Dasarath Mal

Layered transition metal carboxylates: efficient reusable heterogeneous catalyst for epoxidation of olefins.

Layered metal carboxylates [M(malonato)(H(2)O)(2)](n) (M = Ni(II) and Mn(II)) that have a claylike structure have been synthesized hydrothermally and characterized. The interlayer separation in these layered carboxylates is comparable to that of the intercalation distance of the naturally occurring clay materials or layered double hydroxides (LDHs). In this study, we have demonstrated that, instead of intercalating the metal complex into layers of the clay or LDH, layered transition metal carboxylates, [M(malonato)(H(2)O)(2)](n), as such can be used as a recyclable heterogeneous catalyst in olefin epoxidation reaction. Metal carboxylates [M(malonato)(H(2)O)(2)](n) exhibit excellent catalytic performance in olefin epoxidation reaction.

Synthesis, characterization and observation of structural diversities in a series of transition metal based furan dicarboxylic acid systems

Six new MOFs have been synthesized by using transition metal ions and 2,5-furandicarboxylic acid, [M(fdc)(bpe)]n (M = Co(1)/Ni(2)); [M(fdc)(bpee)]n (M = Co(3)/Ni(4)); [M(fdc)(H2O)3]n (M = Mn(5)/Zn(6)), [where fdc = furan-2,5-dicarboxylic acid, bpe = 1,2-bis(4-pyridyl)ethylene, bpee = 1,2-bis(4-pyridyl)ethane]. All the compounds were characterized by single crystal X-ray analysis and show interesting diversities in their structures. Compounds 1–4 are interesting two-fold interpenetrated 3D frameworks, whereas 5 and 6 have zig-zag chains. Topological analysis on compounds 1–4 revealed that these compounds are uninodal 7-c nets with the Schlafli symbol 33.413.54.6. Compounds 1–4 were subjected for N2 adsorption study to measure the porosity of the materials. BET measurement shows that compounds 1–4 are microporous having surface areas of 128 m2 g−1. The variable temperature magnetic susceptibility measurement reveals the presence of weak interaction in the compounds.

Synthesis, crystal structures, spectral studies and reactivity of square planar copper(II) complexes containing Schiff base ligand

The reactions of HL1 [2-((2-(benzylthio)phenylimino)methyl)phenol] and HL2 [3-((2-(benzylthio)phenylimino)methyl)-2-hydroxy-5-methylbenzaldehyde] separately with Cu(OAc)2·H2O afforded new Cu(II) complexes [Cu(L1)(OAc)] (1) and [Cu(L2)2] (2), respectively. These are characterized by microanalytical data and spectroscopic studies. UV–vis spectra of the complexes show intense low-energy transitions ∼ 420 nm which are ligand to metal charge transfer (LMCT) transitions. The single-crystal X-ray structures were determined for 1 and 2. Reactions of [Cu(L1)(OAc)] (1) with , SCN– and show the replacement of weakly coordinated acetate yielding [Cu(L1)(N3)], [Cu(L1)(SCN)] and [Cu(L1)(NO2)], respectively. Unequivocal characterization of the substituted products has been done by single-crystal X-ray study of [Cu(L1)(N3)]. HL2 and its Cu(II) complex exhibited low-intensity emission bands at ∼575 nm upon excitation at 375 nm and at 420 nm, respectively. Redox properties of the complexes were determined electrochemically. Density functional theory (DFT) computations have been carried out to explain the spectroscopic and redox properties of the complexes.

Synthesis, X-ray crystal structure and magnetic study of a μ 1,5-dca bridged ferromagnetic dimeric copper(II) complex

Reaction of Cu(NO3)2 · 3H2O, 1-(N-salicyalideneimine)-2-(N,N-dimethyl)-aminoethane (HL1), LiClO4, and sodium dicyanamide (Nadca) in aqueous medium affords a dimeric complex [Cu2(L1)2 (μ1, 5-dca)](ClO4) (1). Single crystal X-ray analysis reveals that 1 is dinuclear with copper(II) ions bridged by a single dicyanamide group in end-to-end fashion. The coordination environment around copper(II) is square planar. Two nitrogens and oxygen of the tridentate Schiff-base ligand (HL1) occupy three coordination sites of the square plane while the remaining site is occupied by the nitrogen of a terminal nitrile of the bridging dca. The nitrogen of the other terminal nitrile group of the μ1,5-dca ligand connects a neighboring [CuL1] unit to yield [Cu2(L1)2(μ1,5-dca)](ClO4) (1). Variable temperature magnetic susceptibility measurements show that the magnetic interaction is ferromagnetic (J = 1.93 cm−1). The results of a magnetic model are in good agreement with the experimental data.

