КООРДИНАЦИОННАЯ ХИМИЯ, 2007, том 33, № 11, с. 858-863
УДК 541.49
DIOXOMOLYBDENUM(VI) COMPLEXES OF 2-HYDROXYBENZALDEHYDE 4-PHENYL-S-METHYLTHIOSEMICARBAZONE
© 2007 Y. D. Kurt*, G. S. Pozan **, I. KkiIciMi*, B. Ülküseven*
*Istanbul University, Chemistry Department, Avcilar, 34320, Istanbul, Turkey ** Istanbul University, Chemical Engineering Department, Avcilar, 34320, Istanbul, Turkey
Received June 25, 2006
Mixed ligand complexes of dioxomolybdenum(VI) with 2-hydroxybenzaldehyde 4-phenyl-S-methylthiosemi-carbazone (H2L) were prepared with the formula [MoO2(L)D] (D = H2O; methyl, «-butyl, and n-undecyl alcohol; DMF, DMSO, pyridine, 4-picoline, and 3,5-lutidine). The compounds were characterized by elemental analysis, IR and NMR spectroscopy. The thermal decomposition of the compounds were investigated by using TGA, DTG, and DTA methods in air, and the thermal behavior depending on the second ligand molecule was discussed. A single crystal of the DMF coordinated complex was studied by X-ray diffractometry.
Thiosemicarbazones have been of great importance because of their biological activity. In recent years, many papers were published about structural properties and biological activity of metal complexes of thiosemi-carbazone derivatives [1-7]. However, studies of the thiosemicarbazone complexes with molybdenum as oligoelement are in a relatively little number, and sol-vated molybdenum(VI) complexes of thiosemicarbazones, which are a special class of molybdenum chelates, are very limited [8-12]. Various molybdenum complexes are essential in enzymes such as nitrogena-se, sulfite, and xanthine oxidases [13, 14], and even some of the molybdenum compounds are included in excellent enzyme model systems [15, 16]. In addition, it is known that some molybdenum compounds catalyze the oxygen atom transfer mechanisms [17, 18].
The purpose of this study is to synthesize, characterize, and investigate thermal behavior of nine new molybdenum complexes of 2-hydroxybenzaldehyde 4-phenyl-S-methylthiosemicarbazone (H2L) (Fig. 1). The complexes, [MoO2(L)D] (I-IX) (D = H2O (I), methyl (II), «-butyl(III), and «-undecyl alcohol (IV), DMF (v), DMSO (VI), pyridine (VII), picoline (VIII), or lutidine (IX)), and the complex [MoO2(L)] (X) were isolated as reference compounds. The compounds were characterized by elemental analyses, IR and *H NMR spectra. The thermoanalytical data were obtained using TGA, DTG, and DTA measurements. The structure of [MoO2(L)DMF] (V) was also investigated using single crystal X-ray diffraction method.
EXPERIMENTAL
Chemicals, apparatus, and data collection. All
chemicals and solvents were of reagent grade. IR spectra were recorded on a Mattson 1000 FT-IR spectrometer. Analytical data were obtained with a Thermo Finnigan
Flash EA 1112 analyzer. 1H NMR spectra were obtained on a Varian INOVA 500 MHz spectrometer .
X-ray measurements were made on a Rigaku RAXIS RAPID imaging plate area detector with graphite monochromated Mo^a radiation. The data were corrected for Lorentz and polarization effects. An empirical absorption correction was applied which resulted in transmission factors ranging from 0.79 to 1.00. The molecular and crystal structures were solved by direct methods implemented in the SIR92 program [19]. Hydrogen atoms were refined using the riding model, and the non-hydrogen atoms were refined anisotropically. All calculations were performed using the Crystal Structure [20, 21] crystallographic software package.
Fig. 1. ORTEP drawing of [MoO2(L)DMF] (V).
Thermal degradation experiments were carried out on a Shimadzu TGA-50 Thermogravimetric Analyzer. A constant heating rate of 10 K/min was used between room temperature and 800°C. The air flow rate was 50 ml/min for thermooxidative degradation runs. Sample weights were 16-18 mg in all cases. Differential thermal analyses were determined by Linseis L62 differential thermal analyser. The samples were heated up to 900°C with a heating rate of 10 K/min in air.
