A molecular-orbital model supported by energy-optimized MNDO calculations is presented for the substituent effects on the rates of the 1,5-sigmatropic reaction of cyclopentadienylborane compounds. The η2-structure represents the transition state and the σ-structure the ground state. The degenerate rearrangement is retarded with electron-donating ligands (e.g. amino-groups) at the boron atom and/or electron-withdrawing substituents at the C5H5 unit. Electron-donating substituents at the C5H5 unit facilitate the reaction. In the transition-state geometry, inversion over retention is favoured at the boron atom.
{"title":"THE 1,5-SIGMATROPIC SHIFT OF A BR2 UNIT (R = H, F, OH, NH2, CL, OR SH) OVER A CYCLOPENTADIENE SYSTEM","authors":"W. Schoeller","doi":"10.1039/DT9840002233","DOIUrl":"https://doi.org/10.1039/DT9840002233","url":null,"abstract":"A molecular-orbital model supported by energy-optimized MNDO calculations is presented for the substituent effects on the rates of the 1,5-sigmatropic reaction of cyclopentadienylborane compounds. The η2-structure represents the transition state and the σ-structure the ground state. The degenerate rearrangement is retarded with electron-donating ligands (e.g. amino-groups) at the boron atom and/or electron-withdrawing substituents at the C5H5 unit. Electron-donating substituents at the C5H5 unit facilitate the reaction. In the transition-state geometry, inversion over retention is favoured at the boron atom.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73845298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ternary oxides were converted to ternary sulfides by a metathesis reaction with a sulfur source such as diyttrium trisulfide. Reactions took place between two physically separated solid reactants under vacuum in a sealed silica tube. Preparation of the alkali-metal niobium disulfides ANbS2(A = Li, Na, K, Rb or Cs) has been attempted with isolation of quality crystals of the materials LixNbS2[a= 3.3412(2) and c= 12.876(1)A] and Na0.41NbS2[a= 3.3424(8) and c= 14.664(4)A] in the space group P63/mmc. Also considered has been the metathesis reaction of sodium metavanadate, alkaline-earth metal titanates and selected Group 6 ternary oxides with diyttrium trisulfide. The mechanism of these matathesis reactions has been studied, and in the course of these investigations the reduced hexagonal LiNbO2[a= 2.9070(6) and c= 10.457(3)A] was characterised. Formation of binary nitrides and carbides has been possible by replacing the sulfur source, Y2S3, with a source of nitrogen (e.g. YN) or carbon (e.g. TiC).
{"title":"A novel reaction between physically separated solid reactants","authors":"J. Gareh, M. G. Barker, M. Begley, A. Batsanov","doi":"10.1039/DT9950003825","DOIUrl":"https://doi.org/10.1039/DT9950003825","url":null,"abstract":"Ternary oxides were converted to ternary sulfides by a metathesis reaction with a sulfur source such as diyttrium trisulfide. Reactions took place between two physically separated solid reactants under vacuum in a sealed silica tube. Preparation of the alkali-metal niobium disulfides ANbS2(A = Li, Na, K, Rb or Cs) has been attempted with isolation of quality crystals of the materials LixNbS2[a= 3.3412(2) and c= 12.876(1)A] and Na0.41NbS2[a= 3.3424(8) and c= 14.664(4)A] in the space group P63/mmc. Also considered has been the metathesis reaction of sodium metavanadate, alkaline-earth metal titanates and selected Group 6 ternary oxides with diyttrium trisulfide. The mechanism of these matathesis reactions has been studied, and in the course of these investigations the reduced hexagonal LiNbO2[a= 2.9070(6) and c= 10.457(3)A] was characterised. Formation of binary nitrides and carbides has been possible by replacing the sulfur source, Y2S3, with a source of nitrogen (e.g. YN) or carbon (e.g. TiC).","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2010-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85613658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Brničević, P. Planinić, R. Mccarley, S. Antolić, M. Luić, B. Kojić-Prodić
Conditions have been established for the preparation of three different hydrated chloroniobium cluster hydroxide compounds from alkaline solutions: triclinic [Nb6Cl12(OH)2(H2O)4]·4H2O 1 and two cubic compounds whose structures are uncertain with regard to the co-ordination of OH– ions, Nb6Cl12(OH)2(H2O)142 and Nb6Cl12(H2O)14(OMe)23. Based upon structural data 2 and 3 may contain either the cation [Nb6Cl12(H2O)6]2+ or the neutral cluster [Nb6Cl12(OH)2(H2O)4] containing hydroxo ligands. In 1 distinct distances of 2.147(5) for Nb–OH, and 2.250(5) and 2.289(5)A for Nb–OH2 were found. In 2 and 3 only distances of 2.19(1) and 2.193(7)A, respectively, were found for the Nb–O bonds of co-ordinated water (or hydroxide-water averaged). Compound 1 is triclinic, space group P1, a= 8.930(3), b= 9.195(2), c= 9.118(1)A, α= 104.37(2), β= 99.51(2) and γ= 116.99(2)°, U= 611.9(3)A3, Z= 1, R= 1, R= 0.036. Compound 2 is cubic, space group Fm3m, a= 14.59(2)A, U= 3105.7(1)A3, Z= 4, R= 0.028. Compound 3 is also cubic, space group Fm3m, a= 14.627(1)A, U= 3129.3(1)A3, Z= 4, R= 0.031. IR spectra of 1 show strong O–H and Nb–O stretching bands that reflect the presence of co-ordinated OH– groups. In 2 and 3 the IR spectra are less definitive about possible co-ordination of hydroxide.
