Pablo Espinet - Academia.edu (original) (raw)
Papers by Pablo Espinet
Coordination Chemistry Reviews, 2008
The applications of 19F NMR in the study of a number of problems in organometallic chemistry are ... more The applications of 19F NMR in the study of a number of problems in organometallic chemistry are illustrated with relevant cases, paying special attention to the case of molecules containing fluorinated aryls. These are used as reporter groups of molecular symmetry, fluxional processes, and chemical changes, and help in the study of many fundamental organometallic processes.
Rod-like gold(I) complexes [Au(C 6 F 4 OC m H 2m'1 )(C Å/NC 6 H 4 O(O)CC 6 H 4 OC n H 2n'1 )] [m ... more Rod-like gold(I) complexes [Au(C 6 F 4 OC m H 2m'1 )(C Å/NC 6 H 4 O(O)CC 6 H 4 OC n H 2n'1 )] [m 0/4, 8; n 0/4, 6, 8, 10] have been prepared and their liquid crystal behavior studied. All the tetrafluorophenylgold(I) derivatives described are liquid crystals and their thermal stability is high, even in the isotropic state. The variation in thermal properties of tetrafluorophenylgold(I) complexes is very regular. When a short alkoxy chain is placed in the tetrafluorophenyl group (m 0/4), both smectic A and nematic phases are observed for shorter alkoxy substituents in the isocyanide ligand (n 0/4, 6). For longer chain-lengths (n 0/8, 10), only smectic A phases are observed. When the alkoxy substituent in the tetrafluorophenyl group is longer (m 0/8), both SmA and SmC phases are obtained, irrespective of the chain-lengths of the isocyanide ligand. #
![Research paper thumbnail of [Pd(Fmes)I{NMe2(CH2-o-C6H4-I)-N,I}], a palladium(II) complex with I− and organic iodide as trans ligands](https://attachments.academia-assets.com/42664263/thumbnails/1.jpg)
](The treatment of [Pd(dmba)(Fmes)(OH 2 )] with I 2 leads to the formation of [Pd(Fmes)I{NMe 2 (CH ... more The treatment of [Pd(dmba)(Fmes)(OH 2 )] with I 2 leads to the formation of [Pd(Fmes)I{NMe 2 (CH 2 -o -C 6 H 4 -I)-N,I}]. The X-ray structure shows that a new halocarbon ligand, (2-iodobenzyl)dimethylamine has been formed and is acting as N Á/I chelate. The two different types of iodine, one iodide ligand and one organic iodide coordinated to Pd, are mutually trans and display essentially identical Pd Á/I distances. #
New 1,1-alkoxy, aryl substituted palladium g 3 -allyls [Pd(l-Br){g 3 -C(C 6 F 5 )(OMe)CHR 1 CHR 2... more New 1,1-alkoxy, aryl substituted palladium g 3 -allyls [Pd(l-Br){g 3 -C(C 6 F 5 )(OMe)CHR 1 CHR 2 }] 2 can be synthesized from [W(CO) 5 {C(OMe)CHR 1 @CHR 2 }] and a palladium perfluoroaryl complex. The allyls are formed by transmetalation of the carbene fragment followed by migratory insertion of C 6 F 5 to the putative and highly reactive Pd carbene complex. This reaction pathway predominates in all cases, but insertion of the double bond of the tungsten alkoxyvinylcarbenes into the Pd-C 6 F 5 bond leads to secondary products, namely C 6 F 5 (OMe)C@CR 1 CH(C 6 F 5 )R 2 .
