Carbon−Sulfur Bond Formation via Alkene Addition to an Oxidized Ruthenium Thiolate

Bulk oxidation of [Ru(DPPBT)3], 1b, (DPPBT = 2-diphenylphosphinobenzenethiolate) in the presence of ethylene
yields [(ethane-1,2-diylbis(thio-2,1-phenylene)diphenylphosphine) ruthenium(II)] hexafluorophosphate, [2a]PF6, from
the addition of the alkene across cis sulfur sites. During oxidation, the absorption bands of 1b at 540, 797, and
1041 nm decrease in intensity. The resulting complex [2a]+ displays a single redox couple at +804 mV. The
+ESI-MS of [2a]+ shows a parent ion peak at m/z = 1009.1013, and the 31P NMR spectrum displays chemical
shift values of δ1 = 61.0, δ2 = 40.3, and δ3 = 37.5 with coupling constants of J12 ≈ J13 ≈ 30 Hz and J23 = 304
Hz. Oxidation of [2a]+ by one electron at a holding potential of +1000 mV yields [(ethane-1,2-diylbis(thio-2,1-phenylene)diphenyl phosphine)ruthenium(III)] hexafluorophosphate, [2b][PF6]2. The EPR of [2b][PF6]2 displays a
rhombic signal with g1 = 2.09, g2 = 2.04, and g3 = 2.03. Oxidation of 1b in the presence of alkenes including
1-hexene, styrene, cyclohexene, and norbornene yields products similar to [2a]+. Each of these products was
further oxidized to an analogue of [2b]2+. Complex [2a]+ was also prepared, as the bromide salt, from [PPN][Ru(DPPBT)3] (PPN [1a]; PPN = bis(triphenylphosphoranylidene)ammonium) and 1,2-dibromoethane. The complex
[2a]Br crystallizes as thin yellow plates in the monoclinic space group P21/c with unit cell dimensions of a =
10.2565(9) Å, b = 13.2338(12) Å, c = 38.325(3) Å, and β = 93.3960(10)°.