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Inorg. Chem. 2000, 39, 3042-3048
Structurally Diverse Copper(II)-Carboxylato Complexes: Neutral and Ionic Mononuclear Structures and a Novel Binuclear Structure George Psomas,† Catherine P. Raptopoulou,‡ Lykourgos Iordanidis,§ Catherine Dendrinou-Samara,† Vassilis Tangoulis,‡ and Dimitris P. Kessissoglou*,† Department of General and Inorganic Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54006, Greece, Institute of Materials Science, NCSR “Demokritos”, Aghia Paraskevi Attikis 15310, Greece, and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1322 ReceiVed December 22, 1999
The copper complexes with the commercial auxin herbicides MCPA, 2,4-D, and 2,4,5-T in the presence of a nitrogen donor heterocyclic ligand, phen or bipyam, were prepared and characterized. The available evidence supports a dimeric structure for the 2,4-D complex in the presence of bipyam while phen leads to monomeric forms. The EPR spectrum of Cu2(2,4-D)4(bipyam)2 at 4 K in the solid state exhibits an axial signal which corresponds to almost isolated S ) 1/2 magnetic ions. Magnetic data for the dimer show a weak antiferromagnetic interaction between the two metal ions with J ) -0.8 cm-1. The crystal structures of tetrakis[(2,4-dichlorophenoxy)acetato]bis(2,2′-bipyridylamine)dicopper(II), 1, bis(1,10-phenanthroline)[(2,4,5-trichlorophenoxy)acetato]copper(II) chloride, 2, and aqua(1,10-phenanthroline)bis[((2-methyl-4-chlorophenoxyacetato]copper(II), 3, were determined and refined by least-squares methods using three-dimensional MoKR data. 1 crystallizes in space group P1h, in a cell of dimensions a ) 10.813(1) Å, b ) 12.138(1) Å, c ) 11.909(1) Å, R ) 86.448(3)°, β ) 80.127(3)°, and γ ) 63.982(3)°, and V ) 1383.7(2) Å3, with Z ) 1. 2 crystallizes in space group I2/a, in a cell of dimensions a ) 29.958(9) Å, b ) 11.342(3) Å, c ) 21.196(7) Å, β ) 107.94(1)°, and V ) 6852.2(4) Å3, with Z ) 8. 3 crystallizes in space group P1h, in a cell of dimensions a ) 8.7419(8) Å, b ) 12.512(1) Å, c ) 14.598(1) Å, R ) 110.737(1)°, β ) 95.742(2)°, γ ) 103.286(2)°, V ) 1424.1(2) Å3, with Z ) 2.
Introduction Many binuclear Cu(II) carboxylato compounds have been isolated and their magnetostructural correlations studied.1-3 In most cases, the formula of the complexes is Cu2(OOCR)4L2 [L ) H2O, dmf (dimethylformamide), dmso (dimethyl sulfoxide), Py (pyridine)]. The presence of binuclear copper(II) carboxylates under catalytic reaction conditions has enhanced the interest in the coordination modes of this class of compounds. In general, binuclear copper(II) carboxylates exhibit a paddle-wheel cage structure, but due to the various coordination modes of the carboxylato ligand, additional interesting structures have been confirmed by X-ray crystallography (vide infra). The isolation of mononuclear carboxylato compounds has also confirmed the existence of unidentate and bidentate coordination modes of the ligands.4-7 The electrochemical behavior of binuclear complexes as one means of determining reactivity differences between binuclear and mononuclear complexes has also attracted much interest.8-14 Phenoxyalkanoic acids interact with Cu(II) ions to †