Halide abstraction from [Pd(l-Cl)(Fmes)(NCMe)] 2 (Fmes = 2,4,6-tris(trifluoromethyl)phenyl or non... more Halide abstraction from [Pd(l-Cl)(Fmes)(NCMe)] 2 (Fmes = 2,4,6-tris(trifluoromethyl)phenyl or nonafluoromesityl) with TlBF 4 in CH 2 Cl 2 /MeCN gives [Pd(Fmes)(NCMe) 3 ]BF 4 , which reacts with monodentate ligands to give the monosubstituted products trans-[Pd(Fmes)L(NCMe) 2 ]BF 4 (L = PPh 3 , P(o-Tol) 3 , 3,5-lut, 2,4-lut, 2,6-lut; lut = dimethylpyridine), the disubstituted products trans-[Pd(Fmes)(NCMe)(PPh 3 ) 2 ]BF 4 , cis-[Pd(Fmes)(3,5-lut) 2 (NCMe)]BF 4 , or the trisubstituted products [Pd(Fmes)L 3 ]BF 4 (L = CN t Bu, PHPh 2 , 3,5-lut, 2,4-lut). Similar reactions using bidentate chelating ligands give [Pd(Fmes)(L-L)(NCMe)]BF 4 (L-L = bipy, tmeda, dppe, OPPhPy 2 -N,N 0 , (OH)(CH 3 )CPy 2 -N,N 0 ). The complexes trans-[Pd(Fmes)L 2 (NCMe)]BF 4 (L = PPh 3 , tht) (tht = tetrahydrothiophene) and [Pd(Fmes)(L-L)(NCMe)]BF 4 (L-L = bipy, tmeda) were obtained by halide extraction with TlBF 4 in CH 2 Cl 2 /MeCN from the corresponding neutral halogeno complexes trans-[Pd(Fmes)ClL 2 ] or [Pd(Fmes)Cl(L-L)]
Journal of The American Chemical Society, 1992
... in the Solid State: Covalent Soaps Maria J. Baena,+ Pablo Espinet,*,+ M. Carmen Lequerica,t... more ... in the Solid State: Covalent Soaps Maria J. Baena,+ Pablo Espinet,*,+ M. Carmen Lequerica,t and Anne Marie Levelutl ... Muter. 1990, 2, 748. (1 1) Palm, G. M.; Margomenou-Leonidopoulou, G.; Anastassopoulou, J. D.; Papaconstantinou, E. Mol. Cryst. Liq. Cryst. 1988, ...
Chemistry of Materials, 1998
Palladium and platinum (II) complexes [MX2 {C⋮ NC6H2 (3, 4, 5-OC n H2 n+ 1) 3} 2](X= Cl, Br, I; n... more Palladium and platinum (II) complexes [MX2 {C⋮ NC6H2 (3, 4, 5-OC n H2 n+ 1) 3} 2](X= Cl, Br, I; n= 4, 6, 8, 10, 12) have been prepared. The free isocyanides are not liquid crystals, but most of their complexes [MX2 {C⋮ NC6H2 (3, 4, 5-OC n H2 n+ 1) 3} 2](M= Pd, Pt; X= Cl, Br ...
Tetrahedron Letters, 2001
The complexes [Rh(diene)(L-L′)](BF4), and [RhCl(CO)(L-L′)] (diene=COD 1,5-cyclooctadiene; L-L′=P(... more The complexes [Rh(diene)(L-L′)](BF4), and [RhCl(CO)(L-L′)] (diene=COD 1,5-cyclooctadiene; L-L′=P(bzN)Ph2, P(bzN)2Ph, P(bzN)3, PePy, or PePy2, bzN=2-(dimethylaminomethyl)phenyl, PePyn=P(CH2CH2Py)nPh3−n; Py=2-pyridyl; n=1,2) are poor catalysts for the hydrosilylation of 1-hexyne, but excellent catalysts for the silylformylation of 1-hexyne in tetrahydrofurane at atmospheric pressure and room temperature.
