Reactions of Terminal and Bridging Thiol Di-μ-methylene Dirhodium Complexes with Alkynes to Afford the Corresponding Ethenethiolate Complexes. Remarkable C−C Bond Formation between Two μ-CH2 and Alkynes on the Bridging Ethenethiolate Complexes
“…14 Hz), is ascribed to the bridging hydrosulfide. A similar value of the SH chemical shift was reported for the dinuclear rhodium hydrosulfido complex [{Cp*Rh} 2 (μ-CH 2 ) 2 (μ-SH)] + …”
The dicationic complex [(triphos)Rh(mu-S)(2)Rh(triphos)](2+), 1 (modeled as 1c) [triphos = CH(3)C(CH(2)PPh(2))(3)], is known to activate two dihydrogen molecules and produce the bis(mu-hydrosulfido) product [(triphos)(H)Rh(mu-SH)(2)Rh(H)(triphos)](2+), 2 (modeled as 2b), from which 1 is reversibly obtained. The possible steps of the process have been investigated with DFT calculations. It has been found that each d(6) metal ion in 1c, with local square pyramidal geometry, is able to anchor one H(2) molecule in the side-on coordination. The step is followed by heterolytic splitting of the H-H bond over one adjacent and polarized Rh-S linkage. The process may be completed before the second H(2) molecule is added. Alternatively, both H(2) molecules are trapped by the Rh(2)S(2) core before being split in two distinct steps. Since the ambiguity could not be solved by calculations, (31)P and (1)H NMR experiments, including para-hydrogen techniques, have been performed to identify the actual pathway. In no case is there experimental evidence for any Rh-(eta(2)-H(2)) adduct, probably due to its very short lifetime. Conversely, (1)H NMR analysis of the hydride region indicates only one reaction intermediate which corresponds to the monohydride-mu-hydrosulfide complex [(triphos)Rh(H)(mu-SH)(mu-S)Rh(triphos)](2+) (3) (model 5a). This excludes the second hypothesized pathway. From an energetic viewpoint the computational results support the feasibility of the whole process. In fact, the highest energy for H(2) activation is 8.6 kcal mol(-1), while a larger but still surmountable barrier of 34.6 kcal mol(-1) is in line with the reversibility of the process.
“…14 Hz), is ascribed to the bridging hydrosulfide. A similar value of the SH chemical shift was reported for the dinuclear rhodium hydrosulfido complex [{Cp*Rh} 2 (μ-CH 2 ) 2 (μ-SH)] + …”
The dicationic complex [(triphos)Rh(mu-S)(2)Rh(triphos)](2+), 1 (modeled as 1c) [triphos = CH(3)C(CH(2)PPh(2))(3)], is known to activate two dihydrogen molecules and produce the bis(mu-hydrosulfido) product [(triphos)(H)Rh(mu-SH)(2)Rh(H)(triphos)](2+), 2 (modeled as 2b), from which 1 is reversibly obtained. The possible steps of the process have been investigated with DFT calculations. It has been found that each d(6) metal ion in 1c, with local square pyramidal geometry, is able to anchor one H(2) molecule in the side-on coordination. The step is followed by heterolytic splitting of the H-H bond over one adjacent and polarized Rh-S linkage. The process may be completed before the second H(2) molecule is added. Alternatively, both H(2) molecules are trapped by the Rh(2)S(2) core before being split in two distinct steps. Since the ambiguity could not be solved by calculations, (31)P and (1)H NMR experiments, including para-hydrogen techniques, have been performed to identify the actual pathway. In no case is there experimental evidence for any Rh-(eta(2)-H(2)) adduct, probably due to its very short lifetime. Conversely, (1)H NMR analysis of the hydride region indicates only one reaction intermediate which corresponds to the monohydride-mu-hydrosulfide complex [(triphos)Rh(H)(mu-SH)(mu-S)Rh(triphos)](2+) (3) (model 5a). This excludes the second hypothesized pathway. From an energetic viewpoint the computational results support the feasibility of the whole process. In fact, the highest energy for H(2) activation is 8.6 kcal mol(-1), while a larger but still surmountable barrier of 34.6 kcal mol(-1) is in line with the reversibility of the process.
