Tiyoeter ve amidoksim gruplu, dört dişli iki yeni ligand sentezi ve bunların makrohalkalı metal kompleksleri

Abstract

Bu çalışmada 1.2-etanditiyolden yola çıkılarak kükürt ve amidoksim grupları taşıyan 4 dişli iki yeni ligand elde edilmiştir. i-b Her iki ligandın Ni (II), Cu CII) ve Co (II) ile 1:1 L/M oranında cis kompleksleri meydana getirdiği anlaşılmıştır Kompleksleşmelerin yalnız amidoksim grupları üzerinden yürümediği, S atomlarının da koordinasyona dahil olduğu (+1) yüklü metal komplekslerinin oluştuğu kanıtlanmıştır.,NH, 1 N-0N ?-s' N- O'' 'NH2 Mla,S N-0\ M ^S N-0 H NH, MLb Cf Bu komplekslerin elektrolitik indirgenmesi ile Ni (I), Co (I) gibi alışılmışın dışındaki yükseltgenme basamağında metal iyonu komplekleri elde edilememiş, bunun yerine katotta hidrojen çıkışı gözlenmiştir.

In the present study two new ligands with amidoxim and thioether groups have been prepared starting from 1,2-ethanedithiol by condensation with chloroacetonitrile and by Michael Addition with acrylonitrile. The resulting dinitriles have been reacted to form amidoxime compounds. Overall reaction schemes have been outlined as follows: HS SH NI-bOH HON HS SH \ / * CH2=CH -CN NH7OH HON Having both sulfide and amidoxime functions in the molecules these compounds have been expected possible physiological activities against some tumors VI and also AIDS. Indeed after purification and crystalization these two compounds have been submitted to the Department of Health and Human Services, USA, dealing mainly with antitumor drugs. In the light of the preliminary experiments against HIV were found to be unsuccesful. Later on an extensive study of their activities against nine different kind of tumor (leukemia, non-small cell lung cancer, colon cancer, CNS cancer, melanoma, overian cancer, renal cancer, prostate canser, breast cancer) have been performed in vitro conditions by National Institute of Health, USA. Although few experiments show some positive activities against to prostate tumors overall results give no promise for an efficient antitumor activity. However their metal complexes will be taken into consideration in this respect as well. These compounds, carrying sulfide and amidoxime groups have been interacted with Ni(II), Cu(II) and Co(II) ions in alcoholic solution to form corresponding metal complexes. Metal complexes have shown to be 1:1 L/M complexes in macrocyclic form. All these complexes are monocharged cationic complexes. HON H,N + MCİ2 NOH H,NV il HON NOH "NH2 + MCİ2 c Sv N-0\ M H S N-O k^U NH, -A- CI d-d transitions of all the metal complexes observed in visible range reveals that, these complexes, except CoLb have to be in planar structure. These results have been confirmed by magnetic susceptibility measurements. However the number of Vll nonpaired electrons by spin only formula are not matched with those of the regular square planar arrangements. Because planar conformation of the metal complexes are in C2v point group of symetry, not in D4h. In the last stage of the study we have investigated the possibility of preparing neutral complexes by electrolytic reduction. For this purpose the solution of metal complexes in DMSO were electrolized at 5-6 Volt (including potential difference of the ohmic resistivity of the solution) and 8-10 miliamper using graphite electrodes in the presence of tetrabutilamonium perchlorate as supporting electrolyte. During the electrolysis we observed not only chlorine evolution from the anode but also evolution of hydrogen from the cathode. Cathode surface was also covered by insoluble complexes, which differ in color. So attempts to obtain neutral complexes in which metal ions with unusual oxidation states such as Ni(I), Cu(I) and Co(I) were all failed. Even in the case of Cu(II) complexes hydrogen evolution occurs instead of the formation of Cu(I) complexes. In each case the bridged hydrogen in the complexes are reduced to give elemental hydrogen resulting in metal (II) complexes neutralized by the oximate units as in the following: -,+ a +e~ To elucidate of the structure of electrolysis products is beyond the scope of the present study. So we have no interest in the characterization of electrolysis products. Consequently, the most important results of the study can be summarized as follows: via 1- The ligands behave as tetradentate ligands and give macrocyclic chelates No polymerization occurs in the complexation. The role of metal ions can be regard as metal templated macrocyclization as known many examples in the literature [1]. 2- No preference for coordination only oxime groups due to formation of five or six membered chelate rings including sulfide groups. The resulting structures are monocharged cationic complexes with chlorine atom as counter anions. Magnetic susceptibilities and visible spectrums have been used to elucidate the conformation of the metal complexes. Ni(II) complexes of the two ligands have found to be diamagnetic. This result reveals that both Ni(II) complexes are in planar coordination structure. Whereas Co(II) complexes of the second ligand exhibits three nonpaired electrons indicating its nonplanar conformation. This complex should have tetrahedral arrangement. On the other hand, CoLa complex shows only one unpaired electron, that means planar coordination. However having sulfur and amidoxime ligating groups, this ligand can not form a regular square planar complex with Co(II) ion. Hence this complex must have C2v point group of symmetry instead of D4h point group. Unfortunately magnetic susceptibilities of the Cu(II) complexes do not give information about their coordination shapes. Because both planar and tetrahedral complexes of Cu(II) have one unpaired electron. For this reason it is not impossible to make any difFerantation in the two conformation depending on their magnetic susceptibility measurements. However their absorbtion wavelengths in visible range indicate that Cu(II) complexes are in planar structure. 3- Electrolitic reduction of the complexes give no products in which metal ions are in (+1) oxidation states. Instead reduction of hydrogen between the two oxime units is prevailed with respect to reduction of metal itself. Also chlorine evolution from the cathode is osberved clearly. The colour of the resulting electrolysis products are different from their corresponding starting counterparts. ix From thermodynamical point of view, reduction of the bridged hydrogen needs less energy. Consequently hydrogen evolution is favour in comparision to reduction of the complexed metal ion. We have not interested to elucidate the electrolysis products. But in these complexes metal ions should bind through the oxygen atoms of oxime groups.