Synthesis. 2-hydroxybenzaldehyde 4-phenyl-iS-me-thylthiosemicarbazone (H2L), [MoO2(Acac)2], and [MoO2(L)] (X) were prepared with small modifications of general methods [22, 23]. Synthesis procedures of the compounds I-X are given below.
Compound [MoO2(L)H2O] (I): MoO2(Acac)2 (0.44 g, 1.40 mmol) and of H2L (0.4 g, 1.40 mmol) were dissolved in CHCl3 (10 ml) and the mixture was refluxed for 1 h. After this period, 2 ml of H2O were then added with stirring to the warm reaction mixture. The final suspension was stirred for 4 h and kept for 12 h at room temperature. The orange precipitate was collected by filtration and washed twice with 2-4 ml of CHCl3. The product was dried for 12 h in air.
[MoO2(L)MeOH] (II). A mixture of MoO2(Acac)2 (0.44 g, 1.40 mmol) and thiosemicarbazone H2L (0.4 g, 1.40 mmol) in 10 ml MeOH was prepared, and then the solution was refluxed for 1 h. The orange precipitate was filtered off and washed with 2 ml of MeOH and a small amount of CHCl3. The product was dried for 12 h in air.
Complexes III-VI were synthesized in «-butyl alcohol, «-undecyl alcohol, DMF and DMSO in a similar manner.
[MoO2(L)Py] (VII). A mixture of MoO2(Acac)2 (0.44 g, 1.40 mmol) and the ligand H2L (0.4 g, 1.40 mmol) in 10 ml MeOH was prepared. To the solution, 5 ml of pyridine was added dropwise with stirring at room temperature. After the reaction mixture was refluxed for 2 h, the suspension was stirred slowly for 12 h at room temperature. The orange-red precipitate was filtered off and washed with MeOH-CHCl3 (1 : 5, 2 ml) and CHCl3 (5 ml), respectively. The final product was dried for 12 h in air.
Complexes VIII and IX were synthesized by using similar procedures.
FT-IR (v, cm-1) and *H NMR (500 MHz, 25°C, 5 ppm, J, Hz) data of the I-IX complexes: the solvent (D), color, mp(°C), yield(%), found/calcd analytical data were given as follows.
(I) C15H15N3O4SMo: H2O, orange, 227.5, 38, C 42.03 (41.97); H 3.48 (3.52); N 9.64 (9.79), IR: 1438 5(OH), XH NMR(CDCl3): 3.40 s. (broad, 3H, H2O).
(II) C16H17N3O4SMo: MeOH, orange, 229.0, 52, C 43.20 (43.35); H 3.69 (3.87); N 9.53 (9.48), IR: 3414 v(OH), 2929 v(CH), 1496 5(CH3), 1367 5(CH2), xH NMR (CDCl3,): 4.48 s. (1H, OH), 3.50 s. (3H, CH3).
(III) C19H23N3O4SMo: BuOH, orange, 223.4, 48, C 47.15 (47.01); H, 4.61 (4.78); N 8.75 (8.66), IR: 3435 v(OH), 2966 v(CH), 1464 5(CH3), 1366 6(CH2); 1H NMR (DMSO-dg): 4.29 d-d (J = 5.38, J = 4.88, 1H, OH), 3.28 q. (J = 4.88 and 5.37, 2H, C1H2), 1.37-1.41 m. (J = 5.376.35, 2H, C2H2), 1.28-1.32 m. (J = 5.35-6.35, 2H, C3H2), 0.86 unsplitted d-d (J = 7.33 and 6.83, 3H, C4H3).
(IV) C26H37N3O4SMo: «-Undecyl alcohol, orange, 130.0-131.5, 46, C 53.59 (53.51); H 6.52 (6.39); N 7.35 (7.20), IR: 3403 v(OH), 2929 and 2856 v(CH), 1474 5(CH3), 1362 6(CH2), XH NMR (DMSO-d6): 4.27 d-d (J = 5.37, J = 6.88, 1H, OH), 3.37 m. (J = 4.88, J = 5.37, J = 6.35, 2H, C*H2), 2.51 m. (4H, C2 3H2), 2.49 unsplitted m. (4H, C4 5H2), 1.40 unsplitted m. (2H, C6H2), 1.25-1.28 unsplitted m. (8H, C7-10H2), 5 = 0.86 t. (J = 6.82, 3H, CnH3).