Synthesis, characterisation and X-ray structure of an azido adduct of a tridentate (NNO) Schiff base nickel(II) complex

The tridentate Schiff base 1-(N-salicylideneimino)-2-(N,N-diethyl-aminoethane (HL), derived from the condensation of salicylaldehyde with N,N-diethylethylenediamine, reacted with nickel(II) nitrate and azide to give a mononuclear complex of formula [Ni(L)(N3)], where HL = Et2N(CH2)2NCHC6H4(OH). The complex was characterized by spectroscopic and X-ray crystallographic methods. Coordination around nickel(II) is square planar. The molecular and supramolecular structure of the complex is discussed.

Layered transition metal carboxylates: synthesis, structural aspects and observation of multi-step magnetic transition through phase diagram†

Two new layered transition metal carboxylate frameworks, [Co3(L)2(H2O)6]·2H2O () and [Ni3(L)2(H2O)6]·2H2O () (L = tartronate anion or hydroxymalonic acid), have been synthesized and characterized by X-ray single crystal analysis. Both compounds have similar 2D structures. In both compounds there are two types of metal centers where one center is doubly bridged by the alkoxy oxygen atoms through μ2-O bridging to form a 1D infinite chain parallel to the crystallographic b-axis with the corners shared between the metal polyhedra. Magnetic susceptibility measurements revealed the existence of antiferromagnetic short range correlations between Co(Ni) intra-chain metal centers (with exchange constants JCo = -22.6 and JNi = -35.4 K). At low temperatures, long range order is observed in both compounds at Néel temperatures of 11 (for ) and 16 (for ) K, revealing that other exchange interactions, rather than the intra-chain ones, play a role in these systems. Whereas compound has an antiferromagnetic ground state, compound exhibits a ferromagnetic component, probably due to spin canting. Isothermal magnetization data unveiled a rich phase diagram with three metamagnetic phase transitions below 8 K in compound .

A comparative study of crystal structure of a Cu(II) dicyanamide compound determined independently from X-ray powder-and single-crystal analyses

Abstract The dicyanamido diethelenetriamine copper (II) compound, C8H13CuN9 (I), has been synthesized, and structurally characterized independently using X-ray powder- and single-crystal diffraction data. The direct methods program package EXPO-2004 has been used for structure solution from laboratory powder diffraction data. Intermolecular N—H···N hydrogen bonds in (I) generate R22(16) rings, which are fused forming molecular columns propagating along the [100] direction. Further linking of parallel columns through N—H···N hydrogen bonds results into a three-dimensional supramolecular network.

CCDC 909525: Experimental Crystal Structure Determination

Related Article: Dasarath Mal, Rupam Sen, Paula Brandao, Zhi Lin|2013|Inorg.Chem.Commun.|30|111|doi:10.1016/j.inoche.2013.02.001

Bis(2,2′-bipyridine-κ2N,N′)bis­(dicyan­amido-κN1)cadmium

In the title compound, [Cd(C2N3)2(C10H8N2)2], the CdII ion is coordinated in a distorted octahedral environment by four N atoms from two chelating 2,2′-bipyridine ligands and two N atoms from two monodentate dicyanamide ligands. The dihedral angle between the mean planes of the two bipyridine ligands is 87.67 (6)°.

Bis(2,2′-bipyridine-κ2N,N′)bis(dicyanamido-κN1)cadmium

In the title compound, [Cd(C2N3)2(C10H8N2)2], the CdII ion is coordinated in a distorted octahedral environment by four N atoms from two chelating 2,2′-bipyridine ligands and two N atoms from two monodentate dicyanamide ligands. The dihedral angle between the mean planes of the two bipyridine ligands is 87.67 (6)°.