Binding H2, N2, H-, and BH3 to transition-metal sulfur sites:: Synthesis and properties of [Ru(L)(PR3)(N2Me2S2)] complexes (L = η2-H2, H-, BH3; R = Cy, iPr)

\The reactions of [Ru(N-2)-(PR3)(`N2Me2S2')] [`N2Me2S2'=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2- benzenethiolate)(2-)] [la (R=iPr), 1b (R=Cy)] and [mu-N-2{Ru(N-2)(PiPr(3))(`N2Me2S2')}(2)] (1c) with H-2, NaBH4, and NBu4BH4, intended to reduce the N-2 ligands, led to substitution of N-2 and formation of the new complexes [Ru(H-2)(PR3)(`N2Me2S2')] [2a (R=iPr), 2b (R=Cy)], [Ru(BH3)(PR3)(`N2Me2S2')] [3a (R= iPr), 3b (R=Cy)], and [Ru(H)(PR3)(`N2Me2S2')](-) [4a (R= iPr), 4b (R=Cy)]. The BH3 and hydride complexes 3a, 3b, 4a, and 4b were obtained subsequently by rational synthesis from la or 1b and BH3.THF or LiBEt3H. The primary step in all reactions probably is the dissociation of N-2 from the N-2 complexes to give coordinatively unsaturated [Ru(PR3)(`N2Me2S2')] fragments that add H-2, BH4-, BH3, or H-. All complexes were completely characterized by elemental analysis and common spectroscopic methods. The molecular structures of [Ru(H-2)(PR3)(`N2Me2S2')] [2a (R=iPr), 2b (R=Cy)], [Ru(BH3)(PiPr(3))(`N2Me2S2')] (3 a), [Li(THF)(2)] [Ru(H)(PiPr(3)) (`N2Me2S2')] ([Li(THF)(2)]-4a), and NBu4[Ru(H)(PCy3)(`N2Me2S2')] (NBu4-4b) were determined by X-ray crystal structure analysis. Measurements of the NMR relaxation time T-1 corroborated the H-2 bonding mode of the H-2 ligands in 2 a (T-1=35 ms) and 2b (T-1=21 ms). The H,D coupling constants of the analogous HD complexes HD-2a ((1)J(H,D) = 26.0 Hz) and HD-2b ((1)J(H,D)= 25.9 Hz) enabled calculation of the HD distances, which agreed with the values found by X-ray crystal structure analysis (2 a: 92 pm (X-ray) versus 98 pm (calculated), 2b: 99 versus 98 pm). The BH3 entities in 3a and 3b bind to one thiolate donor of the [Ru(PR3)(`N2Me2S2')] fragment and through a B-H-Ru bond to the Ru center. The hydride complex anions 4a and 4b are extremely Bronsted basic and are instantanously protonated to give the eta(2)-H-2 complexes 2a and 2b.