RESUMEN
The syntheses and structural elucidation of bimetallic thiolate complexes of early and late transition metals are described. Thermolysis of the bimetallic hydridoborate species [{Cp*CoPh}{µ-TePh}{µ-TeBH3-ĸ2Te,H}{Cp*Co}] (Cp* = ɳ5-C5Me5) (1) in the presence of CS2 afforded the bimetallic perthiocarbonate complex [(Cp*Co)2(µ-CS4-κ1S:κ2S')(µ-S2-κ2Sâ³:κ1Sâ´)] (2) and the dithiolene complex [(Cp*Co)(µ-C3S5-κ1S,S'] (3). Complex 2 contains a four-membered metallaheterocycle (Co2S2) comprising a perthiocarbonate [CS4]2- unit and a disulfide [S2]2- unit, attached opposite to each other. Complex 2 was characterized by employing different multinuclear NMR, infrared spectroscopy, mass spectrometry, and single-crystal X-ray diffraction studies. Preliminary studies show that [Cp*VCl2]3 (4) with an intermediate generated from CS2 and [LiBH4·THF] yielded thiolate species, albeit different from the cobalt system. Furthermore, a computational analysis was performed to provide insight into the bonding of this bimetallic perthiocarbonate complex.
RESUMEN
Syntheses, structures, and electronic properties of group 5 metal-thiolate complexes that exhibit unusual coordination modes of thiolate ligands have been established. Room-temperature reaction of [Cp*VCl2]3 (Cp* = η5-C5Me5) with Na5[B(SCH2S)4] led to the formation of [Cp*VO{(SCH2)2S}] (1). The solid-state X-ray structure of 1 shows the formation of six-membered l,3,5-trithia-2-vanadacyclohexane that adopted a chair conformation. In a similar fashion, reactions of heavier group 5 precursors [Cp*MCl4] (M = Nb or Ta) with Na5[B(SCH2S)4] yielded bimetallic thiolate complexes [(Cp*M)2(µ-S){µ-C(H)S3-κ2S:κ2S',Sâ³}{µ-SC(H)S-κ2C:κ2Sâ´,S''''}] (3a: M = Nb and 3b: M = Ta). One of the key features of molecules 3a and 3b is the presence of square-pyramidal carbon, which is quite unusual. The reactions also yielded bimetallic methanedithiolate complexes [(Cp*Nb)2(µ-S)(µ-SCH2S-κ2S,S')(µ,η2:η2-BH3S)] (2) and [(Cp*Ta)2(µ-O)(µ-SCH2S-κ2S,S')(µ-H){µ-S2C(H)SCH2S-κ2Sâ³:κ2Sâ´,S''''}] (4). Complex 2 contains a methanedithiolate ligand that stabilizes the unsaturated niobaborane species. On the other hand, one ((mercaptomethyl)thio)methanedithiolate ligand {C2H4S3} is present in 4, which is coordinated to metal centers and exhibits the {µ-κ2Sâ³:κ2Sâ´,S''''} bonding mode. Along with the formation of 3b and 4, the reaction of [Cp*TaCl4] with Na5[B(SCH2S)4] yielded [(Cp*Ta)2(µ-S){µ-(SBS)S(CH2S)2(BH2S)-κ2B:κ2S:κ4S',Sâ³,Sâ´,S''''}] (5) containing a trithiaborate unit (BS3). Complex 5 consists of pentacoordinate boron that resides in a square-pyramidal environment. All the complexes have been characterized by multinuclear NMR, UV-vis spectroscopy, mass spectrometry, and single-crystal X-ray diffraction studies.
