Nirmal Kumar Karan

Synthesis, characterisation and structural studies of [Cu(dach)(μ-NCS)(NCS)]n and [Cu(dach)2(N3)]ClO4 (dach = 1,4-diazacycloheptane)

Abstract A new singly bridging complex [Cu(dach)(μ-NCS)(NCS)] n (dach=1,4-diazacycloheptane) has been synthesised and its crystal structure determined. There are many examples of double NCS bridged polymeric chains, but fewer singly bridged ones. IR, ESR and temperature variable magnetic studies are described but no magnetic interaction was found between the copper centres. [Cu(dach) 2 (N 3 )]ClO 4 has also been characterised by IR, ESR spectra and magnetic studies. The crystal structure determination shows that it is a penta-coordinated monomeric species with an axially coordinated azide linked to the perchlorate counterion by hydrogen bonding.

Synthesis and structural characterization of a (N,N′-bis[2(S)-pyrrolidylmethyl]-propane-1,3-diamine) nickel (II) complex

The nickel(II) complex [Ni(C4H3NCH=N–(CH2)3–N=CHC4H3N)], (1) containing the symmetrical N4 tetradentate Schiff base ligand, which is the 2:1 condensation product of pyrrole-2-carboxaldehyde and 1,3-diaminopropane respectively, was prepared. Structural investigation shows that it is monomeric, having space group P21/c, a = 7.989(7), b = 17.406(14), c = 9.193(5) Å, α = 90, β = 100.39(6), γ = 90○, and Z = 4. The coordination geometry around the nickel atom is slightly distorted square planar and the conformation of the six-membered ring containing the metal,azomethine nitrogens and three carbon atoms of the connecting 1,3-diaminopropane is a symmetric boat.

A new cyano-bridged Ca(II)–Fe(III) complex containing both molecular square and linear trimetallic species

Abstract A new cyano-bridged Ca(II)–Fe(III) complex, [Ca2(phen)4(H2O)6Fe(CN)6][{Ca(phen)2(H2O)2Fe(CN)6}2]·3(phen)·(phenH)·14H2O·CH3OH (where phen=1,10-phenanthroline) 1 has been synthesized and structurally characterized. It contains a cyano-bridged trimetallic cationic species [Ca2(phen)4(H2O)6Fe(CN)6]+ 1a with a nearly linear Ca–Fe–Ca arrangement, and an anionic species [{Ca(phen)2(H2O)2Fe(CN)6}2]2− 1b which has a cyano-bridged tetrametallic Ca–Fe–Ca–Fe molecular square framework. In both the species, the Ca atoms are eight coordinated with distorted anti-squareprismatic geometry and the Fe atoms have six coordinated octahedral geometry. The charge is balanced by the protonation of one phen molecule in the lattice.

A novel trinuclear cyano-bridged calcium(II)-iron(III) complex; [(phen)2(H2O)2CaNC(NC)4FeCNCa(OH2)(Phen)2NO3].H2O

Abstract A new trimeric cyano-bridged complex [(Phen)2(H2O)2CaNC(NC)4FeCNCa(OH2)(Phen)2NO3]·H2O (1) (where phen=1,10-phenanthroline) has been synthesised and its crystal structure is determined by single crystal X-ray diffraction. The behaviour of the nitrate anion in this structure is noticeable. It seems that 50% of the time, this anion is coordinating in the monodentate mode and 50% in the bidentate mode. The structure features a central [Fe(CN)6]3− unit that links a [Ca(Phen)2(OH2)2]2+ dication and a [Ca(Phen)2(OH2)(NO3]+ cation via two trans-cyanide bridges. Each Ca atom is seven coordinated and achieves a capped octahedral geometry. Both intramolecular and intermolecular hydrogen-bonding interactions are present in the structure leading to the formation of a cohesive three-dimensional network.

A novel maze-type network assembled by copper(II) and 2,2′-dicarboxydiphenylthioether: [(Cu4(C5H5N)8{S(C6H4CO2)2}4(H2O)2]·2H2O)n

Abstract A novel polymeric copper(II) complex ([Cu4(C5H5N)8{S(C6H4CO2)2}4(H2O)2]·2H2O)n assembled by 2,2′-dicarboxydiphenylthioether and pyridine and bridged by carboxylato groups has been synthesised and structurally characterised by single crystal X-ray structural studies. The maze-type structure contains one tetranuclear 40- and one dinuclear 8-membered metallocycles, both of which are centrosymmetric and form the repeat unit in the polymer chain.

