A series of five coordinated iron bis(dithiolene)complexes[Fe(NHC)(S_(2)C_(2)R_(2))_(2)](R=C_(6)H_(5)or C_(6)H_(4)-p-OCH_(3))containing N-heterocyclic carbene(NHC)(NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene ...A series of five coordinated iron bis(dithiolene)complexes[Fe(NHC)(S_(2)C_(2)R_(2))_(2)](R=C_(6)H_(5)or C_(6)H_(4)-p-OCH_(3))containing N-heterocyclic carbene(NHC)(NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene or 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene)were isolated in high yield(84–92%).The iron complexes were characterized by NMR spectroscopy and confirmed by single crystal X-ray diffraction studies.展开更多
Imidazolyl amino cuboidal Mo_(3)(μ_(3)-S)(μ-S)_(3)clusters have been investigated as catalysts for the semihydrogenation of alkynes.For that purpose,three new air-stable cluster salts[Mo_(3)S_(4)Cl_(3)(ImNH_(2))_(3)...Imidazolyl amino cuboidal Mo_(3)(μ_(3)-S)(μ-S)_(3)clusters have been investigated as catalysts for the semihydrogenation of alkynes.For that purpose,three new air-stable cluster salts[Mo_(3)S_(4)Cl_(3)(ImNH_(2))_(3)]BF_(4)([1]BF_(4)),[Mo_(3)S_(4)Cl_(3)(ImNH(CH_(3)))_(3)]BF_(4)([2]BF_(4))and[Mo_(3)S_(4)Cl_(3)(ImN(CH_(3))_(2))_(3)]BF_(4)([3]BF_(4))have been isolated in moderate to high yields and fully characterized.Crystal structures of complexes[1]PF6 and[2]Cl confirm the formation of a single isomer in which the nitrogen atoms of the three imidazolyl groups of the ligands are located trans to the capping sulfur atom which leaves the three bridging sulfur centers on one side of the trimetallic plane while the amino groups lie on the opposite side.Kinetic studies show that the cluster bridging sulfurs react with diphenylacetylene(dpa)in a reversible equilibrium to form the corresponding dithiolene adduct.Formation of this adduct is postulated as the first step in the catalytic semihydrogenation of alkynes mediated by molybdenum sulfides.These complexes catalyze the(Z)-selective semihydrogenation of diphenylacetylene(dpa)under hydrogen in the absence of any additives.The catalytic activity lowers sequentially upon replacement of the hydrogen atoms of the N-H_(2)moiety in 1+without reaching inhibition.Mechanistic experiments support a sulfur centered mechanism without participation of the amino groups.Different diphenylacetylene derivatives are selectively hydrogenated using complex 1+to their corresponding Z-alkenes in excellent yields.Extension of this protocol to 3,7,11,15-tetramethylhexadec-1-yn-3-ol,an essential intermediate for the production of vitamin E,affords the semihydrogenation product in very good yield.展开更多
The reaction of CuCl2-2H2O or NiCl2.6H2O with K2(C5H6S4) [potassium salt of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]- or [Ni(C5H6S4)2]- as the t...The reaction of CuCl2-2H2O or NiCl2.6H2O with K2(C5H6S4) [potassium salt of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]- or [Ni(C5H6S4)2]- as the tetrabutylammonium salt. Both complexes show characteristic IR and UV-Vis absorptions of transition metal dithiolenes. Cyclic voltammograms contain two waves indicating a two step electrochemical procedure [M(C5H6S4)2]0 = [M(C5H6S4)2]1-= [M(C5H6S4)2]2-. Single crystal structure study has been carried out on the nickel complex. Crystal of [Bu4N][Ni(C5H6S4)2] belongs to monoclinic space group P21/c with a=17.576(5), 6=10.883(2), c=17.773(4) A,B=91.07(2)0, Z=4, and o(calcd.)=1.348 g/cm3. Final result is R=0.059 for 2959 reflections. The NiS4 core exhibits square planar coordination with average Ni-S bond length of 2.134(5) A. There are not anion pairs in crystal. The anions stack along a and c axes while the cations intercalate in them. The nearest S-S contact is 4.429 A. The solid powder ESR spectrum of the nickel complex shows three broadening signals at g1=2.097, g2=2.042, g3=2.022. Magnetic susceptibility data for [Bu4N][Ni(CgH6S4)2] reveal enhanced anti-ferromagnetic interaction.展开更多
基金support by funds from the Army Research Office(Department of DefenseW911NF-16-1-0197)+1 种基金funds from The American Chemical Society Petroleum Research Fund(PRF-59893-UR7)Support by funds from Chemistry Department,Wright State University,College of Science and Mathematics for the purchase of the X-ray instrument is greatly acknowledged.The authors would like to acknowledge Dr Grossie,Wright State University and Dr Fratini,University of Dayton for help with low temperature single crystal X-ray diffraction measurements.S.S.acknowledges the donors of the American Chemical Society Petroleum Research Fund(PRF-58954-UNI5)and the National Science Foundation(Award#1904825)for support of this research.
