The coordination behaviour of the novel ligand, HMPz4Cy, is reported, together with solid state isolation of its diamagnetic cobalt(III) complexes, [Co(MPz4Cy)2]X·nH2O (X = Cl, Br, NO3, ClO4 and BF4). I.r. and 1H-n.m.r. data for the free ligand and its CoIII complexes confirm that the ligand, HMPz4Cy, acts as a uninegative anion with NNS tridentate function via the pyrazolyl nitrogen (tertiary), azomethine nitrogen and thiol sulphur. Electronic spectra (both solid and solution) are commensurate with a distorted octahedral environment for the reported CoIII species. Cyclic voltammograms of CoIIIcomplexes indicate a quasireversible Co+3/Co+2 couple. X-ray crystallography of a representative species, [Co(MPz4Cy)2]Cl·2.75H2O (C2, monoclinic), has shown unambiguously that the two ligands are orthogonally coordinated to the central CoIII ion with both the thiolato sulphurs and both pyrazolyl nitrogen atoms in cis positions.

D K SAU

N SAHA

R J BUTCHER

S CHAUDHURI

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Synthesis, spectroscopy and cyclic voltammetry of cobalt(III) complexes with 5-methyl-3-formylpyrazole N(4)-cyclohexylthiosemicarbazone (HMPz4Cy): X-ray crystal structure of [Co(MPz4Cy)2]Cl.2.75H2O

Transition Metal Chemistry

New iron(III) complexes of 5-methyl-3-formylpyrazole 3- hexamethyleneiminylthiosemicarbazone (HMPz3Hex), [Fe(MPz3Hex)2]X • nH2O (where X = Cl, NO3or ClO4 and n = 1-2) have been synthesized and physico-chemically characterized by magnetic data (polycrystalline state), electronic, i.r. and e.p.r. spectral studies. The reported complexes are all cationic electrolytes (1:1) containing two moles of monodeprotonated title ligand and an anionic counterpart. I.r. spectra (4000-200 cm-1) indicate coordination to the central iron(III) ion via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulphur atoms of the primary ligand molecule. E.p.r. data (r.t. and l.n.t.) show the presence of a low-spin iron(III) cation with d xz 2 d xz 2 d xz 1 configuration. Cyclic voltammograms of iron(III) complexes indicate a reversible Fe +3/Fe+2 couple. X-ray data of [Fe(MPz3Hex) 2]ClO4 • 2H2O (P1, triclinic) authenticate a FeN4S2 distorted octahedral coordination with the two azomethine nitrogens trans to each other; the pyrazolyl nitrogens and thiolato sulphurs are in cis-positions, indicating an unusual rotation about the azomethine (C=N) double bond of the free HMPz3Hex during complexation with iron(III). © Springer 2005.

Synthesis, spectroscopy and cyclic voltammetry of new iron(III) complexes with 5-methyl-3-formyl pyrazole 3-hexamethyleneiminyl thiosemicarbazone (HMPz3Hex): X-ray crystallographic identification of [Fe(MPz3Hex) 2]ClO4 Â· 2H2O with an indication for unusu