Journal of The American Chemical Society, 2007
Organometallics, 1996
ABSTRACT Complexes containing one or two Fmes ligands (Fmes = 2,4,6-tris(trifluoromethyl)phenyl =... more ABSTRACT Complexes containing one or two Fmes ligands (Fmes = 2,4,6-tris(trifluoromethyl)phenyl = nonafluoromesityl) either trans or cis are obtained by treating palladium(II) chloro complexes with Li(Fmes): trans-[PdCl2L2] (L = tetrahydrothiophene (tht), PPh3) lead to trans-[Pd(Fmes)ClL2] (L = tht, PPh3) or trans-[Pd(Fmes)2L2] (L = tht); [PdCl2(L-L)] (L-L = 1,5-cyclooctadiene, 2,2‘-bipyridine) give [Pd(Fmes)Cl(L-L)] (L-L = COD, bipy) or [Pd(Fmes)2(bipy)]. The structures of two complexes containing two Fmes ligands in trans and cis arrangement, trans-[Pd(Fmes)2(tht)2] (2) and [Pd(Fmes)2(bipy)] (6), respectively, have been determined by X-ray diffraction. In spite of the severe steric congestion the complexes are four coordinated. Distortions due to the bulkiness of the ortho substituents and short Pd···F3C-ortho distances are observed. The high degree of steric crowding is also responsible for slow rotation around the Pd−P bonds in the complex trans-[Pd(Fmes)Cl(PPh3)2]. ΔG associated with this motion is 12.8 kcal mol-1, one of the highest values reported so far for rotation around M−PPh3 bonds. Complexes 2 and 6 are redox inactive by cyclic voltammetry in the range −1.8 to +1.8 V.
Journal of Organometallic Chemistry, 1998
High yield methods for the synthesis of cis-[MR2(COD)] (M=Pd, Pt; R=3,5-C6Cl2F3), cis-[MR2(THF)2]... more High yield methods for the synthesis of cis-[MR2(COD)] (M=Pd, Pt; R=3,5-C6Cl2F3), cis-[MR2(THF)2] (M=Pd; Pt), trans-[PdR2L2] (L=tht; SMe2), trans-[PtR2(SMe2)2], and [M2(μ-Cl)2R2L2] (M=Pd, L=NCPh, tht, SMe2; M=Pt, L=tht) are reported. These complexes are general precursors for the preparation of other complexes containing cis-MR2, trans-MR2 and MClR moieties in almost quantitative yields. Thus, by displacement of COD, THF, tht or SMe2 by other
Inorganic Chemistry, 1997
... Poly(2-pyridyl)phosphines, PPy n Ph 3 - n (n = 2, 3), and Their P-Substituted Derivatives as ... more ... Poly(2-pyridyl)phosphines, PPy n Ph 3 - n (n = 2, 3), and Their P-Substituted Derivatives as Tripodal Ligands in Molybdenum(0) Carbonyl Complexes. ... Juan A. Casares, Pablo Espinet,* Rosa Hernando, Gonzalo Iturbe, and Fernando Villafañe. ...
Chemical Communications, 2001
The main sequential intermediates involved in a real catalytic cycle of the Stille reaction (the ... more The main sequential intermediates involved in a real catalytic cycle of the Stille reaction (the coupling of ROTf with CH 2 NCHSnBu 3 catalyzed by [PdR(OTf)(dppe)]; R = aryl) are observed and characterized unequivocally before the coupling product is released.
Journal of Materials Chemistry - J MATER CHEM, 1997
... Silverio Coco,a Pablo Espinet,*a José M. Martın-Alvareza and Anne-Marie Levelutb aDepartament... more ... Silverio Coco,a Pablo Espinet,*a José M. Martın-Alvareza and Anne-Marie Levelutb aDepartamento de Quımica Inorgánica, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid, Spain bL ... Found: C, 37.65; H, 3.97; N, 3.08%); DSC/°CK–K∞ 146.9 (2.1), K∞–S ...
Chemistry of Materials - CHEM MATER, 2004
... Beatriz Ballesteros, Silverio Coco, and Pablo Espinet*. ... weighing, mixing, and heating of ... more ... Beatriz Ballesteros, Silverio Coco, and Pablo Espinet*. ... weighing, mixing, and heating of the samples) and the effect of the heating rate in viscous materials, makes it advisable to give the transition temperatures in this paper an allowance of ±1 °C. X-ray diffraction experiments on ...
