Synthesis and Characterization of 2-Butoxyethylxanthate Complexes with Iron(II), Cobalt(II), Nickel(II), Copper(II) and Zinc(II) and their Adducts with Nitrogen Base Ligands

New complexes and adducts of xanthate of the general formula [M(2-BuoEtxant)2] and [M(2-BuoEtxant)2.nL] Where M= Fe(ΙΙ), Co(ΙΙ), Ni(ΙΙ), Cu(ΙΙ) and Zn(ΙΙ), and (2-BuoEtxant)=2-Butoxyethylxanthate, and n=2 when L= pyridine; Isoquinoline, γ-picoline, 3,5-lutidine, n=1 when L= ethylenediamine, (1,10)-phenanthroline, have been prepared and characterized by metal analyses, infrared, conductance measurements, electronic absorption spectra and susceptibility measurements. Magnetic moment and electronic spectra, indicate that the complexes of type [M(2-BuoEtxant)2] are of tetrahedral geometry while the complexes of type [M(2-BuoEtxant)2.nL] have an octahedral geometry.


INTRODUCTION
Transition matel complexes in which a 1,1-dithio ligand form a four membered ring with the metal ion have been extensively investigated and thoroughly reviewed (Coucouvanis, 1979;Bond and Martin,1984;Cox, et al.,1997;Therm,1994). The four membered ring metal complexes expand their coordination number by interaction with a lewis base. This may take place by adduct formation with other ligands of comparable ligating ability. The resulting complex is significantly different from those of the complex not having the expanded coordination number (Magnus et al., 1994;Coucouvanis, 1979).

Materials and Methods
All reagents and solvents were of analytical grade and used as supplied from Fluka or BDH chemical companies. Infrared spectra were recorded on a Brucker Tensor 27co. FTIR spectrophotometer in the 400-4000 cm -1 range using KBr discs. Conductivity measurements were carried out on a 10 -3 M solution of the complexes in DMF using conductivity meter PCM3 Jenway at ambient temperature. The electronic spectra were recorded on a Shimadzu UV-visible spectrophotometer UV-160 for 10 -3 M solution of complexes in DMF as solvent at 25°C using 1cm quartz cells. Metals content was determined using AA670 atomic absorption. Melting points were recorded on an Electrothermal 9300 apparatus and were uncorrected. The magnetic measurement was carried out at 25°C on the solids by Faraday's method using Brucker BM6 instrument.

Synthesis of potassium 2-Butoxyethylxanthate
2-Butoxyethanol (11.80g, 0.10 mol) was added to aqueous solution (5.61g , 0.10mol) of potassium hydroxide with stirring. The mixture was cooled in an ice bath, to this mixture (7.60cm 3 , 0.10mol) of carbon disulfide was added dropwise with continuous stirring for 30 min. in ice bath, the yellow precipitate formed was filtered off, washed with diethylether and dried under vacuum.

RESULTS AND DISCUSSTION
The new ligand was prepared by the reaction of 2-butoxyethanol with potassium hydroxide and carbon disulphide: the complexes were prepared through direct reaction of the metal chlorides, FeCl 2 .4H 2 O, CoCl 2 .6H 2 O, NiCl 2 .6H 2 O, CuCl 2 . 2H 2 O or unhydrous ZnCl 2 with the above ligand in (1:2) molar ratio. The values of conductivity measurement in dimethylformamide solution of the complexes are in the range (2.30-38.30) Ω -1 .cm 2 .mol -1 , which are typical values for non electrolyte type (Geary,1971).

Magnetic susceptibility measurements
The magnetic moments of the complexes  ( Nicholls, 1973). The magnetic moments values of the other complexes (2-7, 9-14, 16-21, 23-28) were in the range (1. 58-5.36 B.M.) in an octahedral geometry. The high values of magnetic moments of some octahedral Co(ІІ) complexes from the spin only value are due to the orbital contribution. (Nicholls, 1973).

Electronic spectral studies
The UV-Visible spectra of the ligand and its complexes of 10 -3 M solution in DMF were recorded; the results were listed in Table (2). the UV-Visible spectra of the Fe(II) complex (1) gives absorption band at (9842cm -1 ), which corresponds to ( 5 E → 5 T 2 ) transition in a tetrahedral geometry (Nicholls, 1973). Complexes (2-7) show absorption band at the range (10217-11037.cm -1 ), which were assigned to ( 5 T 2 g→ 5 Eg) transition these observations indicating an octahedral geometry around Fe(II) ions ( Coucouvanis and Fackler, 1967).
For all compounds the other bands are refering to charge transfer and ligand transitiens.

Infra-red spectral studies
The important IR bands of the ligand (2-BuoEtXant)K and their complexes are listed in Table (2). The two bonds υ(C -O) and υ(C-S) of the ligand were observed at 1028 cm -1 and 1099cm -1 , in all complexes these bond shift to appear at the region (1130-1269)cm -1 and (1028-1072) cm -1 respectively. The presence of only one band in the later region reports the bidentate coordination of the dithio ligand (Serrano, 2003).
IR spectra showed a new band at (415-440) cm -1 which may be an is the evidence for the coordination of metal to sulfur υ(M-S). This behavior may be attributed to the electronreleasing of the alcohol, which forces high electron density towards the sulfur atoms (Rathore et al., 2007).  Fig. 1: Suggest structures (a) complexes [1, 8, 15