Aristotle University of Thessaloniki. NCSR “Demokritos”. Michigan State University. (1) Doedens, R. J. Prog. Inorg. Chem. 1975, 19, 173. (2) Melnik, M. Coord. Chem. ReV. 1982, 42, 259. (3) Kato, M.; Muto, Y. Coord. Chem. ReV. 1988, 92, 45. (4) Prout, C. K.; Barrow, M. J.; Rossotti, F. J. C. J. Chem. Soc. A 1971, 3326. (5) Prout, C. K.; Armstrong, R. A.; Carruthers, J. R.; Forrest, J. G.; Murray-Rust, P.; Rossotti, F. J. C. J. Chem. Soc. A 1968, 2791. (6) Davey, G.; Stephens, F. S. J. Chem. Soc. A 1971, 1917. (7) Davey, G.; Stephens, F. S. J. Chem. Soc. A 1971, 2577. (8) Gisselbrecht, J. P.; Gross, M.; Alberts, A. H.; Lehn, J. M. Inorg. Chem. 1980, 19, 1386. ‡ §
form complexes which have been shown to have diverse stereochemistries.15-21 We have initiated studies on the coordination of herbicide and/or antiinflammatory carboxylate agents with Cu(II) and d10 ions in an attempt to examine their mode of binding and possible synergetic effects.22-29 In this paper, we report the solid and solution behavior of mononuclear and binuclear Cu(II) com(9) Lintvedt, R. L.; Schoenfelner, B. A.; Rupp, K. A. Inorg. Chem. 1986, 25, 688. (10) Zehetmair, J. K.; Lintvedt, R. L. Inorg. Chem. 1990, 29, 2201. (11) Long, R. C.; Hendrickson, D. N. J. Am. Chem. Soc. 1983, 105, 1513. (12) Bradbury, R.; Hampton, J. L.; Martone, D. P.; Maverick, A. W. Inorg. Chem. 1989, 28, 2392. (13) Doine, H.; Stephens, F. F.; Cannon, R. D. Inorg. Chim. Acta 1983, 75, 155. (14) Cabral, M. F.; De O. Cabral, J.; Van Rijn, J.; Reedijk, J. Inorg. Chim. Acta 1984, 87, 87. (15) Smith, G.; O’Reilly, E. J.; Kennard, C. H. L.; Stadnicka, K.; Oleskyn, B. Inorg. Chim. Acta 1981, 47, 111. (16) Smith, G.; O’Reilly, E. J.; Kennard, C. H. L. J. Chem. Soc., Dalton Trans. 1981, 2462. (17) Smith, G.; O’Reilly, E. J.; Kennard, C. H. L. Inorg. Chim. Acta 1981, 49, 53. (18) Smith, G.; O’Reilly, E. J.; Kennard, C. H. L.; Brown, K. E. Inorg. Chim. Acta 1981, 52, 55. (19) Smith, G.; O’Reilly, E. J.; Kennard, C. H. L.; Stadnicka, K.; Oleskyn, B. Inorg. Chim. Acta 1982, 59, 241. (20) Smith, G.; O’Reilly, E. J.; Kennard, C. H. L. Inorg. Chim. Acta 1981, 62, 241. (21) Smith, G.; O’Reilly, E. J.; Kennard, C. H. L.; Mak, T. C. W. Inorg. Chim. Acta 1982, 65, L219. (22) Dendrinou-Samara, C.; Kessissoglou, D. P.; Manoussakis, G. E.; Mentzafos, D.; Terzis, A. J. Chem. Soc., Dalton Trans. 1990, 959. (23) Dendrinou-Samara, C.; Jannakoudakis, P. D.; Kessissoglou, D. P.; Manoussakis, G. E.; Mentzafos, D.; Terzis, A. J. Chem. Soc., Dalton Trans. 1992, 3259.
10.1021/ic991476q CCC: $19.00 © 2000 American Chemical Society Published on Web 06/13/2000
Copper(II)-Carboxylato Complexes Chart 1
plexes with the commercial auxin herbicides MCPA, 2,4-D, and 2,4,5-T (Chart 1) in the presence of phen or bipyam. A biological study of a series of copper complexes with herbicide ligands will be presented in a following paper.29b We also report the molecular and the crystal structures of tetrakis[(2,4-dichlorophenoxy)acetato]bis(2,2′-bipyridylamine)dicopper(II), 1 the first example of a binuclear structure with two bridging and two unidentate carboxylato ligands, [bis(1,10phenanthroline)[(2,4,5-trichlorophenoxy)acetato]copper(II) chloride, 2, and aqua(1,10-phenanthroline)bis[(2-methyl-4-chlorophenoxy)acetato]copper(II), 3. Experimental Section Materials. The chemicals for the syntheses of the compounds were used as purchased. Acetonitrile (CH3CN) was distilled from calcium hydride (CaH2) and CH3OH from magnesium (Mg), and both were stored over 3 Å molecular sieves. Diethyl ether, anhydrous grade, and absolute ethanol were used without any further purification. 