Two new bis- and mono-tridentate chelated iron complexes, [FeII(LH)2](ClO4)2·C2H5OH (1) and [FeIII(LH)Cl3]·0.5CH2Cl2 (2), with facially capping N-tridentate ligand, 2-(5,7-dihydro-6H-dibenzo[c,e]azepin-6-yl)-N-(pyridin-2-ylmethyl)ethan-1-amine, incorporating biphenyl-append (LH), have been synthesized and characterized by X-ray crystal structure, spectroscopic (FTIR, UV–Vis and ESI-MS) and magnetic susceptibility measurements. Structure of 1 reveals pseudo-octahedral geometry around Fe(II) with two ligands (LH) arranged in trans-facial manner, in two crystallographic independent molecules, Mol. A and Mol. B, differing in biphenyl twist angles, ϕ = 43.7° and 45.1°. Complex 2 has similar geometry with Fe(III) having one facially capping ligand, LH and three chlorides (Cl−), also in two crystallographic independent molecules, Mol. A and Mol. B, differing by biphenyl twist angles, ϕ = 40.9° and −42.7°. The UV–Vis absorption spectrum of 2 in CH3CN suggests competitive coordination between the two weakly-coordinating tertiary amine nitrogen atoms having biphenyl-append, and the solvent, CH3CN. The qualitative magnetic susceptibility measurements for 1 and 2 at 296 K provide moments of 4.2 μB and 2.7 μB, respectively, suggesting nearly high-spin, Fe(II) (S = 2) and a rare intermediate-spin, Fe(III) (S = 3/2). © 2018 Elsevier Ltd

Narasimha N. Murthy

Department Of Chemistry

Nisha Chetty

Venkatachalam Ramkumar

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Polyhedron

Bis- and mono-tridentate chelated iron complexes with a new facially capping unsymmetrical nitrogen ligand: X-ray structural and spectroscopic studies

Two simple biphenyl-Appended (2-pyridyl)alkylamine N-bidentate ligands, Le and Lm, having ethylene and methylene spacers between donor groups, with bite angles Le â 100° and Lm â 80°, dictate pseudotetrahedral and trigonal-bipyramidal geometries in six high-spin Ni(II)-halide complexes, [Ni(Le)X2] and [Ni(Lm)2X](ClO4) (where X = Cl-, Br-, I-), respectively. The structures in the solid state, determined using X-ray crystallography, and in solution, determined using spectroscopic methods (UV-vis-NIR and paramagnetic 1H NMR), which complement each other, are described. © 2017 American Chemical Society.

Fulltext

ACS Omega

Bite-Angle-Regulated Coordination Geometries: Tetrahedral and Trigonal Bipyramidal in Ni(II) with Biphenyl-Appended (2-Pyridyl)alkylamine N,N′-Bidentate Ligands

Treatment of the novel biphenyl-appended N,N′-bidentate ligand, 6-(2-pyridylmethyl)-6,7-dihydro-5H-dibenzo[c,e]azepine with FeX2 (X&nbsp;=&nbsp;Cl-, Br−) affords two stable four-coordinate, pseudo-tetrahedral [Fe(NN′)X2] (where X&nbsp;=&nbsp;Cl−, 1; Br−, 2) complexes. In contrast, the same reaction in the presence of pseudo-halides, KNCS/Se, gives two six-coordinate distorted-octahedral, [trans-Fe(NN′)2(NCE)2] (where E&nbsp;=&nbsp;S, 3; Se, 4) complexes. All the four complexes were characterized by X-ray crystallography, spectroscopic (FTIR, Uv–Vis, paramagnetic 1&nbsp;H NMR, Mossbauer of 1) methods, ESI-MS and variable-temperature magnetic susceptibility measurements (VSM, 20–300&nbsp;K). The molecules in the crystal lattice are held together by several strong intermolecular hydrogen-bonding, π⋯π stacking (py-py or py-ph) and C–H⋯π (CH2-ph) interactions. The strong absorption spectral features of 3 and 4 in solution and the paramagnetic 1H NMR spectra of 1–4 are interpreted. Variable-temperature magnetic susceptibility measurements of solids 1–4 show magnetic moment values near 4.9 B.M., characteristic of temperature-independent high-spin (S&nbsp;=&nbsp;2) state for Fe(II). Mossbauer spectrum of 1 complements this property. The monomeric nature of 1 and 2 is an attractive feature, which may serve as invaluable precursor to model the active-site structure and function of mononuclear non-heme iron oxidase (MNO) enzymes, involved in O2 activation and oxidation catalysis of aromatic organic substrates. © 2017

Inorganica Chimica Acta

High-spin iron(II) complexes of halides and pseudo-halides with biphenyl-appended N,N′-bidentate ligand: X-ray structural and spectroscopic studies

Facile hydrolysis of a phosphodiester promoted by a dicopper bis(μ-hydroxo) complex containing a new biphenyl appended N-bidentate ligand led to the isolation of the first example of hexameric copper pyrophosphate through 'in situ self assembly'. © 2009 The Royal Society of Chemistry.

Journal	Data powered by TypesetPolyhedron
Publisher	Data powered by TypesetElsevier Ltd
ISSN	02775387
Open Access	No