The coordinating properties of the title ligand, 5-methyl-3-formyl pyrazole 3-hexamethyleneiminyl thiosemicarbazone (HMPz3Hex), synthesized and characterized (elemental analysis, MS, IR, 1H and 13C NMR and X-ray crystallography) for the first time, are reported by solid-state isolation of cobalt(III) complexes, [Co(MPz3Hex)2]X·nH 2O (X=Cl, Br, NO3, ClO4 or BF4; n=1to2). The reported complex species have been spectroscopically characterized with X-ray structural identification of [Co(MPz3Hex)2] Br·H2O. IR and NMR data (1H and 13C) for the free ligand and its CoIII complexes confirm that the ligand, HMPz3Hex, behaves as a uninegative anion with NNS tridentate function via the pyrazolyl tert-nitrogen, azomethine nitrogen and thiol sulfur. Electronic spectral data recommend a distorted octahedral environment for the six-coordinate CoIII species. X-ray crystallography of [Co(MPz3Hex)2]Br·H2O (C2/c, monoclinic), has shown unambiguously that the crystallographic asymmetric unit consists of a [Co(MPz3Hex)2]+ cation and one Br- anion with one H2O molecule as solvent of crystallization. The two NNS ligands coordinate orthogonally to the central CoIII ion with mer-configuration. A critical scrutiny of the X-ray data of free HMPz3Hex (Pna21, orthorhombic) and [Co(MPz3Hex)2]Br·H 2O indicates that an unusual rotation about the azomethine (C=N) double bond occurs during complexation with CoIII. A plausible reaction mechanism for the same has been proposed. Sulfur is involved in a C(7)-H(7)⋯S(1) intramolecular contact restricting the conformation of the ligand both in free and its complexed form. © 2003 Elsevier Ltd. All rights reserved.

Polyhedron

Synthesis and spectroscopic characterization of new cobalt(III) complexes with 5-methyl-3-formyl pyrazole 3-hexamethyleneiminyl thiosemicarbazone (HMPz3Hex): X-ray crystallographic identification of HMPz3Hex and [Co(MPz3Hex)2]BrÂ·H2O with evidence for unu

Two new cobalt(III) complexes with S-benzyl-β-N-(5-methylpyrazole-3-yl)methylenedithiocarbazate (H2L), [Co(HL)2]NO3·EtOH (1) and [Co(HL)(L)]·H2O (2), have been synthesised and characterised using single-crystal X-ray diffraction and spectroscopic (electronic, IR and NMR) techniques. The structure of 1 consists of [Co(HL)2]+ cation and NO3-anion linked by an ethanol solvent molecule, that of 2 consists of neutral monomeric species [Co(HL)(L)] with one mole water of crystallisation where the two ligand molecules are uniquely non-equivalent. In both the complexes the coordination geometry about cobalt is distorted octahedral and the two ligands are in the mer configuration (S and tertiary N atom cis to each other and the iminic N atoms trans). © 2002 Elsevier Science Ltd. All rights reserved.

Synthesis and spectroscopic characterisation of cobalt(III) complexes with S-benzyl-Î²-N-(5-methylpyrazole-3-yl)methylenedithiocarbazate (H 2 L): X-ray structures of [Co(HL) 2 ]NO 3 Â·EtOH (1) and [Co(HL)(L)]Â·H 2 O (2)

New iron(III) complexes of 5-methyl-3-formylpyrazole-N(4)-dipropylthiosemicarbazone (HMPzNPr2) and 5-methyl-3-formylpyrazole-N(4)-dibutylthiosemicarbazone (HMPzNBut2), [Fe(MPzNPr2)2]NO3·H 2O (I) and [Fe(MPzNBut2)2]ClO4·H 2O (II), respectively, have been synthesised for the first time and physico-chemically characterised by magnetic measurements (polycrystalline state), electronic, IR and EPR spectra. Both are cationic complexes containing two monodeprotonated tridentate ligands with NNS donor sites and an anionic counterpart; the complex species behave as 1:1 electrolytes in MeOH. IR spectra (4000-200 cm-1) indicate the co-ordination to central iron(III) via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulphur atom. EPR data (RT and LNT) reveal the presence of a spin-paired iron(III) cation with d2xz d2yz d1xy configuration. X-ray crystallographic data of I and II (both P1̄, triclinic) have authenticated a FeN4S2 octahedral co-ordination in both the complex ions, as envisaged from spectral data. In both species, the two azomethine nitrogen atoms are trans to each other, while the pyrazolyl ring nitrogen atoms and the thiolato sulphurs are in cis positions. © 2002 Elsevier Science B.V. All rights reserved.

