Versatility in the coordination behavior of a hexatopic compartmental Schiff-base ligand in the architecture of binuclear transition metal(II) complexes

Condensation of 1H-pyrazole-3,5-dicarboxylic hydrazide with 1H-indole-2,3-dione (isatin) yield the compartmental ligand, which is capable of encapsulating two transition metal ions namely CoII, NiII, CuII, and ZnII. The ligand is a binuclear hexadentate chelate with N4O2 donating sites. The pyrazole core provides the diazine fragment, which serves as an endogenous bridge between the two metal centers. In CoII and NiII complexes, the ligand is in the imidol form and the subsequent coordination through the imidol oxygen. In other complexes, the lactonic oxygen takes part in ligation. All the complexes are non-electrolytes and soluble in DMSO, DMF, and acetonitrile. Spectral and magnetic studies along with analytical data suggest octahedral geometry for the CoII and NiII complexes, whereas the CuII and ZnII complexes are assigned square pyramidal geometry. The CuII and NiII complexes show one electron redox behavior and the rest are electrochemically inactive.

[1]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[2]  V. Revankar,et al.  Transition metal complexes of pyrazole head 24-membered polyazamacrocyclic bimetal cores: synthesis, characterization, electrochemistry and spectral study , 2010 .

[3]  V. Revankar,et al.  Ligational behavior of a bidentate coumarin derivative towards CoII, NiII, and CuII: synthesis, characterization, electrochemistry, and antimicrobial studies , 2009 .

[4]  V. Revankar,et al.  Interaction of Co(II), Ni(II), Cu(II), and Zn(II) with N,N′-(aldose)2-thiocarbohydrazide: synthesis, electrochemistry, and spectral characterization , 2009 .

[5]  A. M. Khedr,et al.  Synthesis, characterization, thermal, and antimicrobial studies of binuclear metal complexes of sulfa-guanidine Schiff bases , 2009 .

[6]  W. Linert,et al.  Synthesis, spectroscopic, thermal, and biological activities on solvatochromic mixed ligand copper(II) complexes , 2009 .

[7]  B. Kharisov,et al.  Molecular design of mononuclear complexes of acyclic Schiff-base ligands , 2009 .

[8]  M. Kurup,et al.  Synthesis and spectral investigations of vanadium(IV/V) complexes derived from an ONS donor thiosemicarbazone ligand. , 2009, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[9]  T. Pruschke,et al.  Targeted self-assembly and quantum Monte Carlo magnetic study of an alternating nickel(II) 1D coordination polymer composed of highly preorganized binuclear tectons. , 2008, Dalton transactions.

[10]  V. Revankar,et al.  Ligational behavior of new mononucleating SNOO thiosemicarbazone ligands towards 3d metal(II) ions: synthesis and spectroscopic studies , 2008 .

[11]  F. Meyer,et al.  Selective benzylic C-C coupling catalyzed by a bioinspired dicopper complex. , 2008, Chemical communications.

[12]  Louise N. Dawe,et al.  Supramolecular self-assembled polynuclear complexes from tritopic, tetratopic, and pentatopic ligands: structural, magnetic and surface studies. , 2007, Inorganic chemistry.

[13]  F. Meyer,et al.  Pyrazolate-based copper(II) and nickel(II) [2 x 2] grid complexes: protonation-dependent self-assembly, structures and properties. , 2007, Dalton transactions.

[14]  M. Broda,et al.  The synthesis, structure and properties of N-acetylated derivatives of ethyl 3-amino-1H-pyrazole-4-carboxylate. , 2007, Chemical & pharmaceutical bulletin.

[15]  F. Meyer,et al.  Oligonuclear copper complexes of a bioinspired pyrazolate-bridging ligand: synthesis, structures, and equilibria in solution. , 2007, Inorganic chemistry.

[16]  V. Revankar,et al.  Spectroscopic studies of bridged binuclear complexes of Co(II), Ni(II), Cu(II) and Zn(II) , 2007 .

[17]  A. M. Ferreira,et al.  Oxindoles and copper complexes with oxindole-derivatives as potential pharmacological agents , 2006 .

[18]  B. Bosnich,et al.  Principles of mononucleating and binucleating ligand design. , 2004, Chemical reviews.

[19]  V. Revankar,et al.  Bimetallic complexes of a potentially pentadentate, acyclic, symmetrical compartmental Schiff base ligand that provides suitable topology for an exogenous bridge , 2002 .

[20]  V. Revankar,et al.  Symmetric binuclear complexes with an ‘end-off’ compartmental Schiff base ligand , 2002 .

[21]  C. Incarvito,et al.  Bimetallic reactivity. On the use of oxadiazoles as binucleating ligands. , 2001, Inorganic chemistry.

[22]  Â. Pinto,et al.  The chemistry of isatins: a review from 1975 to 1999 , 2001 .

[23]  V. Revankar,et al.  Oxomolybdenum(VI) and (V) complexes with 6–methyl-4–hydroxypyrimidinyl hydrazones , 1998 .

[24]  M. G. R. Reddy,et al.  A Study of Formation and Stability of Metal-Isatin Complexes in Solution , 1994 .

[25]  Edward I. Solomon,et al.  ELECTRONIC STRUCTURES OF ACTIVE SITES IN COPPER PROTEINS : CONTRIBUTIONS TO REACTIVITY , 1992 .

[26]  M. C. Feiters,et al.  X-Ray Absorption Spectroscopic Studies of Metal Coordination in Zinc and Copper Proteins , 1990 .

[27]  D. Richardson,et al.  Mixed-valence molecules: Electronic delocalization and stabilization , 1984 .

[28]  J. Knight,et al.  Identification of ampicillin, amoxicillin, and gentamicin in amino acid chromatograms. , 1982, Clinical chemistry.

[29]  W. Geary.  The use of conductivity measurements in organic solvents for the characterisation of coordination compounds , 1971 .

[30]  Stuart A. Rice,et al.  Inorganic Electronic Spectroscopy , 1968 .

[31]  D. S. Polcyn,et al.  Multistep Charge Transfers in Stationary Electrode Polarography. , 1966 .

[32]  F. Fairbrother,et al.  Book reviewA text-book of quantitative inorganic analysis: A. I. Vogel: (including elementary instrumental analysis). 3rd Ed. Longmans, Green, London, 1962. Pp.xxx + 1216 70s. , 1963 .

[33]  H. Bode,et al.  A Text‐Book of Quantitative Inorganic Analysis incl. Elementary Instrumental Analysis, von A. I. Vogel. Longmans, Green and Co., Ltd., London 1961. 3. Aufl., XXX, 1216 S., zahlr. Abb. und Tab., geb. 70 s , 1962 .

[34]  I. Kolthoff,et al.  Textbook of quantitative inorganic analysis , 1948 .