IR analysis of the carboxylate forms in structurally determined [CuII(κ3-L)2] species isolated from different acidic solutions

Bojan Kozlevčar, Marta Počkaj, Nives Kitanovski

Abstract


Several copper(II) coordination compounds with the tridentate κ3-N,N,O bisligand (L = bis(3,5-dimethylpyrazol-1-yl)acetate or its molecular acid form HL = Hbdmpza) were synthesized from different starting metal salts in appropriate acidic water solutions as reported. The XRD single crystal structural analysis reveals neutral acidic ligand form in [Cu(HL)2]·2(HSO4) (1) and [Cu(HL)2]·2Cl (2), while ionic in [Cu(L)2]·(CH3COOH)·(H2O) (3), and [Cu(L)2]·2(H2O) (4). The molecular structures of 2 and 3 are first reported herein, thus enabling a clearer insight for the IR - structural analysis. Two carboxylate C-O bond lengths ranges, namely differing 1.29/1.22 Ǻ for 2, and the same 1.24/1.24 Ǻ for 3, respectively, are in agreement with the single(longer)/double(shorter) character of both bonds for the neutral carboxylic  HL in 2, and the same character of both bonds for the carboxylate anionic L- in 3, as seen for the related 1 (HL) and 4 (L-). The most distinguished IR spectra difference for the molecular (HL) / ionic (L-) is at the 1700 cm-1 carboxylate band. The C=O free ligand (HL) double bond position at 1740 cm-1 is most similar with 1702 cm-1 in 1, while a split band at 1697, 1665 cm-1 is seen for 2. On the other hand, the anionic asymmetric carboxylate stretching IR band (`nas(COO)) for 3 (1642 cm-1) and 4 (1635 cm-1) is found at lower energy region. Thus, the additional band within the same region, as seen only for 3 at 1716 cm-1, is assigned to the network neutral acetic acid C=O double bond.

Keywords


Hbdmpza; copper; IR; structure; carboxylate

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References


J. D. Lee, Concise Inorganic Chemistry. 5. ed., Chapman & Hall, London, 1996, 653–678.

A. K. Brisdon, Inorganic Spectroscopic Methods. Ox¬ford University Press, Oxford 1998.

B. N. Figgis, M. A. Hitchman, Ligand Field Theory and Its Applications. Wiley-VCH, New York, 2000.

G. Socrates, Infrared Characteristic Group Frequencies. 2. ed., John Willey & Sons, Chicester, 1998.

K. Nakamoto, Infrared and Raman Spectra of Inorganic and Coordination Compounds, Parts A and B,. John Wiley & Sons, New York, 1997.

Y. Mathey, D. R. Greig, D. F. Shriver, Variable-temperature Raman and infrared spectra of the copper acetate dimer Cu2(O2CCH3)4(H2O)2 and its derivatives, Inorg. Chem., 21, 3409–3413 (1982).

J. N. van Niekerk, F. R. L. Schoening, A new type of copper complex as found in the crystal structure of cupric acetate, Cu2(CH3COO)4.2H2O, Acta Crystallogr., 6, 227–232 (1953).

S. Trofimenko, Scorpionates, The Coordination Chemistry of Polypyrazolylborate Ligands, Imperial College Press, London, 2005.

C. Pettinari, R. Pettinari, Metal derivatives of poly (pyrazolyl) alkanes: II. Bis (pyrazolyl) alkanes and related systems, Coord. Chem. Rev., 249, 663–691 (2005).

N. Burzlaff, Tripodal N, N, O-ligands for metalloen¬zyme models and organometallics, in Advances in Inorganic Chemistry, 60, 101–165 (2008).

B. Kozlevčar, P. Gamez, R. de Gelder, W. L. Driessen, J. Reedijk, Unprecedented Change of the Jahn-Teller Axis in a Centrosymmetric CuII Complex Induced by Lattice Water Molecules. Crystal and Molecular Structures of Bis[bis(3,5-dimethylpyrazol-1-yl)ace¬tato]copper(II) and Its Dihydrate, Eur. J. Inorg. Chem., 47–50 (2003).

B. Kozlevčar, P. Gamez, R. de Gelder, Z. Jagličić, P. Strauch, N. Kitanovski, J. Reedijk, Counterion and Solvent Effects on the Primary Coordination Sphere of Copper(II) Bis(3,5-dimethylpyrazol-1-yl)acetic Acid Coordination Compounds, Eur. J. Inorg. Chem., 3650–3655 (2011).

A. Otero, J. Fernandez-Baeza, J. Tejeda, A. Antinolo, F. Carrillo-Hermosilla, E. Diez-Barra, A. Lara-Sanchez, M. Fernandez-Lopez, M. Lanfranchi, M. A. Pellinghelli, Syntheses and crystal structures of lithium and niobium complexes containing a new type of monoanionic “scorpionate” ligand, J. Chem. Soc., Dalton Trans., 3537-3539 (1999).

A. Beck, B. Weibert, N. Burzlaff, Monoanionic N,N,O-Scorpionate Ligands and their Iron(II) and Zinc(II) Complexes: Models for Mononuclear Active Sites of Non-Heme Iron Oxidases and Zinc Enzymes, Eur. J. Inorg. Chem., 521–527 (2001).

Oxford Diffraction, CrysAlis PRO: Diffraction data procesing program, Oxford Diffraction Ltd: Yarnton, UK, 2011.

A. Altomare, M. C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R. Spagna, SIR97: A new tool for crystal structure determination and refinement, J. Appl. Crystallogr., 32, 115–119 (1999).

G. M. Sheldrick, A set of programs for refinement of small (SM) and macromolecular (MM) crystal structures by single crystal X-ray and neutron diffraction. SHELXL2013, University of Göttingen, Germany, 2013.

A. L. Spek, Single-crystal structure validation with the program PLATON, J. Appl. Crystallogr., 36, 7–13 (2003).

G. B. Deacon, J. Phillips, Relationships between the carbon-oxygen stretching frequencies of carboxylato complexes and the type of carboxylate coordination, Coord. Chem. Rev., 33, 227–250 (1980).




DOI: http://dx.doi.org/10.20450/mjcce.2015.674

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