RESUMEN
A series of hydroborated η4-σ,π-alkene-borane complexes have been synthesized from the reaction of ruthenium-bis(σ)borate complex [Cp*Ru(µ-H)2BH(S-CHâS)] (1) and terminal as well as internal alkynes. Likewise, the reactions of manganese-bis(σ)borate complexes [Mn(CO)3(µ-H)2BHNCSC6H4(NL)] (L = NCSC6H4 or H) were explored with terminal alkynes that yielded boratabutadiene complexes [Mn(CO)3{(NCSC6H4)2N}{(R1MeC)âB(HCâCHR1)}] [R1 = phenyl (4a) or p-tolyl (4b)] via triple hydroboration of alkynes. These complexes feature a boratabutadiene ligand that is coordinated to a metal through the η4-CBCC mode. To the best of our knowledge, these are the first examples of η4-E-boratabutadiene-coordinated manganese complexes generated by the trans-hydroboration of alkynes. The steric and electronic effects of the borate ligands have been demonstrated using a less sterically hindered manganese-bis(σ)borate complex, [Mn(CO)3(µ-H)2BH(HN2CSC6H4)], that generated monohydroborated complexes [(CO)3Mn(µ-H)2(HN2CSC6H4)B(R1CâCHR2)] (for 6, R1 = Ph and R2 = H; for 7, R1 = p-Tol and R2 = H; for 8, R1 = R2 = Ph). Theoretical studies using density functional theory methods and chemical bonding analyses established the bonding and stability of these species.
RESUMEN
The field of diborinane is sparsely explored area, and not many compounds are structurally characterized. The room-temperature reaction of [{Cp*RuCl(µ-Cl)}2] (Cp* = η5-C5Me5) with Na[BH3(SCHS)] yielded ruthenium dithioformato [{Cp*Ru(µ,η3-SCHS)}2], 1, and 1-thioformyl-2,6-tetrahydro-1,3,5-trithia-2,6-diborinane complex, [(Cp*Ru){(η2-SCHS)CH2S2(BH2)2}], 2. To investigate the reaction pathway for the formation of 2, we carried out the reaction of [(BH2)4(CH2S2)2], 3, with 1 that yielded compound 2. To the best of our knowledge, it appears that compound 2 is the first example of a ruthenium diborinane complex where the central six-membered ring [CB2S3] adopts the chair conformation. Furthermore, room temperature reaction of 1 with [BH3·thf] resulted in the isolation of agostic-bis(σ-borate) complex, [Cp*Ru(µ-H)2BH(S-CHâS)], 4. Thermolysis of 4 with trace amount of tellurium powder led to formation of bis(bridging-boryl) complex, [{Cp*Ru(µ,η2-HBS2CH2)}2], 5, via dimerization of 4 followed by dehydrogenation. Compound 5 can be considered as a bis(bridging-boryl) species, in which the boryl units are connected to two ruthenium atoms. Theoretical studies and chemical bonding analyses demonstrate the reason for exceptional reactivity and stability of these complexes.
RESUMEN
The synthesis, structure and electronic properties of tetraruthenium dichalcogenide complexes displaying the exclusive coordination mode of dichalcogenide ligands have been discussed. The reactions of Li[BH2E3] (E = S or Se) with [ClRu(µ-Cl)(p-cymene)]2 (p-cymene = η6-{p-C6H4(iPr)Me}) at room temperature yielded tetrametallic dichalcogenide complexes [{Ru2Cl2(p-cymene)2}2(µ4,η2-E2)], 1-2 (E = S (1) and Se (2)). The solid-state X-ray structure of 1 shows that two {(p-cymene)RuCl}2 moieties are bridged by a S-S bond. In addition to 2, the reaction of Li[BH2Se3] with [ClRu(µ-Cl)(p-cymene)]2 also yielded a mononuclear tris-homocubane analogue [Ru(p-cymene){Se7(BH)3}] (3) which is an analogue of 1,3,3-tris-homocubane and possesses D3 symmetry. In order to isolate the Cp* analogue of 1, the reaction of [Cp*Ru(µ-Cl)Cl]2 with Li[BH2S3] was carried out, which led to the formation of bis/tris-homocubane derivatives [(Cp*Ru)2{µ-Sn(BH)2}] (n = 7 (4) and 6 (5)) along with the formation of ruthenium disulfide complexes [(RuCp*)2(µ,η2:η2-S2)(µ,η1:η1-S2)] and [(RuCp*)2(µ-SBHS-κ1B:κ2S:κ2S)(µ,η1:η1-S2)]. Complexes 1-5 have been characterized by multi-nuclear NMR, IR, UV-vis spectroscopy, and mass spectrometry and their molecular formulations (except 2) have been determined by single crystal X-ray crystallography. Furthermore, DFT calculations were performed that rationalize the stabilization of the dichalcogenide units (E22-) by the tetrametallic systems in 1-2.