Biswarup Sarkar

Copper(II) azide complexes with mono-anionic tridentate Schiff-base ligands: monomer versus dimer

Three new copper(II) complexes [CuL1N3]2 (1), [CuL2N3] (2) and [CuL3N3] (3) with three very similar tridentate Schiff base ligands [HL1 = 6-diethylamino-3-methyl-1-phenyl-4-azahex-3-en-1-one, HL2 = 6-amino-3-methyl-1-phenyl-4-azahex-3-en-1-one and HL3 = 6-amino-3-methyl-1-phenyl-4-azasept-3-en-1-one] have been synthesized and structurally characterized by X-ray crystallography. In complex 1 half of the molecules are basal-apical, end-on azido bridged dimers and the remaining half are square-planar monomers whereas all the molecules in complexes 2 and 3 are monomers with square-planar geometry around Cu(II). A competition between the coordinate bond and H-bond seems to be responsible for the difference in structure of the complexes.

Copper(II) complexes with singly condensed tridentate Schiff-base ligands incorporating 1-benzoylacetone

Two copper(II) complexes [CuL1Cl]n (1) and [CuL2Cl] (2) with singly condensed tridentate Schiff-base ligands [HL1 = 6-amino-3-methyl-1-phenyl-4-azahex-3-en-1-one and HL2 = 6-diethylamino-3-methyl-1-phenyl-4-azahex-3-en-1-one] have been synthesized and structurally characterized by X-ray crystallography. Complex 1 is a single-chloro-bridged one-dimensional polymer, whereas 2 is a monomeric square-planar complex. The H-bonding interactions of the amine hydrogen and the non-bonding interactions of phenyl groups in the Schiff base play important roles for the structural variations.