Inorganica Chimica Acta

Synthesis and structural characterisation of new iron(III) complexes with biologically relevant pyrazolyl thiosemicarbazones

New iron(III) complexes of 5-methyl-3-formylpyrazole thiosemicarbazone (HMPzTS) and 5-methyl-3-formylpyrazole-4-phenylthiosemicarbazone (HMPzPTS), namely [Fe(MPzTS)2]X and [Fe(MPzPTS)2]X respectively, where X = Cl, NO3, SCN and ClO4, have been synthesised and physico-chemically characterised by magnetic measurements (polycrystalline state), electronic, i.r., e.s.r. and Mössbauer spectra. All are cationic complexes containing two monoprotonic tridentate ligands with NNS donor sites and an anionic counterpart; they behave as 1:1 electrolytes in MeOH/DMF. Coordination to central iron(III) via the pyrazolyl nitrogen (2N), the azomethine nitrogen and the thiolato sulphur atom is confirmed in the complexes from i.r. data. E.s.r. data (RT &amp; LNT) reveal the presence of a spin-paired iron(III) cation with d2xyd2yzd1xy configuration. The 57Fe Mössbauer spectral data (RT) are commensurate with the presence of two iron(III) spin states, the percentage of each being dependent upon the counterion of the species.

New iron(III) complexes with thiosemicarbazones derived from 5-methyl-3-formylpyrazole

The reaction of CuCl2,2H2O with S-benzyl-β-N-(5-methyl pyrazole - 3 - yl) methylene dithiocarbazide (H2L) in dry ethanol affords a novel copper(II) complex [Cu(LOEt)Cl] (1) in which a unique transformation at the carbon site of the azomethine function of the parent ligand (H2L) occurs and is ascertained by X-ray crystallographic data.

Chemistry Letters

Synthesis, spectral and structural characterisation of chloro{S-benzyl-Î²-N-(5-methylpyrazole-3-yl)ethoxymethylenedithiocarbazato} copper(II) derived from S-benzyl-Î²-N-(5-methylpyrazole-3-yl)methylenedithiocarbazide

The coordination mode of the title ligand, HMPzSB (synthesized for the first time and characterised by elemental analysis, mass, IR and PMR spectral parameters), is reported by solid state isolation and physicochemical identification of cobalt(III) complexes, [Co(MPzSB)2]X (X = Cl, ClO4 and BF4). Electronic spectral features of these diamagnetic CoIII species classify them as six-coordinate distorted octahedral ones. IR spectra (4000-200 cm-1) of HMPzSB and its complexes are indicative of an uninegative tridentate NNS function of the title ligand through the Pyrazolyl (2N) nitrogen, azomethine nitrogen and thiolato sulphur atom. 1H-NMR data (in d6-DMSO at 300 MHz) of the uncomplexed ligand and its CoIII species are commensurate with the tridenticity (NNS) of the deprotonated form of HMPzSB. X-ray crystallographic studies of [Co(MPzSB)2]Cl has authenticated that the geometry of the species is distorted octahedral, as envisaged, with the two deprotonated primary ligand systems (MPzSB-). The Co - N (azomethine) and Co - N (pyrazolyl) bond lengths are 1.898(4) &amp; 1.954(5) Å and 1.903(4) &amp; 1.916(5) Å in ligand A &amp; B, respectively where as that of Co - S (thiolato) is 2.217(2) and 2.255(2) Å in the two ligands. The extended planarity of the dithiocarbazate moiety and the pyrazolyl ring of the primary ligand system are maintained because of the ligation phenomenon to CoIII. © 1997 Elsevier Science Ltd.

Synthesis and spectroscopic characterisation of cobalt(III) complexes with S-benzyl dithiocarbazate of 5-methyl-3-formyl pyrazole (HMPzSB) : X-ray crystal structure of [Co(MPzSB)2]Cl

Synthesis, spectroscopy and cyclic voltammetry of cobalt(III) complexes with 5-methyl-3-formylpyrazole N(4)-cyclohexylthiosemicarbazone (HMPz4Cy): X-ray crystal structure of [Co(MPz4Cy)2]ClÂ·2.75H2O

Journal	Transition Metal Chemistry
Publisher	-
ISSN	0340-4285