Synthesis and reactivity of ruthenium complexes with 1,1′-dithiolate ligands

Abstract

Reactions of [Ru(PPh 3) 3Cl 2] with ROCS 2K in THF at room temperature and at reflux gave the kinetic products trans-[Ru(PPh 3) 2(S 2COR) 2] (R = n Pr 1, i Pr 2) and the thermodynamic products cis-[Ru(PPh 3) 2(S 2COR) 2] (R = n Pr 3, i Pr 4), respectively. Treatment of [RuHCl(CO)(PPh 3) 3] with ROCS 2K in THF afforded [RuH(CO)-(S 2COR)(PPh 3) 2] (R = n Pr 5, i Pr 6) as the sole isolable products. Reaction of [RuCl 2(PPh 3) 3] with tetramethylthiuram disulfide [Me 2NCS 2] 2 gave a Ru(III) dithiocarbamate complex, [Ru(PPh 3) 2(S 2CNMe 2)Cl 2] ( 7). This reaction involved oxidation of ruthenium(II) to ruthenium(III) by the disulfide group in [Me 2NCS 2] 2. Treatment of 7 with 1 equiv. of [M(MeCN) 4][ClO 4] (M = Cu, Ag) gave the stable cationic ruthenium(III)–alkyl complexes [Ru{C(NMe 2)QC(NMe 2)S}(S 2CNMe 2)(PPh 3) 2][ClO 4] (Q = O 8, S 9) with ruthenium–carbon bonds. The crystal structures of complexes 1, 2, 4·CH 2Cl 2, 6, 7·2CH 2Cl 2, 8, and 9·2CH 2Cl 2 have been determined by single-crystal X-ray diffraction. The ruthenium atom in each of the above complexes adopts a pseudo-octahedral geometry in an electron-rich sulfur coordination environment. The 1,1′-dithiolate ligands bind to ruthenium with bite S–Ru–S angles in the range of 70.14(4)–71.62(4)°. In 4·CH 2Cl 2, the P–Ru–P angle for the mutually cis PPh 3 ligands is 103.13(3)°, the P–Ru–P angles for other complexes with mutually trans PPh 3 ligands are in the range of 169.41(4)–180.00(6)°. The alkylcarbamate [C(NMe 2)QC(NMe 2)S] − (Q = O, S) ligands in 8 and 9 are planar and bind to the ruthenium centers via the sulfur and carbon atoms from the C S and N C double bonds, respectively. The Ru–C bond lengths are 1.975(5) and 2.018(3) Å for 8 and 9·2CH 2Cl 2, respectively, which are typical for ruthenium(III)–alkyl complexes. Spectroscopic properties along with electrochemistry of all complexes are also reported in the paper.