Organometallics, 2002
ABSTRACT The neutral palladium complex [Pd(C6F5)Br(NCMe)2] (1) was found to effect the polymeriza... more ABSTRACT The neutral palladium complex [Pd(C6F5)Br(NCMe)2] (1) was found to effect the polymerization of acrylates upon addition of 1 equiv of a monodentate phosphine or pyridine or an excess of halide. Methyl methacrylate was not polymerized, and furthermore, its addition stopped the progress of independently initiated methyl acrylate polymerization in the phosphine-based system. Addition of ethene also inhibited the polymerization of methyl acrylate. However, over 10 mol % incorporation of 1-hexene in the polymer was achieved when the latter was added together with methyl acrylate. The polymerizaion mechanism is discussed.
Organometallics, 1999
... N. Marta Catalina, Pablo Espinet,* and Rocío Redón. ... Abstract. Abstract Image. The behavio... more ... N. Marta Catalina, Pablo Espinet,* and Rocío Redón. ... Abstract. Abstract Image. The behavior of palladium C-bound enolates [Pd(CH 2 C(O)CR 3 )Cl(PPh 3 ) 2 ] (R = H, 1; R = Me, 2) and [Pd(CH 2 C(O)CR 3 )(PPh 3 ) 2 (NCMe)](BF 4 ) (R = H, 5; R = Me, 6) has been studied. ...
Organometallics, 2008
Neutral trans-[Pd(C 6 F 5 )XL 2 ] (X ) Cl, Br) and cationic trans-[Pd(C 6 F 5 )L 2 (NCMe)]BF 4 (L... more Neutral trans-[Pd(C 6 F 5 )XL 2 ] (X ) Cl, Br) and cationic trans-[Pd(C 6 F 5 )L 2 (NCMe)]BF 4 (L ) SbPh 3 , AsPh 3 , As(C 6 Cl 2 F 3 )Ph 2 , AsCyPh 2 , AsMePh 2 , PPh 3 ) complexes have been studied and tested for norbornene (NB) polymerization and copolymerization with 5-norbornene-2-carboxaldehyde (NB-CHO). The neutral complexes are almost inactive and produce only small amounts of oligomers, but the cationic complexes with arsines and stibines are very good for palladium-catalyzed norbornene polymerization. External coordinating molecules (e.g., ligands or monomers with O-donor groups) compete with the olefin function for the coordination sites on Pd and inhibit the reaction. In spite of this, copolymerization of norbornene and 5-norbornene-2-carboxaldehyde could be achieved, with lower yields and higher incorporations of the functionalized norbornene as the NB:NB-CHO ratio decreases. The complex with the fluorinated arsine AsPh 2 (C 6 Cl 2 F 3 ) is the most active catalyst and allows for easy spectroscopic study of the reacting systems by 19 F NMR. Calorimetry provides straightforward monitoring and detection of activation and deactivation processes in polymerization reactions that give insoluble products and cannot be followed by NMR spectroscopy.
Coordination Chemistry Reviews, 2008
The applications of 19F NMR in the study of a number of problems in organometallic chemistry are ... more The applications of 19F NMR in the study of a number of problems in organometallic chemistry are illustrated with relevant cases, paying special attention to the case of molecules containing fluorinated aryls. These are used as reporter groups of molecular symmetry, fluxional processes, and chemical changes, and help in the study of many fundamental organometallic processes.