{"title":"Synthesis and structural characterization of three new compounds containing [Nb6Cl12]2+ units as hydrated hydroxides","authors":"N. Brničević, P. Planinić, R. Mccarley, S. Antolić, M. Luić, B. Kojić-Prodić","doi":"10.1039/DT9950001441","DOIUrl":"https://doi.org/10.1039/DT9950001441","url":null,"abstract":"Conditions have been established for the preparation of three different hydrated chloroniobium cluster hydroxide compounds from alkaline solutions: triclinic [Nb6Cl12(OH)2(H2O)4]·4H2O 1 and two cubic compounds whose structures are uncertain with regard to the co-ordination of OH– ions, Nb6Cl12(OH)2(H2O)142 and Nb6Cl12(H2O)14(OMe)23. Based upon structural data 2 and 3 may contain either the cation [Nb6Cl12(H2O)6]2+ or the neutral cluster [Nb6Cl12(OH)2(H2O)4] containing hydroxo ligands. In 1 distinct distances of 2.147(5) for Nb–OH, and 2.250(5) and 2.289(5)A for Nb–OH2 were found. In 2 and 3 only distances of 2.19(1) and 2.193(7)A, respectively, were found for the Nb–O bonds of co-ordinated water (or hydroxide-water averaged). Compound 1 is triclinic, space group P1, a= 8.930(3), b= 9.195(2), c= 9.118(1)A, α= 104.37(2), β= 99.51(2) and γ= 116.99(2)°, U= 611.9(3)A3, Z= 1, R= 1, R= 0.036. Compound 2 is cubic, space group Fm3m, a= 14.59(2)A, U= 3105.7(1)A3, Z= 4, R= 0.028. Compound 3 is also cubic, space group Fm3m, a= 14.627(1)A, U= 3129.3(1)A3, Z= 4, R= 0.031. IR spectra of 1 show strong O–H and Nb–O stretching bands that reflect the presence of co-ordinated OH– groups. In 2 and 3 the IR spectra are less definitive about possible co-ordination of hydroxide.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81820610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jang Sub Kim, Ayusman Sen, I. Guzei, L. Liable-Sands, A. Rheingold
Bimetallic palladium(II) methyl complexes, [Pd(dppmpH)(CH3)(μ-Cl)]2 (1) and [Pd(dippmpH)(CH3)(μ-Cl)]2 (2) were synthesized by the reaction of (COD)Pd(CH3)(Cl) (COD = 1,5-cyclooctadiene) with the new functional phosphine ligands 2-diphenylphosphino-4-methylphenol (dppmpH) and 2-diisopropylphosphino-4-methylphenol (dippmpH). The homolytic cleavage of the CH3–Pd bond was found to occur when complexes 1 and 2 were heated or photolyzed to form a methyl radical and the corresponding oxygen-bridged bimetallic palladium(II) complexes, [Pd(dppmp)(Cl)]2 (3) and [Pd(dippmp)(Cl)]2 (4), respectively. The molecular structures of complexes 1, 3 and 4 were determined by single-crystal X-ray diffraction. Reaction of small molecules, such as CO, SO2 and CH2CH2, with complexes 1 and 2 was observed and characterized by IR, 1H, 13C and 31P{1H} NMR spectroscopy.
