Synthesis of Trithia-Borinane Complexes Stabilized in Diruthenium Core: [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BR}] (R = H or SMe)

Abstract

The thermolysis of arachno-1 [(Cp*Ru)2(B3H8)(CS2H)] in the presence of tellurium powder yielded a series of ruthenium trithia-borinane complexes: [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BH}] 2, [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3B(SMe)}] 3, and [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BH}] 4. Compounds 2–4 were considered as ruthenium trithia-borinane complexes, where the central six-membered ring {C2BS3} adopted a boat conformation. Compounds 2–4 were similar to our recently reported ruthenium diborinane complex [(Cp*Ru){(η2-SCHS)CH2S2(BH2)2}]. Unlike diborinane, where the central six-membered ring {CB2S3} adopted a chair conformation, compounds 2–4 adopted a boat conformation. In an attempt to convert arachno-1 into a closo or nido cluster, we pyrolyzed it in toluene. Interestingly, the reaction led to the isolation of a capped butterfly cluster, [(Cp*Ru)2(B3H5)(CS2H2)] 5. All the compounds were characterized by 1H, 11B{1H}, and 13C{1H} NMR spectroscopy and mass spectrometry. The molecular structures of complexes 2, 3, and 5 were also determined by single-crystal X-ray diffraction analysis.

Synthesis, Structure, and Bonding of Bimetallic Bridging Borylene and Boryl Complexes

“…The average B–S bond distance of 1.824 Å is in accord with the sum of the covalent radii of B and S; however, this is shorter in comparison to [(Cp*Ru) 2 (μ-HBS 2 CH 2 -κ 2 B :κ 2 S ) 2 ] (1.7885 Å) . Similarly, the average C–S bond distance of 1.785 Å in the methanedithiolate unit of 4 is within the single-bond distance. , The 1 H chemical shift at δ 2.84 ppm and a resonance at δ 40.3 ppm in the 13 C­{ 1 H} NMR spectrum confirm the presence of a methanedithiolate ligand in 4 . The Ru–Ru bond distance of 2.6388(10) Å in 4 is significantly shorter in comparison to the ruthenium oxo-boryl species [{Cp*Ru­(μ-H)} 3 (μ 3 -BO)­(μ 3 -H)] (average 2.7162 Å) .…”

“…The B−S bond distances in 7 (1.809(3) and 1.826(3) Å) are within the range of a single-bond distance, as observed in other transition-metal−boron species. 15,22 This type of ruthenium complex stabilized by a simple boryl ligand is unique, and not many examples of this kind are known.…”

“…C-S bond distance of 1.785 Å in methanedithiolate unit of 4 is within the single bond distance. 22,23 The 1 H chemical shift at δ = 2.84 ppm and a resonance at δ = 40.3 ppm in 13 C{ 1 H} NMR spectrum confirms the presence of methanedithiolate ligand in 4. The Ru-Ru bond distance of 2.6388(10) Å in 4 is significantly shorter as compared to the ruthenium oxo-boryl species [{Cp*Ru(μ-H)}3(μ3-BO)(μ3-H)] (avg.…”