Rod-like gold(I) complexes [Au(C 6 F 4 OC m H 2m'1 )(C Å/NC 6 H 4 O(O)CC 6 H 4 OC n H 2n'1 )] [m ... more Rod-like gold(I) complexes [Au(C 6 F 4 OC m H 2m'1 )(C Å/NC 6 H 4 O(O)CC 6 H 4 OC n H 2n'1 )] [m 0/4, 8; n 0/4, 6, 8, 10] have been prepared and their liquid crystal behavior studied. All the tetrafluorophenylgold(I) derivatives described are liquid crystals and their thermal stability is high, even in the isotropic state. The variation in thermal properties of tetrafluorophenylgold(I) complexes is very regular. When a short alkoxy chain is placed in the tetrafluorophenyl group (m 0/4), both smectic A and nematic phases are observed for shorter alkoxy substituents in the isocyanide ligand (n 0/4, 6). For longer chain-lengths (n 0/8, 10), only smectic A phases are observed. When the alkoxy substituent in the tetrafluorophenyl group is longer (m 0/8), both SmA and SmC phases are obtained, irrespective of the chain-lengths of the isocyanide ligand. #
The treatment of [Pd(dmba)(Fmes)(OH 2 )] with I 2 leads to the formation of [Pd(Fmes)I{NMe 2 (CH ... more The treatment of [Pd(dmba)(Fmes)(OH 2 )] with I 2 leads to the formation of [Pd(Fmes)I{NMe 2 (CH 2 -o -C 6 H 4 -I)-N,I}]. The X-ray structure shows that a new halocarbon ligand, (2-iodobenzyl)dimethylamine has been formed and is acting as N Á/I chelate. The two different types of iodine, one iodide ligand and one organic iodide coordinated to Pd, are mutually trans and display essentially identical Pd Á/I distances. #
New 1,1-alkoxy, aryl substituted palladium g 3 -allyls [Pd(l-Br){g 3 -C(C 6 F 5 )(OMe)CHR 1 CHR 2... more New 1,1-alkoxy, aryl substituted palladium g 3 -allyls [Pd(l-Br){g 3 -C(C 6 F 5 )(OMe)CHR 1 CHR 2 }] 2 can be synthesized from [W(CO) 5 {C(OMe)CHR 1 @CHR 2 }] and a palladium perfluoroaryl complex. The allyls are formed by transmetalation of the carbene fragment followed by migratory insertion of C 6 F 5 to the putative and highly reactive Pd carbene complex. This reaction pathway predominates in all cases, but insertion of the double bond of the tungsten alkoxyvinylcarbenes into the Pd-C 6 F 5 bond leads to secondary products, namely C 6 F 5 (OMe)C@CR 1 CH(C 6 F 5 )R 2 .
Halide abstraction from [Pd(l-Cl)(Fmes)(NCMe)] 2 (Fmes = 2,4,6-tris(trifluoromethyl)phenyl or non... more Halide abstraction from [Pd(l-Cl)(Fmes)(NCMe)] 2 (Fmes = 2,4,6-tris(trifluoromethyl)phenyl or nonafluoromesityl) with TlBF 4 in CH 2 Cl 2 /MeCN gives [Pd(Fmes)(NCMe) 3 ]BF 4 , which reacts with monodentate ligands to give the monosubstituted products trans-[Pd(Fmes)L(NCMe) 2 ]BF 4 (L = PPh 3 , P(o-Tol) 3 , 3,5-lut, 2,4-lut, 2,6-lut; lut = dimethylpyridine), the disubstituted products trans-[Pd(Fmes)(NCMe)(PPh 3 ) 2 ]BF 4 , cis-[Pd(Fmes)(3,5-lut) 2 (NCMe)]BF 4 , or the trisubstituted products [Pd(Fmes)L 3 ]BF 4 (L = CN t Bu, PHPh 2 , 3,5-lut, 2,4-lut). Similar reactions using bidentate chelating ligands give [Pd(Fmes)(L-L)(NCMe)]BF 4 (L-L = bipy, tmeda, dppe, OPPhPy 2 -N,N 0 , (OH)(CH 3 )CPy 2 -N,N 0 ). The complexes trans-[Pd(Fmes)L 2 (NCMe)]BF 4 (L = PPh 3 , tht) (tht = tetrahydrothiophene) and [Pd(Fmes)(L-L)(NCMe)]BF 4 (L-L = bipy, tmeda) were obtained by halide extraction with TlBF 4 in CH 2 Cl 2 /MeCN from the corresponding neutral halogeno complexes trans-[Pd(Fmes)ClL 2 ] or [Pd(Fmes)Cl(L-L)]
Journal of The American Chemical Society, 1992
... in the Solid State: Covalent Soaps Maria J. Baena,+ Pablo Espinet,*,+ M. Carmen Lequerica,t... more ... in the Solid State: Covalent Soaps Maria J. Baena,+ Pablo Espinet,*,+ M. Carmen Lequerica,t and Anne Marie Levelutl ... Muter. 1990, 2, 748. (1 1) Palm, G. M.; Margomenou-Leonidopoulou, G.; Anastassopoulou, J. D.; Papaconstantinou, E. Mol. Cryst. Liq. Cryst. 1988, ...