{"title":"Synthesis and reactivity of bimetallic palladium(II) methyl complexes with new functional phosphine ligands","authors":"Jang Sub Kim, Ayusman Sen, I. Guzei, L. Liable-Sands, A. Rheingold","doi":"10.1039/B208060P","DOIUrl":"https://doi.org/10.1039/B208060P","url":null,"abstract":"Bimetallic palladium(II) methyl complexes, [Pd(dppmpH)(CH3)(μ-Cl)]2 \u0000(1) and [Pd(dippmpH)(CH3)(μ-Cl)]2 \u0000(2) were synthesized by the reaction of (COD)Pd(CH3)(Cl) \u0000(COD = 1,5-cyclooctadiene) with the new functional phosphine ligands 2-diphenylphosphino-4-methylphenol (dppmpH) and 2-diisopropylphosphino-4-methylphenol (dippmpH). The homolytic cleavage of the CH3–Pd bond was found to occur when complexes 1 and 2 were heated or photolyzed to form a methyl radical and the corresponding oxygen-bridged bimetallic palladium(II) complexes, [Pd(dppmp)(Cl)]2 \u0000(3) and [Pd(dippmp)(Cl)]2 \u0000(4), respectively. The molecular structures of complexes 1, 3 and 4 were determined by single-crystal X-ray diffraction. Reaction of small molecules, such as CO, SO2 and CH2CH2, with complexes 1 and 2 was observed and characterized by IR, 1H, 13C and 31P{1H} NMR spectroscopy.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74659109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new polythiogallate, CsGaS3, has been synthesized using molten flux of caesium polysulfide, and structurally characterized, by single crystal X-ray diffraction techniques, as possessing one-dimensional GaS3− chains, built from GaS4 tetrahedra. Cs+ ions undergo facile ion-exchange, at room temperature, with Rb+, NH4+, Me4N+ and alkaline earth and a few divalent first row transition metal ions in aqueous solution. AGaS3 (A = Cs, Rb, NH4, Me4N) compounds are, as determined from their diffuse reflectance spectra, insulators.
利用多硫化铯熔剂合成了一种新的聚没食子酸盐CsGaS3，并通过单晶x射线衍射技术对其结构进行了表征，发现其具有由GaS4四面体构建的一维GaS3−链。Cs+离子在室温下与水溶液中的Rb+、NH4+、Me4N+、碱土和少数二价第一排过渡金属离子进行易交换。根据其漫反射光谱测定，AGaS3 (A = Cs, Rb, NH4, Me4N)化合物是绝缘体。
{"title":"Molten flux synthesis, single crystal X-ray structure and ion-exchange properties of the first polythiogallate, CsGaS3","authors":"M. Devi, K. Vidyasagar","doi":"10.1039/B207741H","DOIUrl":"https://doi.org/10.1039/B207741H","url":null,"abstract":"A new polythiogallate, CsGaS3, has been synthesized using molten flux of caesium polysulfide, and structurally characterized, by single crystal X-ray diffraction techniques, as possessing one-dimensional GaS3− chains, built from GaS4 tetrahedra. Cs+ ions undergo facile ion-exchange, at room temperature, with Rb+, NH4+, Me4N+ and alkaline earth and a few divalent first row transition metal ions in aqueous solution. AGaS3 \u0000(A = Cs, Rb, NH4, Me4N) compounds are, as determined from their diffuse reflectance spectra, insulators.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75418856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Six palladium and one platinum compound containing dimeric dinuclear cations of the type [M2(a–a)2(µ-7tpO-N3,N4)2]2+ are presented, a–a representing a bidentate chelating amine and 7tpO− being the anionic form of the ligand 4,7-dihydro-7-oxo[1,2,4]triazolo[1,5-a]pyrimidine, which bridges the metal atoms through its nitrogen atoms in positions 3 and 4. Two linkage isomers are possible for such complexes, so called head–head and head–tail. According to 1H- and 195Pt-NMR data, both isomers are present in dmso-d6 solution and display analogous stability. An exhaustive assignment of the 1H signals has been made. The crystal structure of three of these compounds has been determined by single-crystal X-ray diffraction. For two of them, those with bispyrimidine as auxiliary ligand, the head–head and head–tail isomers coexist even in the solid state, both being present in the same crystal in a disordered scheme. This situation is explained by the almost symmetric external shape of the bridging ligand, which is expected to interact with neighbouring species in a similar way even if rotated 180 degrees.