文摘A series of five coordinated iron bis(dithiolene)complexes[Fe(NHC)(S_(2)C_(2)R_(2))_(2)](R=C_(6)H_(5)or C_(6)H_(4)-p-OCH_(3))containing N-heterocyclic carbene(NHC)(NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene or 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene)were isolated in high yield(84–92%).The iron complexes were characterized by NMR spectroscopy and confirmed by single crystal X-ray diffraction studies.
基金support of the Spanish Ministerio de Economía y Competitividad(grants PRE2019-088511,and PID2019-107006GB-C22)Generalitat Valenciana(grant CIAICO/2021/122)Universitat Jaume I(grants UJI-B2019-30,UJI-B2021-29 and UJI-B2022-56)is gratefully acknowledged.
文摘Imidazolyl amino cuboidal Mo_(3)(μ_(3)-S)(μ-S)_(3)clusters have been investigated as catalysts for the semihydrogenation of alkynes.For that purpose,three new air-stable cluster salts[Mo_(3)S_(4)Cl_(3)(ImNH_(2))_(3)]BF_(4)([1]BF_(4)),[Mo_(3)S_(4)Cl_(3)(ImNH(CH_(3)))_(3)]BF_(4)([2]BF_(4))and[Mo_(3)S_(4)Cl_(3)(ImN(CH_(3))_(2))_(3)]BF_(4)([3]BF_(4))have been isolated in moderate to high yields and fully characterized.Crystal structures of complexes[1]PF6 and[2]Cl confirm the formation of a single isomer in which the nitrogen atoms of the three imidazolyl groups of the ligands are located trans to the capping sulfur atom which leaves the three bridging sulfur centers on one side of the trimetallic plane while the amino groups lie on the opposite side.Kinetic studies show that the cluster bridging sulfurs react with diphenylacetylene(dpa)in a reversible equilibrium to form the corresponding dithiolene adduct.Formation of this adduct is postulated as the first step in the catalytic semihydrogenation of alkynes mediated by molybdenum sulfides.These complexes catalyze the(Z)-selective semihydrogenation of diphenylacetylene(dpa)under hydrogen in the absence of any additives.The catalytic activity lowers sequentially upon replacement of the hydrogen atoms of the N-H_(2)moiety in 1+without reaching inhibition.Mechanistic experiments support a sulfur centered mechanism without participation of the amino groups.Different diphenylacetylene derivatives are selectively hydrogenated using complex 1+to their corresponding Z-alkenes in excellent yields.Extension of this protocol to 3,7,11,15-tetramethylhexadec-1-yn-3-ol,an essential intermediate for the production of vitamin E,affords the semihydrogenation product in very good yield.
基金Project supported by grants for key research project in climbing program from the State Science and Technology Commission,and the National Nature Science Foundation of China.
文摘The reaction of CuCl2-2H2O or NiCl2.6H2O with K2(C5H6S4) [potassium salt of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]- or [Ni(C5H6S4)2]- as the tetrabutylammonium salt. Both complexes show characteristic IR and UV-Vis absorptions of transition metal dithiolenes. Cyclic voltammograms contain two waves indicating a two step electrochemical procedure [M(C5H6S4)2]0 = [M(C5H6S4)2]1-= [M(C5H6S4)2]2-. Single crystal structure study has been carried out on the nickel complex. Crystal of [Bu4N][Ni(C5H6S4)2] belongs to monoclinic space group P21/c with a=17.576(5), 6=10.883(2), c=17.773(4) A,B=91.07(2)0, Z=4, and o(calcd.)=1.348 g/cm3. Final result is R=0.059 for 2959 reflections. The NiS4 core exhibits square planar coordination with average Ni-S bond length of 2.134(5) A. There are not anion pairs in crystal. The anions stack along a and c axes while the cations intercalate in them. The nearest S-S contact is 4.429 A. The solid powder ESR spectrum of the nickel complex shows three broadening signals at g1=2.097, g2=2.042, g3=2.022. Magnetic susceptibility data for [Bu4N][Ni(CgH6S4)2] reveal enhanced anti-ferromagnetic interaction.