2,4-D, 2,4,5-T, MCPA, phen, bipyam, and CuCl2‚2H2O were purchased from Aldrich. All chemicals and solvents were of reagent grade. Physical Measurements. Infrared spectra (200-4000 cm-1) were recorded on a Perkin-Elmer FT-IR 1650 spectrometer with samples prepared as KBr pellets, and UV-vis spectra were recorded on a Shimadzu 160A dual-beam spectrophotometer. Room-temperature magnetic measurements were carried out by Faraday’s method using mercury tetrathiocyanatocobaltate(II) as a calibrant. Variable-temperature magnetic susceptibility measurements were carried out on powdered samples in the 3-300 K temperature range using a Quantum Design SQUID susceptometer in a 6.0 kG applied magnetic field. Magnetization measurements were performed at 4 K and in the field range 0-5 T. EPR spectra were recorded on a Bruker ER 200D-SRC X-band spectrometer equipped with an Oxford ESR 9 cryostat. C, H, and N elemental analyses were performed on a Perkin-Elmer 240B elemental analyzer; Cu was determined by atomic absorption spectroscopy on a Perkin-Elmer 1100B spectrophotometer. Electric conductance measurements were carried out with a WTW model LF 530 conductivity outfit and a type C cell, which had a cell constant of 0.996. This represents a mean value calibrated at 25 °C with potassium chloride. All temperatures were controlled with an accuracy of (0.1 °C using a Haake thermoelectric circulating system. (24) Kessissoglou, D. P.; Manoussakis, G. E.; Hatzidimitriou, A. G.; Kanatzidis, M. G. Inorg. Chem. 1987, 26, 1395. (25) Hatzidimitriou, A. G.; Kessissoglou, D. P.; Manoussakis, G. E.; Kourounakis, P. N.; Economidis, G. J. Inorg. Biochem. 1990, 39, 263. (26) Hatzidimitriou, A. G.; Kessissoglou, D. P.; Manoussakis, G. E. J. Inorg. Biochem. 1993, 47, 157. (27) Dendrinou-Samara, C.; Psomas, G.; Christophorou, K.; Tangoulis, V.; Raptopoulou, C. P.; Terzis, A.; Kessissoglou, D. P. J. Chem. Soc., Dalton Trans. 1996, 3737. (28) Psomas, G.; Dendrinou-Samara, C.; Philippakopoulos, P.; Tangoulis, V.; Raptopoulou, C. P.; Samaras, H.; Kessissoglou, D. P. Inorg. Chim. Acta 1998, 272, 24. (29) (a) Dendrinou-Samara, C.; Tsotsou, G.; Raptopoulou, C. P.; Kortsaris, A.; Kyriakidis, D.; Kessissoglou, D. P. J. Inorg. Biochem. 1998, 71, 171. (b) Dendrinou-Samara, C.; Psomas, G.; Raptopoulou, C. P.; Kessissoglou, D. P. J. Inorg. Biochem. to be submitted for publication.
Inorganic Chemistry, Vol. 39, No. 14, 2000 3043 Preparation of the Ligands. The sodium salts of the ligands were prepared by the reaction of the protonated ligand with NaOH or CH3ONa in methanol. The white solids were recrystallized from methanol and dried in the air. Synthesis of Tetrakis[(2,4-dichlorophenoxy)acetato]bis(2,2′-bipyridylamine)dicopper(II), 1. 2,4-D (2.21 g, 10 mmol) was dissolved in CH3OH (50 cm3), and CH3ONa (0.54 g, 10 mmol) was added. After 30 min of stirring, CuCl2‚2H2O (0.85 g, 5 mmol) and bipyam (1.71 g, 10 mmol) in CH3OH (25 cm3) were added dropwise. The reaction mixture was refluxed for 1 h. The blue solution was reduced in volume and left for slow evaporation. Crystals of Cu2(C6H3Cl2-OCH2COO)4(bipyam)2, 1, suitable for X-ray structure determination deposited over 1 week. Yield: 70%. Anal. Calcd for C52H38Cl8N6O12Cu2 (fw ) 1349.62): C, 46.28; H, 2.84; N, 6.23; Cu, 9.42. Found: C, 46.50; H, 3.00; N, 6.10; Cu, 9.50. IR, (KBr pellet), νmax/cm-1; ν(N-H) 3275 (m), 3230 (m); νas(CO2) 1635, 1585 (vs); ν(CdN) 1470 (vs), 1435 (vs); νsym(CO2) 1395 (vs). UV-vis (dmf solution), λ/nm (/dm3 mol-1 cm-1); 735 (111), 400 (162), 314 (16 600). Synthesis of Bis(1,10-phenanthroline)[(2,4,5-trichlorophenoxy)acetato]copper(II) Chloride, 2. 