六种钯和一种铂化合物含有二聚双核阳离子[M2(a -a)2(µ-7tpO-N3,N4)2]2+， a -a代表双齿螯合胺，7tpO−是配体4,7-二氢-7-氧[1,2,4]三唑[1,5-a]嘧啶的阴离子形式，它通过3和4位的氮原子桥接金属原子。这种配合物可能有两种键同分异构体，称为正-正和正-反。根据1H-和195Pt-NMR数据，这两种异构体都存在于dmso-d6溶液中，并表现出类似的稳定性。对1H信号进行了详尽的分配。其中三种化合物的晶体结构已通过单晶x射线衍射测定。对于其中的两种，即那些以双嘧啶作为辅助配体的，即使在固体状态下，头-头和头-尾异构体也是共存的，它们都以无序的方式存在于同一个晶体中。这种情况可以用桥接配体几乎对称的外部形状来解释，即使旋转180度，桥接配体也可以以类似的方式与邻近的物种相互作用。
{"title":"Solution and solid state coexistence of head–head and head–tail isomers in dimeric Pd(II) and Pt(II) complexes of the type [M2(a–a)2(µ-L-N3N4)2]2+ with a bridging triazolopyrimidine ligand and chelating bidentate diamines","authors":"M. Haj, M. Quirós, J. M. Salas","doi":"10.1039/B207263G","DOIUrl":"https://doi.org/10.1039/B207263G","url":null,"abstract":"Six palladium and one platinum compound containing dimeric dinuclear cations of the type [M2(a–a)2(µ-7tpO-N3,N4)2]2+ are presented, a–a representing a bidentate chelating amine and 7tpO− being the anionic form of the ligand 4,7-dihydro-7-oxo[1,2,4]triazolo[1,5-a]pyrimidine, which bridges the metal atoms through its nitrogen atoms in positions 3 and 4. Two linkage isomers are possible for such complexes, so called head–head and head–tail. According to 1H- and 195Pt-NMR data, both isomers are present in dmso-d6 solution and display analogous stability. An exhaustive assignment of the 1H signals has been made. The crystal structure of three of these compounds has been determined by single-crystal X-ray diffraction. For two of them, those with bispyrimidine as auxiliary ligand, the head–head and head–tail isomers coexist even in the solid state, both being present in the same crystal in a disordered scheme. This situation is explained by the almost symmetric external shape of the bridging ligand, which is expected to interact with neighbouring species in a similar way even if rotated 180 degrees.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89855308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A 103Rh, 31P and 13C NMR study of [Rh4(CO)6(μ-PPh2)4] in CD2Cl2 indicates that the strongly bonded, bridging, anionic ligand PPh2− takes part in the site exchange of the carbonyl ligands and is actually mobile about the metallic surface of this cluster compound.
{"title":"Intramolecular dynamics of [Rh4(CO)6(μ-PPh2)4] in solution","authors":"E. Gullo, S. Detti, G. Laurenczy, R. Roulet","doi":"10.1039/B208318C","DOIUrl":"https://doi.org/10.1039/B208318C","url":null,"abstract":"A 103Rh, 31P and 13C NMR study of [Rh4(CO)6(μ-PPh2)4] in CD2Cl2 indicates that the strongly bonded, bridging, anionic ligand PPh2− takes part in the site exchange of the carbonyl ligands and is actually mobile about the metallic surface of this cluster compound.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88489617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Andrews, G. Deacon, W. R. Jackson, Melissa Maguire, Natalie M. Scott, B. Skelton, Allan H. White
The thermally induced solvent-free reactions of Ph3Bi with a series of thiols and carboxylic acids (2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-ethoxybenzoic acid, 1-mercapto-2-propanol and salicylic acid) in the ratio 1 ∶ 3 have been investigated and shown to produce the fully substituted bismuth thiolates and benzoates in good yields and purity. Thermogravimetric analysis and differential scanning calorimetry have been used to study the profiles of those reactions involving two solid components and indicate that the reactions occur with the onset of the melting of Ph3Bi. The two products from the reactions with 2-ethoxybenzoic acid and 1-mercapto-2-propanol have been characterised by single crystal X-ray diffraction and shown to be dimeric, [(2-EtOC6H5CO2)3Bi]2, 1, and polymeric, [{(CH3CH(OH)CH2S)(CH3CH(O)CH2S)}Bi]∞, 2, respectively. Compound 1 crystallises as centrosymmetric dimers with the two Bi centres bridged by carboxylate O atoms with possible polymerisation prevented by the further interaction of one of the ethoxy groups with each metal centre. In contrast compound 2 is made up of monomeric units, containing both a mono-anion and a dianion with quasi polymeric linkages arising from bridging S atoms accompanying OH⋯O hydrogen bonding interactions between the two ligand species.
