Synthesis of new Bismuth (III) compound and adducts of benzothiazol disulfide derivatives and their complexes with Co(II), Ni(II) and Cu(II)

Bismuth metal react with dibenzothiazole disulfide (C7H4NS2)2 in refluxing toluene to give the compound Bi(S2C7H4N)3 through oxidative addition reaction, similary, a mixture of bismuth, (C7H4NS2)2 and iodine in 1:1:0.5 molar ratio in refluxing toluene lead to the formation of Bi(S2C7H4N)2I. Adducts of new bismuth compounds with triphenylphosphine and 1,10-phenanthroline have been synthesized by direct reaction between the bismuth compounds and the neutral ligand. Trinuclear complexes of the general formula[Bi(S2C7H4N)3(MCl2)2] were prepared by a direct reaction of CoCl2.6H2O, NiCl2.6H2O or CuCl2.4H2O with bismuth compound. The bismuth compounds their adducts and the complexes have been characterized physico-chemically and spectroscopically. Synthesis of new Bismuth (III) compound and adducts of benzothiazol ... 2 Introduction The past decade has seen a period of intense activity in study of the complexation of transition metal and main group metal ions with thioether ligands (1-4) . Coordinated thiolato sulfur atoms tend to make bridges with a variety of metal ions, and considerable attention has been focused on the S-bridged polynuclear structure derived from [M(thiolato-S)2(amine-N)2]type (M=Ni(II), Pd(II)] mononuclear complexes (5-8) . The synthesis of dihalobis (2-pyridinethiolato) tin(IV) by an oxidative addition reaction of di-2-pyridyldisulfide to tin (II) halides represents an example of preparing other similar dihalodithiolato tin(IV) compounds (9) . In our previous studies (10,11) we have describe a direct reaction between bismuth or tin metal with (RC6H4S)2, (R=o-NH2, p-Me, p-Bu.t) refluxing toluene to give the corresponding comounds Bi(SC6H4R)3 and Sn(SC6H4R)4 respectively. Trinuclear complexes of the general formula [Sn(SC6H4NH2-o)4 (MCl2)2) {M=Ni(II),Pd(II) or Pt(II)} were prepared by a direct reaction of NiCl2.6H2O, Na2PdCl4 or K2PtCl4 with the tin compound (12) . In view of these interesting results and as continuation of our studies on transition and non-transition metal complexes with sulfurcontaining ligands (13-15) we have prepared the bismuth compound Bi(S2C7H4N)3, also, the derivatives with iodine and their adducts with neutral ligands, as well as the trinuclear complexes of general formula [Bi(S2C7H4N)3(MCl2)2]. Experimental General IR spectra were recorded on Tensor 27 Co.Brucker (FT.IR) Spectrophotometer in the (4000-250 cm -1 ) range using Nujol mulls or CsI disc. The metal content was estimated spectrophotometarically using Shimadzu AA670. Conductivity measurements were made on 10 -3 M solution of the complexes in dimethylsulfoxide (DMSO) solvent at ambient temperature using conductivity meter model 4070 Jenway. Electronic spectra were recorded on Shimadzu UV/Vis. Spectrophotometer UV-160 for 10 -3 M solution of the complexes in DMSO using 1cm quartz cell. The magnetic measurements were carried out at 25oC on the solid by Faraday's method using Burker BM6 instrument. Starting material Bismuth metal, toluene and dibenzothiazoldisulfide were commercial products (Fluka) and used as supplied. Nabeel. H. Buttrus & Z. U. Jassim 3 Preparation of Bismuth (III) compounds. 1Bi(S2C7H4N2)3. Finely cut bismuth metal (0.21 g, 1.0 mmol) and the disulfide (S2C7H4N)2 (0.48 g, 1.5 mmol) in toluene (30 cm 3 ) was refluxed for 8h. The reaction mixture was filtered through celite and the resultant solution was reduced to ca 10 cm 3 ,of its volume by evaporation under reduced pressure. The solid thus obtained after cooling in an ice-bath, was collected by filtration, washed with peteroleum ether (60-80oC) and dried in vacuo. 