Chemistry of Materials, 1998
Palladium and platinum (II) complexes [MX2 {C⋮ NC6H2 (3, 4, 5-OC n H2 n+ 1) 3} 2](X= Cl, Br, I; n... more Palladium and platinum (II) complexes [MX2 {C⋮ NC6H2 (3, 4, 5-OC n H2 n+ 1) 3} 2](X= Cl, Br, I; n= 4, 6, 8, 10, 12) have been prepared. The free isocyanides are not liquid crystals, but most of their complexes [MX2 {C⋮ NC6H2 (3, 4, 5-OC n H2 n+ 1) 3} 2](M= Pd, Pt; X= Cl, Br ...
Tetrahedron Letters, 2001
The complexes [Rh(diene)(L-L′)](BF4), and [RhCl(CO)(L-L′)] (diene=COD 1,5-cyclooctadiene; L-L′=P(... more The complexes [Rh(diene)(L-L′)](BF4), and [RhCl(CO)(L-L′)] (diene=COD 1,5-cyclooctadiene; L-L′=P(bzN)Ph2, P(bzN)2Ph, P(bzN)3, PePy, or PePy2, bzN=2-(dimethylaminomethyl)phenyl, PePyn=P(CH2CH2Py)nPh3−n; Py=2-pyridyl; n=1,2) are poor catalysts for the hydrosilylation of 1-hexyne, but excellent catalysts for the silylformylation of 1-hexyne in tetrahydrofurane at atmospheric pressure and room temperature.
Journal of The American Chemical Society, 2007
Organometallics, 1996
ABSTRACT Complexes containing one or two Fmes ligands (Fmes = 2,4,6-tris(trifluoromethyl)phenyl =... more ABSTRACT Complexes containing one or two Fmes ligands (Fmes = 2,4,6-tris(trifluoromethyl)phenyl = nonafluoromesityl) either trans or cis are obtained by treating palladium(II) chloro complexes with Li(Fmes): trans-[PdCl2L2] (L = tetrahydrothiophene (tht), PPh3) lead to trans-[Pd(Fmes)ClL2] (L = tht, PPh3) or trans-[Pd(Fmes)2L2] (L = tht); [PdCl2(L-L)] (L-L = 1,5-cyclooctadiene, 2,2‘-bipyridine) give [Pd(Fmes)Cl(L-L)] (L-L = COD, bipy) or [Pd(Fmes)2(bipy)]. The structures of two complexes containing two Fmes ligands in trans and cis arrangement, trans-[Pd(Fmes)2(tht)2] (2) and [Pd(Fmes)2(bipy)] (6), respectively, have been determined by X-ray diffraction. In spite of the severe steric congestion the complexes are four coordinated. Distortions due to the bulkiness of the ortho substituents and short Pd···F3C-ortho distances are observed. The high degree of steric crowding is also responsible for slow rotation around the Pd−P bonds in the complex trans-[Pd(Fmes)Cl(PPh3)2]. ΔG associated with this motion is 12.8 kcal mol-1, one of the highest values reported so far for rotation around M−PPh3 bonds. Complexes 2 and 6 are redox inactive by cyclic voltammetry in the range −1.8 to +1.8 V.