{"title":"Solvent-free synthesis of bismuth thiolates and carboxylates","authors":"P. Andrews, G. Deacon, W. R. Jackson, Melissa Maguire, Natalie M. Scott, B. Skelton, Allan H. White","doi":"10.1039/B209347B","DOIUrl":"https://doi.org/10.1039/B209347B","url":null,"abstract":"The thermally induced solvent-free reactions of Ph3Bi with a series of thiols and carboxylic acids (2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-ethoxybenzoic acid, 1-mercapto-2-propanol and salicylic acid) in the ratio 1 ∶ 3 have been investigated and shown to produce the fully substituted bismuth thiolates and benzoates in good yields and purity. Thermogravimetric analysis and differential scanning calorimetry have been used to study the profiles of those reactions involving two solid components and indicate that the reactions occur with the onset of the melting of Ph3Bi. The two products from the reactions with 2-ethoxybenzoic acid and 1-mercapto-2-propanol have been characterised by single crystal X-ray diffraction and shown to be dimeric, [(2-EtOC6H5CO2)3Bi]2, 1, and polymeric, [{(CH3CH(OH)CH2S)(CH3CH(O)CH2S)}Bi]∞, 2, respectively. Compound 1 crystallises as centrosymmetric dimers with the two Bi centres bridged by carboxylate O atoms with possible polymerisation prevented by the further interaction of one of the ethoxy groups with each metal centre. In contrast compound 2 is made up of monomeric units, containing both a mono-anion and a dianion with quasi polymeric linkages arising from bridging S atoms accompanying OH⋯O hydrogen bonding interactions between the two ligand species.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85428240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Fondo, A. M. García-Deibe, M. R. Bermejo, J. Sanmartín, A. Llamas-Saiz
The electrochemical reaction of zinc and 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine (H3L1) in acetonitrile in air yields the tetranuclear zinc complex [(Zn2L)2(CO3)]·4H2O, which crystallises with different solvent molecules in two different systems: [(Zn2L)2(CO3)]·4H2O·2CH3CN 1a (monoclinic, Pn) and [(Zn2L)2(CO3)]·4H2O 1b (triclinic, P). The electrochemical reaction under a nitrogen stream leads to the isolation of crystals of [(Zn2L)2(CO3)]·0·25H2O·2CH3CN 1c (monoclinic P21/c). All structures demonstrate the striking ability of this system to spontaneously fix carbon dioxide. The crystals solution reveal a µ4-η2:η1:η1 binding mode for the carbonate group in all cases, leading to a tetranuclear complex by self-assembly of dinuclear units. Chemical reaction of Zn(CH3COO)2·2H2O with H3L yields [Zn2L(CH3COO)]·2H2O. Its recrystallisation allows isolating [Zn2L(CH3COO)]·2H2O·CH3OH 2. Reaction of [Zn2L(CH3COO)]·2H2O with (CH3)4NOH·5H2O leads, again, to the tetranuclear carbonate compound.
