl functionality has been prepared and successfully used to obtain a pd(6) (1) molecular double-square and a cu(3) trigonalbipyramidal cage (2), where complex 1 represents the first example of a double-square obtained using a flexible tripodal ligand.

Structural, thermal and spectroscopic properties of supramolecular coordination solids

Molecules in metal isonicotinate tetrahydrates, M(NC5H4-p-CO2)2.4H2O with M = Mn, Fe, Co, Ni, Cu, Zn, consisting of the hexacoordinate complexestrans-[M(NC5H4-p-CO2)(OH2)4], participate in exhaustive hydrogen-bond formation among themselves to lead to a robust 3D supramolecular network in the solid state. Solid-state diffuse reflectance UV-Vis-NIR spectra of the complexes have been assigned to ligand field and charge transfer transitions. Sharp weight loss due to dehydration, as shown by TGA of Cu(NC5H4-p-CO2)2.4H2O, suggests the suitability of this complex for the gravimetric estimation of copper.

Catalytic Properties of Cobalt(III)−Oxo Cubanes in the TBHP Oxidation of Benzylic Alcohols

Two series of oxo-bridged Co(III) complexes of the type Co(4)O(4)(O(2)CC(6)H(4)-X)(4)(py)(4) (1) and Co(4)O(4)(O(2)CC(6)H(4)-X)(4)(4-Mepy)(4) (2), where X = H (a), Me (b), MeO (c), Cl (d), NO(2) (e), have been synthesized and characterized in detail. The molecular structures of the complexes consist of a cubelike Co(4)(mu(3)-O)(4) core having Co and O atoms at alternate vertices with carboxylato ligands bridging the Co(3+) ions along four face diagonals of the approximate cube. Nitrogen atoms from pyridyl ligands complete the distorted-octahedral coordination around each Co(III). These neutral Co(III) complexes undergo a nearly reversible one-electron oxidation involving the redox couple [Co(4)(III)(mu(3)-O)(4)](4+) <--> [Co(3)(III)Co(IV)(mu(3)-O)(4)](5+) at potentials (approximately 0.7-1.0 V) that linearly depend on the electronic influence of X. The cobalt(III) clusters of types 1 and 2 have been found to effectively promote the TBHP oxidation of benzylic alcohols under homogeneous conditions to produce the corresponding carbonyl compounds.

Enhanced selectivity in green catalytic epoxidation using a supported cobalt complex

A supported reagent made by immobilising a tetrameric cobalt(III) cubane cluster on mesoporous silica catalyses the aerobic oxidation of α-pinene with enhanced epoxidation selectivity compared with other systems.