(V) C18H20N4O4SMo: DMF, red, 191.5, 44, C 44.43 (44.63); H 4.34 (4.16); N 11.48 (11.57), IR: 1662 v(C=O), 1480 5(CH3), XH NMR (CDCl3): 2.55 s. (6H, -(CH3)2).
(VI) C17H19N3O4S2Mo: DMSO, red, 202.0, 93, C 41.60 (41.72); H 4.14 (3.91); N 8.10 (8.59), IR: 1480 5(CH3), 1007 v(S=O), *H NMR (DMSO-d6): 7.96 s. (1H, NH), 2.83 s. (1H, CH3), 2.73 s. (1H, CH3).
(VII) C20H18N4O3SMo: Pyridine, orange-red, 221.0-222.0, 32, C 44.63 (48.98); H 3.62 (3.70); N 10.41 (11.43), IR: not sorted, *H NMR (DMSO-d6) 8.58 t. (J = 5.35, 1H, H2), 7.79 d. (J = 5.39, 1H, H6), 7.40-7.36 q. and doublets (J = 5.38, 3H, H35).
(VIII) C21H20N4O3SMo: 4-Picoline, orange, 209.3-209.9, 34, C 49.97 (50.00); H 4.06 (4.00); N 10.97 (11.11), IR: 1445 5(CH3), XH NMR (DMSO-d6): 8.42 d. (J = 5.50, 2H, H26), 7.34-7.38 d. (J = 5.42, 2H, H35), 2.32 s. (3H, CH3).
(IX) C22H22N4O3SMo: 3,5-Lutidine, orange, 208.9, 63, C 50.91 (50.97); H 4.34 (4.28); N 10.72 (10.81), IR: 1440 5(CH3), XH NMR (DMSO-d6): 8.21 broad s. (2H, H26), 7.41 broad s. (1H, H4), 2.25 s. (6H, (CH3)2).
(X) C15H12N3O4SMo: solvent-free, orange, 227.5-228.0, 35, C 42.48 (42.25); H 2.92 (2.81); N 9.72 (9.86).
RESULTS AND DISCUSSION
Some physical properties of complexes. In the selected D solvent the interaction between the ligand (H2L) and MoO2(Acac)2 in 1 : 1 molar ratio yielded stable solid complexes corresponding to the general formula [MoO2(L)D] (D = H2O, methyl, «-butyl, and «-undecyl alcohol; DMF, DMSO, pyridine, 4-picoline, and 3,5-lutidine).
The typical formation reaction is given below: MoO2( Acac) 2 + H2L + D —-—[ MoO2 (L) D ] + 2AcacH.
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Table 1. Crystal data and structure refinement parameters for [MoO2(L)DMF] (V)
Empirical formula C18H20N4O4SMo
Formula weight 484.38
Crystal color, habitus Red, block
Wavelength of Mo^a radiation, A 0.71070
Crystal dimensions, mm 0.60 x 0.40 x 0.20
Crystal system Monoclinic
Space group P21/n (#14)
Lattice type Primitive
a, A 13.1803(11)
b, A 8.7834(9)
c, A 18.720(2)
a, p, deg 90.00, 109.8700(11)
Z; V, A3; pcalc, g cm-3 4; 2038.2(3); 1.578
^000 984
T, K 293 ± 1
^(Motfo,), cm-1 7.76
Refl. collected/unique 65809/6960
Rint 0.030
Data I > 2.00 o(I)/parameters 6153/273
R 0.037
Rw 0.017
Goodness- of fit-indicator 1.273
Max/min peak in final diff. map, eA-3 0.50/-0.65
The molybdenum compounds were formed as crystalline powder or a mixture of amorphous and crystalline materails. However, one of these structures, [MoO2(L)DMF] (V), could be obtained as a suitable single crystal for X-ray study. The diamagnetic complexes were insoluble in water but soluble in ethanol, acetone, and polar organic solvents.
IR spectra. Were obtained as KBr disc in the 4000400 cm-1 range. The v(C=Nx) and (N4=C) vibrations of S-methylthiosemicarbazone and the dioxomolybdenum complexes were monitored at 1620-570 cm-1. The phenolic (C-O) band of H2L at 1547 cm-1 shifts to the 15571551 cm-1 range in the spectra of the complexes because of coordinat
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