Transition Met. Chem., 17, 557-559 (1992) Hexahydro-l,3-diazepine-2-thione Au ~ complexes 557 Synthesis of bis- and multinuclear gold(I) complexes of hexahydro- 1,3-diazepine-2-thione Anvarhusein A. Isab*, Herman P. Perzanowski and Abdul Rehman A. AI-Arfaj Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia 31261 Summary New Ois- and multinuclear Au ~ complexes of the type [Au(Diap)2]X and [Au2(Diap)3X2], where Diap = hexa- hydro-l,3-diazepine-2-thione, have been prepared and characterized. The spectroscopic studies reveal that both free Diap and its Au ~complexes exist in the thione form in the solid as well as the solution state. The ~3C-n.m.r. chemical shift of the C-2 resonance indicates that Diap binds more strongly to Au ~ compared to the analogous five membered imidazolidine-2-thione and six membered 1,3-diazinane-2-thione. Introduction The coordination chemistry of the thiamido group- NHCS, in heterocyclic penta- and hexa-atomic rings, such as imidazolidine-2-thione (Imt) and 1,3-diazinane-2-thione (Diaz) and their derivatives, has been the subject of several recent studies ~1-8~. These ligands are important because they form stable complexes with various metal ions tt-8~. Although Imt and Diaz have been extensively investigated, the analogous ligand hexahydro-l,3-diazepine-2-thione (Diap) has not been studied in detail. In this paper, we describe the new complexes [Au(Diap)2]Cl and [Au2- (Diap)3C12] and characterize them on the basis of analytical and i.r., 1H- and ~3C-n.m.r. spectroscopic data. s s s Irnt Dtaz Diap Experimental All chemicals were obtained from Fluka. The ligands were prepared as reported in the literature t9'I~ Preparation of [ Au( Diap )2]Cl Diap was dissolved in MeOH and NaAuC14 was dissolved in doubly deionized distilled H20. A L:M ratio of 4:1 was used. When the metal solution was added to the ligand, an orange residue formed, which dissolved on stirring to give a white precipitate tt 1.12). The precipitate was washed with MeOH and dried in vacuo. Analytical data are given in Table 1. Preparation of [ Au2( Diap )3Cl2] The NaAuCl 4 was reduced to Au ~ by bubbling SO2 gas through the aqueous solution as described in the literature~l,a2). When the yellow Aum solution became colourless, Diap was added to give a Au ~ to ligand ratio * Author to whom all correspondenceshould be directed. Table 1. Analytical data for gold(I) complexes. The correspond- ing calculated values are given in parentheses. Complex Dec. P. Colout" Found (Calcd.)~o (~ and form H C N [Au(Diap)2]C1 180~ White 4.3 25.3 12.2 powder (4.0) (26.4) (11.4) [Au2(Diap)3C12] 190 ~ Orange 3.6 21.8 10.2 powder (3.7) (22.0) (10.2) of 1 : 1. Although the expected product was a white [AuLX] type mononuclear white complex tl 1,12), an orange powder was formed and analysis suggested a [Auz(Diap)3Cl2] type muttinuclear complex. The data for this complex are given in Table 1. Spectroscopic measurements i.r. Spectra of Diap and its complexes were obtained on a Perkin-Elmer IR 180 or on a Beckman Microlab Spectro- photometer using KBr pellets. Proton and 13C-n.m.r. spectra were recorded on a Bruker AC-80 spectrometer operating at 80 and 20.1MHz frequency, respectively. Diap and complexes were dissolved in DMSO-d6. The internal reference was 1,4-dioxane. Results and discussion Bis- and multinuclear Diap. Their analytical Au ~ complexes were formed with data are given in Table 1. I.r. spectral studies The i.r. spectra of free Diap and its gold(l) complexes (Table 2) show neither S--H absorptions in the 2500 cm- 1 region, nor a C~---N band at 1700-1590 cm- 1, but exhibit a strong absorption at ca. 3150cm-1 corresponding to the NH stretch ~13) The presence of a band at 3150 cm- i in free Diap as well as in the gold(I) complexes clearly shows the existence of a thione function. In our previous study ~12), the Au--S band for various gold(I) thione complexes was observed at ca. 345 cm- 1; a similar band was observed for both the complexes under study here indicating that gold(I) is bonded via the sulphur of the ligand. A shift of ca. 40cm- 1 in the v(C=S) band also supports this conclusion. 1H-n.m.r. studies The ~H-n.m.r. chemical shifts for free Diap and its complexes are reported in Table 3. It is noted that no significant shifts were observed for the H-5, 6 and H-4, 7 protons. However, in the complexes under investigation the NH-1,3 protons were shifted by 1.3 ppm. Integration of the NH-1, 3 and H-4, 7 protons gave a 1 : 2 ratio, sug- gesting that in solution Diap exists as the thione for/n in 0340-4285 9 1992 Chapman &Hall