2,4,5-T (2.555 g, 10 mmol) was dissolved in CH3OH (50 cm3), and CH3ONa (0.54 g, 10 mmol) was added. After 30 min of stirring, CuCl2‚2H2O (0.85 g, 5 mmol) and phen (1.80 g, 10 mmol) in CH3OH (25 cm3) were added dropwise. The reaction mixture was refluxed for 1 h. The blue solution was reduced in volume and left for slow evaporation. Crystals of [Cu(C6H2Cl3OCH2COO)(phen)2]Cl, 2, suitable for X-ray structure determination were deposited over 1 week. Yield: 65%. Anal. Calcd for C31H37Cl4N4O8Cu (fw ) 799.01): C, 46.60; H, 4.67; N, 7.01; Cu, 7.95). Found: C, 46.90; H, 4.25; N, 7.35; Cu, 8.10. IR (KBr, pellet), νmax/ cm-1: νas(CO2) 1620, 1585 (vs); ν(CdN) 1465(vs), 1430(vs); νsym(CO2) 1395 (vs). UV-vis (dmf solution), λ/nm (/dm3 mol-1 cm-1): 957 (63), 723 (100), 328 (2450), 293 (20 240). Synthesis of Aqua(1,10-phenanthroline)bis[(2-methyl-4-chlorophenoxy)acetato]copper(II), 3. MCPA (2.00 g, 10 mmol) was dissolved in CH3OH (50 cm3) and CH3ONa (0.54 g, 10 mmol) was added. After 30 min of stirring, CuCl2‚2H2O (0.85 g, 5 mmol) in CH3OH (25 cm3) was added dropwise. The reaction mixture was stirred for 1 h and reduced in volume under vacuum. Microcrystalline Cu[C6H3(CH3)ClOCH2COO]2(H2O)2 deposited and was collected by filtration. Cu[C6H3(CH3)ClOCH2COO]2(H2O)2 (3 mmol) was dissolved in CH3CN (50 cm3), phen (0.54 g, 3 mmol) in CH3CN (25 cm3) was added, and the mixture was stirred for 1 h and left for slow evaporation. Crystals of Cu[C6H3(CH3)ClOCH2COO]2(phen)(H2O), 3, suitable for X-ray structure determination deposited over 1 week. Yield: 60%. Anal. Calcd for C30H26Cl2N2O7Cu (fw ) 660.97): C, 54.51; H, 3.97; N, 4.24; Cu, 9.61. Found: C, 54.40; H, 3.90; N, 4.45; Cu, 9.50. IR (KBr pellet), νmax/cm-1: νas(CO2) 1630 (vs), 1605 (vs); ν(CdN) 1490 (vs), 1430 (vs); νsym(CO2) 1408 (vs). UV-vis (dmf solution), λ/nm (/dm3 mol-1 cm-1): 675 (94). X-ray Crystal Structure Determinations. A green prismatic crystal of tetrakis[(2,4-dichlorophenoxy)acetato]bis(2,2′-bipyridylamine)dicopper(II), 1, with approximate dimensions 0.15 × 0.30 × 0.60 mm, and a blue crystal of bis(1,10-phenanthroline)[(2,4,5-trichlorophenoxy)acetato]copper(II) chloride, 2, with approximate dimensions 0.10 × 0.25 × 0.55 mm, were mounted in air. Diffraction measurements were made on a Nicolet P21 diffractometer upgraded by Crystal Logic using Ni-filtered Cu radiation for 1 and on a Crystal Logic dual-goniometer diffractometer using graphite-monochromated Mo radiation for 2. A pale blue prismatic crystal of aqua(1,10-phenanthroline)bis[2-methyl4-chlorophenoxy)acetato]copper(II), 3 with dimensions 0.77 × 0.16 × 0.16 mm, was mounted on the top of a glass fiber, and data were collected at room temperature with a Bruker SMART Platform CCD diffractometer. A full sphere of data (2082 frames) were collected. Final cell constants were calculated from a set of 6770 strong reflections (I > 10σ(I)) obtained from the data collection. Crystal data and parameters for the data collections of 1-3 are reported in Table 1. Unit cell dimensions were determined and refined by using the angular settings of 25 automatically centered reflections in the ranges 24° < 2 θ < 54° for 1 and 11° < 2 θ < 23° for 2. Intensity data were recorded using θ-2θ scans. Three standard reflections, monitored every 97 reflections, showed