A novel cyano-bridged Sr(II)–Fe(III) polymer containing alternating octanuclear and tetranuclear cores

Abstract A novel cyano-bridged Sr(II)–Fe(III) polymeric complex ([Sr3(phen)6(H2O)6{Fe(CN)6}2]·phen·6.5H2O)n (1) has been synthesized and structurally characterized. The complex contains alternating octanuclear 24-membered and tetranuclear 12-membered metallocycles, which are repeated to form a polymeric chain. The Sr(II) centres are eight coordinated with distorted bicapped trigonal prismatic geometry while the Fe(III) centres have six coordinate octahedral geometry.

Doubly end-on azido bridged mixed-valence cobalt trinuclear complex: spectral study, VTM, inhibitory effect and antimycobacterial activity on human carcinoma and tuberculosis cells

Doubly end-on azido-bridged mixed-valence trinuclear cobalt complex, [Co3(L)2(N3)6(CH3OH)2] (1) is afforded by employing a potential monoanionic tetradentate-N2O2 Schiff base precursor (2-[{[2-(dimethylamino)ethyl]imino}methyl]-6-methoxyphenol; HL). Single crystal X-ray structure reveals that in 1, the adjacent Co(II) and Co(III) ions are linked by double end-on azido bridges and thus the full molecule is generated by the site symmetry of a crystallographic twofold rotation axis. Complex 1 is subjected on different spectral analysis such as IR, UV-vis, emission and EPR spectroscopy. On variable temperature magnetic study, we observe that during cooling, the χMT values decrease smoothly until 15K and then reaches to the value 1.56 cm(3) K mol(-1) at 2 K. Complex 1 inhibits the cell growth on human lung carcinoma (A549 cells), human colorectal (COLO 205 and HT-29 cells), and human heptacellular (PLC5 cells) carcinoma cells. Complex 1 exhibits anti-mycobacterial activity and considerable efficacy on Mycobacterium tuberculosis H37Rv ATCC 27294 and H37Ra ATCC 25177 strains.

A New Polymeric Barium-Iron (III) Complex with Chain and Large Ring Structure

The compound {[Ba6(Phen)12(CF3COO)6{Fe(CN)6}2(H2O)8]·6 H2O}n (1) (Phen = 1,10-phenanthroline) has been synthesized and structurally characterized. In the crystal structure, the two consecutive Ba centres are bridged through trifluoroacetate groups and also via cyano groups of [Fe(CN)6]3− and form the zigzag chain resulting the formation of 24-membered ring structure. The Ba-centres are 8-fold coordinated with distorted cubic geometry. Six H2O molecules per asymmetric unit remain in the structure without any direct interaction with the metal atoms but they act in hydrogen bond formation.

Synthesis, Characterisation and Crystal Structure of a Cyano-Bridged Polymeric Yttrium-Iron Complex {[Y(phen)2(H2O)2Fe(CN)6]·8H2O}n

A new cyano-bridged 1D polymeric linear chain complex {[Y(phen)2(H2O)2Fe(CN)6]ּ 8H2O}n (where phen = 1,10-phenanthroline) has been synthesised and its crystal structure determined. The yttrium(III) and iron(III) centres achieve distorted square antiprismatic and slightly distorted octahedral geometry, respectively. Presence of an extensive network of hydrogen bonds present in the complex impart the overall stability to the system. The presence of ten water molecules per molecular unit has been confirmed by thermogravimetric analysis.

A New Trinuclear Cyano-Bridged Sr-Fe(III) Complex, [Sr2(phen)4(H2O)3(NO3)Fe(CN)6] · H2O

1 A new cyano-bridged trinuclear complex [Sr2(phen)4(H2O)3(NO3)Fe(CN)6] · 1.25 H2O () (where phen = 1,10-phenanthroline) has been synthesised and its crystal structure determined. The structure features a central [Fe(CN)6]3- unit that links a [Sr(phen)2(OH2)2]2+ dication and a [Sr(phen)2(OH2)(NO3)]+ monocation via two trans cyanide bridges. In the dicationic part, the Sr centre achieves a pentagonal bipyramidal geometry whereas in the monocationic part, the Sr centre shows a square antiprismatic geometry. The presence of an extensive network of hydrogen bonds imparts the overall stability to the system.