2Bi(S2C7H4N)2I. Finely cut bismuth metal (0.21 g, 1.0 mmol) was refluxed with the disulfide (0.33 g, 1.0 mmol) and iodine (0.064 g, 0.50 mmol) in toluene (30 cm 3 ) for 4h. The reaction mixture was filtered through celite and the resultant brown solution was reduced to ca 10 cm 3 of its volume by evaporation under reduced pressure. The solid thus obtained after cooling in an ice-bath, was collected by filtration, washed with peteroleum ether (60-80oC) and dried in vacuo. Preparation of Bi(S2C7H4N2)3 adducts: 3Bi(S2C7H4N2)3.2PPh3. The bismuth compound Bi(S2C7H4N2)3 (0.49 g, 10. mmol) was added to a solution of the ligand PPh3 (0.52 g, 2.0 mmol) in ethanol (20 cm 3 ) at room temperature. The reaction mixture was stirred for 4h., during which time a precipitate formed. It was collected by filtration, washed with ethanol, diethylether and dried in vacuo. 4Bi(S2C7H4N2)3.Phen. The bismuth compound Bi(S2C7H4N2)3 (0.49 g, 10. mmol) was stirred with 1,10-phenantholine (0.18 g, 1.0 mmol) in benzen (20 cm 3 ) for ca 2h., during which time a dark yellow oily layer was separated from the colourless solution and colourless layer was decanted. The oily layer was triturated with diethylether (30 cm 3 ) until it solidified and the resultant yellow solid was filtered, washed with ether and dried in vacuo. The analogous adducts Bi(S2C7H4N2)2I.2PPh3(5) or Bi(S2C7H4N2)2I. Phen (6) were prepared similarly. Preprartion of [Bi(S2C7H4N2)3(MCl2)2] complexes M= Co(II),Ni(II),Cu(II) A clear solution of Bi(S2C7H4N2)3 (0.49 g, 10. mmol) in methanol (10 cm 3 ) was added to a solution of CoCl2.6H2O or NiCl2.6H2O or CuCl2.6H2O (2.0 mmol) in distilled water (10 cm 3 ). The mixture was stirred under reflux for ca. 2h. the formed precipitate, was filtered off washed with methanol, and diethylether then dried under vacuo. Synthesis of new Bismuth (III) compound and adducts of benzothiazol ... 4 Results and Discussion The direct reaction of the ligand dibenzothiazole disulfide with bismuth metal in refluxing toluene using a 1:2 metal to ligand molar ratio afforded the compound Bi(S2C7H4N2)3 through an oxidative addition reaction (15) , also the reaction of iodine with disulfide and bismuth metal give a product of the formula Bi(S2C7H4N2)2I. The mechanism of these reactions involves the initial cleavage of the –S–S– bond to form the thiolate ion and the oxidation of bismuth metal from Bi 0 to Bi +3 . The reaction of the above compounds with neutral ligands were also reported. Treatment of the bismuth compound in alcohol with aqueous solution of metal chloride in (1:2) molar ratio gave the trinuclear complexes of the type [Bi(S2C7H4N2)3(MCl2)2]. The nucleophilicity of the thiolate sulfur atoms in the bismuth compound is responsible for the formation of these new complexes. The physical properties of the compounds and complexes are listed in (Table 1). The complexes are quite stable in dry air and melt or decompose at above than 135 oC. They are insoluble in most organic solvents but soluble in dimethylformamide. The most important IR assignment of bismuth compounds and their complexes are listed in Table 2. The infrared spectra of the ligand showed a sharp band at 1021 cm -1 attributed to C – S stretching vibration, which shifts to lower value in the compounds, indicating a coordination between sulfur and bismuth (16) , strong band in the 1580 cm -1 region, while were assigned to υ(C=N), the negligible effect on this frequency after complexation precludes the possibility of sharing of this group. Furthermore, the IR spectra of the adducts with PPh3 and Phen show a medium band at 985-990 cm -1 indicating that the ligand coordinated through sulphur atoms. Further support for this was obtained from the appearance of a new band at 323-336 cm -1 which assigned υ(Bi-S) while the υ(Bi-N) and υ(Bi-P) for 1,10-phenanthroline and triphenylphosphine are in good agreement with the reported values of In.X3.1.5phen (X=Cl,Br) which fall in the 410-450 cm -1 , while the υ(Bi-P) band is abserved at 480-510 cm -1 similar results was found some were else (18) . The frequency of υ(C-S) band observed at to 995-1005 cm -1 in the compounds is slightly decreased upon complexation with MCl2 to form the corresponding trinuclear complexes. Further support for the formation of new complexes is provided by the appearance of a new band at 340380 cm-1 range characteristic of bidentate trithiobismuth (17) , as shown below.