Reaction of trans-[(MCp)(2)(mu-CH(2))(2)Cl(2)] (M = Rh, Ir; Cp = eta(5)-C(5)Me(5)) with Li(2)S(2) afforded the disulfido complexes [(MCp)(2)(mu-CH(2))(2)(mu-S(2)-S:S')] which were easily oxidized by O(2) to give the oxygenated complexes [(MCp)(2)(mu-CH(2))(2)(mu-SSO(2)-S:S')]. Although [(RhCp)(2)(mu-CH(2))(2)(mu-S(2)-S:S')] gave a complicated mixture when reacted with CH(2)Cl(2) or CHCl(3), [(IrCp)(2)(mu-CH(2))(2)(mu-S(2)-S:S')] reacted with both CH(2)Cl(2) and CHCl(3) to give the dithioformato complex [(IrCp)(2)(mu-CH(2))(2)(mu-S(2)CH-S:S')]Cl and the cyclotetrasulfido complex [((IrCp)(2)(mu-CH(2))(2))(2)(mu-S(4)-S:S':S":S"')]Cl(2). The oxygenated complexes [(RhCp)(2)(mu-CH(2))(2)(mu-SSO(2)-S:S')] reacted with hydrocarbyl halides to afford bridging hydrocarbyl thiolato complexes accompanied by the generation of SO(2) gas. These complexes have been characterized by NMR spectroscopy, ESI-MS, and X-ray diffraction.
“…Examples of complexes having single carbon−sulfur bonds such as M−SCHCH 2 (M = metals) are not so many, and only several complexes are known that were obtained by the ring-opening of 1,4,7-trithiacyclononane ([9]aneS 3 ) ligand in the complexes [M([9]aneS 3 ) 2 ] 3+ and related ones (M = Co, Ru, Rh, Ir) − through deprotonation (Scheme ). There are a number of other metal complexes with vinyl thiolate ligands that have been reported. − These include derivatives prepared from vinyl halides and by S−H addition to acetylenes. ,, The chemistry of vinyl sulfide metallacycle complexes of molybdenum has also been reported 2 Reaction of [(CpMo) 2 (μ-S 2 CH 2 )(μ-S) 2 ] with Phenylacetylene 3 Deprotonation of [M([9]aneS 3 ) 2 ] 3+ ([9]aneS 3 = 1,4,7-Trithiacyclononane; M = Co, Rh, Ir,) …”
Formation of a single carbon-sulfur bond is described. The reaction of incomplete cubane-type sulfur and oxygen-bridged isothiocyanato tungsten cluster [W3(mu3-S)(mu-O)(mu-S)2(NCS)9]5- (7) with acetylene affords [W3(mu3-S)(mu-O)(mu-S)(mu-SCH=CH2)(NCS)9]4- (8). The cluster 8 has been isolated as K0.5(Hpy)3.5[W3(mu3-S)(mu-O)(mu-S)(mu-SCH=CH2)(NCS)9] (8'), whose structure has been characterized by X-ray crystallography, electronic spectra, and 1H and 13C NMR spectroscopy. Crystal data of 8': triclinic system, space group P1, a = 14.465(5) A, b = 17.353(3) A, c = 10.202(2) A, alpha = 90.98(1) degrees, beta = 108.59(2) degrees, gamma = 98.13(2) degrees, V = 2397.6(10) A(3), Z = 2, D(c) = 2.096 g cm(-3), Dm = 2.08 g cm(-3), R (Rw) = 3.6 (5.5)% for 8786 reflections (I > 1.50 sigma(I)). The carbon-carbon distance is 1.27(1) A and is almost equidistant between ethylene (1.339 A) and acetylene (1.203 A). The electronic spectrum of 8' in 1.0 M HCl containing 1.5 M KSCN has a characteristic broad peak in the near-infrared region [lambda(max), nm (epsilon, M(-1) cm(-1)): 840 (650), 575 (1450)]. (1)H NMR and HH correlation spectroscopy (COSY) of 8' in CD3CN support the results of the X-ray structural analysis. The (1)H NMR spectrum shows three signals at 2.42 (1H, dd), 4.84 (1H, d, J = 8.8 Hz), and 4.89 (1H, d, J = 16.2 Hz) ppm due to the mu-SCH=CH2 moiety of 8'. The correlation spectrum shows spin couplings of the signal at 2.42 ppm with the signals at 4.84 and 4.89 ppm. The mechanism of the formation of 8 is suggested to proceed through an intermediate with acetylene bridging two of the sulfur atoms.
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