{"title":"Spontaneous carbon dioxide fixation: a µ4-carbonate bridged tetranuclear zinc(II) complex of a heptadentate Schiff base","authors":"M. Fondo, A. M. García-Deibe, M. R. Bermejo, J. Sanmartín, A. Llamas-Saiz","doi":"10.1039/B209328F","DOIUrl":"https://doi.org/10.1039/B209328F","url":null,"abstract":"The electrochemical reaction of zinc and 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine (H3L1) in acetonitrile in air yields the tetranuclear zinc complex [(Zn2L)2(CO3)]·4H2O, which crystallises with different solvent molecules in two different systems: [(Zn2L)2(CO3)]·4H2O·2CH3CN 1a \u0000(monoclinic, Pn) and [(Zn2L)2(CO3)]·4H2O 1b \u0000(triclinic, P). The electrochemical reaction under a nitrogen stream leads to the isolation of crystals of [(Zn2L)2(CO3)]·0·25H2O·2CH3CN 1c \u0000(monoclinic P21/c). All structures demonstrate the striking ability of this system to spontaneously fix carbon dioxide. The crystals solution reveal a µ4-η2:η1:η1 binding mode for the carbonate group in all cases, leading to a tetranuclear complex by self-assembly of dinuclear units. Chemical reaction of Zn(CH3COO)2·2H2O with H3L yields [Zn2L(CH3COO)]·2H2O. Its recrystallisation allows isolating [Zn2L(CH3COO)]·2H2O·CH3OH 2. Reaction of [Zn2L(CH3COO)]·2H2O with (CH3)4NOH·5H2O leads, again, to the tetranuclear carbonate compound.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87466913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Sellin, Ingrid Bach, J. M. Webster, F. Montilla, Vitor Rosa, T. Avilés, M. Poliakoff, D. Cole-Hamilton
Rhodium complexes modified by simple trialkylphosphines can be used to carry out homogeneous hydroformylation in supercritical carbon dioxide (scCO2). The catalyst derived from PEt3 is more active and slightly more selective for the linear products in scCO2 than in toluene, and under the same reaction conditions [100°C, 40 bar of CO/H2 (1∶1)] P(OPri)3 is also an effective ligand giving good catalyst solubility and activity. Other ligands such as PPh3, POct3, PCy3, and P(4-C6H4But)3 are less effective because of the low solubility of their rhodium complexes in scCO2. P(4-C6H4SiMe3)nPh3−n (n = 3 or 1) and P(OPh)3 impart activity despite their complexes only being poorly soluble in scCO2. Under subcritical conditions, using PEt3 as the ligand, C7-alcohols from hydrogenation of the first formed aldehydes are the main products whilst above a total pressure of 200 bar, where the solution remains supercritical (monophasic) throughout the reaction, aldehydes are obtained with 97% selectivity. High pressure IR studies in scCO2 using PEt3 as the ligand are reported.
简单三烷基膦修饰的铑配合物可在超临界二氧化碳(scCO2)中进行均相氢甲酰化反应。PEt3衍生的催化剂在scCO2中比在甲苯中具有更高的活性和略高的选择性，在相同的反应条件下[100°C, 40 bar CO/H2(1∶1)]P(OPri)3也是一种有效的配体，具有良好的催化剂溶解度和活性。其他配体如PPh3、POct3、PCy3和P(4-C6H4But)3的效果较差，因为它们的铑配合物在scCO2中的溶解度较低。尽管P(4-C6H4SiMe3)nPh3−n (n = 3或1)和P(OPh)3配合物在scCO2中难溶，但它们仍具有活性。在亚临界条件下，以PEt3为配体，由第一个形成的醛加氢生成的c7醇是主要产物，而在总压力为200 bar以上，溶液在整个反应过程中保持超临界(单相)，醛的选择性为97%。本文报道了以PEt3为配体在scCO2中的高压红外研究。
{"title":"Hydroformylation of alkenes in supercritical carbon dioxide catalysed by rhodium trialkylphosphine complexes","authors":"M. Sellin, Ingrid Bach, J. M. Webster, F. Montilla, Vitor Rosa, T. Avilés, M. Poliakoff, D. Cole-Hamilton","doi":"10.1039/B207747G","DOIUrl":"https://doi.org/10.1039/B207747G","url":null,"abstract":"Rhodium complexes modified by simple trialkylphosphines can be used to carry out homogeneous hydroformylation in supercritical carbon dioxide (scCO2). The catalyst derived from PEt3 is more active and slightly more selective for the linear products in scCO2 than in toluene, and under the same reaction conditions [100°C, 40 bar of CO/H2 \u0000(1∶1)] P(OPri)3 is also an effective ligand giving good catalyst solubility and activity. Other ligands such as PPh3, POct3, PCy3, and P(4-C6H4But)3 are less effective because of the low solubility of their rhodium complexes in scCO2. P(4-C6H4SiMe3)nPh3−n (n = 3 or 1) and P(OPh)3 impart activity despite their complexes only being poorly soluble in scCO2. Under subcritical conditions, using PEt3 as the ligand, C7-alcohols from hydrogenation of the first formed aldehydes are the main products whilst above a total pressure of 200 bar, where the solution remains supercritical (monophasic) throughout the reaction, aldehydes are obtained with 97% selectivity. High pressure IR studies in scCO2 using PEt3 as the ligand are reported.","PeriodicalId":17317,"journal":{"name":"Journal of The Chemical Society-dalton Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2002-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88481842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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