Journal of Organometallic Chemistry, 1998
High yield methods for the synthesis of cis-[MR2(COD)] (M=Pd, Pt; R=3,5-C6Cl2F3), cis-[MR2(THF)2]... more High yield methods for the synthesis of cis-[MR2(COD)] (M=Pd, Pt; R=3,5-C6Cl2F3), cis-[MR2(THF)2] (M=Pd; Pt), trans-[PdR2L2] (L=tht; SMe2), trans-[PtR2(SMe2)2], and [M2(μ-Cl)2R2L2] (M=Pd, L=NCPh, tht, SMe2; M=Pt, L=tht) are reported. These complexes are general precursors for the preparation of other complexes containing cis-MR2, trans-MR2 and MClR moieties in almost quantitative yields. Thus, by displacement of COD, THF, tht or SMe2 by other
Inorganic Chemistry, 1997
... Poly(2-pyridyl)phosphines, PPy n Ph 3 - n (n = 2, 3), and Their P-Substituted Derivatives as ... more ... Poly(2-pyridyl)phosphines, PPy n Ph 3 - n (n = 2, 3), and Their P-Substituted Derivatives as Tripodal Ligands in Molybdenum(0) Carbonyl Complexes. ... Juan A. Casares, Pablo Espinet,* Rosa Hernando, Gonzalo Iturbe, and Fernando Villafañe. ...
Chemical Communications, 2001
The main sequential intermediates involved in a real catalytic cycle of the Stille reaction (the ... more The main sequential intermediates involved in a real catalytic cycle of the Stille reaction (the coupling of ROTf with CH 2 NCHSnBu 3 catalyzed by [PdR(OTf)(dppe)]; R = aryl) are observed and characterized unequivocally before the coupling product is released.
Journal of Materials Chemistry - J MATER CHEM, 1997
... Silverio Coco,a Pablo Espinet,*a José M. Martın-Alvareza and Anne-Marie Levelutb aDepartament... more ... Silverio Coco,a Pablo Espinet,*a José M. Martın-Alvareza and Anne-Marie Levelutb aDepartamento de Quımica Inorgánica, Facultad de Ciencias, Universidad de Valladolid, E-47005 Valladolid, Spain bL ... Found: C, 37.65; H, 3.97; N, 3.08%); DSC/°CK–K∞ 146.9 (2.1), K∞–S ...
Chemistry of Materials - CHEM MATER, 2004
... Beatriz Ballesteros, Silverio Coco, and Pablo Espinet*. ... weighing, mixing, and heating of ... more ... Beatriz Ballesteros, Silverio Coco, and Pablo Espinet*. ... weighing, mixing, and heating of the samples) and the effect of the heating rate in viscous materials, makes it advisable to give the transition temperatures in this paper an allowance of ±1 °C. X-ray diffraction experiments on ...
Organometallics, 2002
ABSTRACT The neutral palladium complex [Pd(C6F5)Br(NCMe)2] (1) was found to effect the polymeriza... more ABSTRACT The neutral palladium complex [Pd(C6F5)Br(NCMe)2] (1) was found to effect the polymerization of acrylates upon addition of 1 equiv of a monodentate phosphine or pyridine or an excess of halide. Methyl methacrylate was not polymerized, and furthermore, its addition stopped the progress of independently initiated methyl acrylate polymerization in the phosphine-based system. Addition of ethene also inhibited the polymerization of methyl acrylate. However, over 10 mol % incorporation of 1-hexene in the polymer was achieved when the latter was added together with methyl acrylate. The polymerizaion mechanism is discussed.
Organometallics, 1999
... N. Marta Catalina, Pablo Espinet,* and Rocío Redón. ... Abstract. Abstract Image. The behavio... more ... N. Marta Catalina, Pablo Espinet,* and Rocío Redón. ... Abstract. Abstract Image. The behavior of palladium C-bound enolates [Pd(CH 2 C(O)CR 3 )Cl(PPh 3 ) 2 ] (R = H, 1; R = Me, 2) and [Pd(CH 2 C(O)CR 3 )(PPh 3 ) 2 (NCMe)](BF 4 ) (R = H, 5; R = Me, 6) has been studied. ...
Organometallics, 2008
Neutral trans-[Pd(C 6 F 5 )XL 2 ] (X ) Cl, Br) and cationic trans-[Pd(C 6 F 5 )L 2 (NCMe)]BF 4 (L... more Neutral trans-[Pd(C 6 F 5 )XL 2 ] (X ) Cl, Br) and cationic trans-[Pd(C 6 F 5 )L 2 (NCMe)]BF 4 (L ) SbPh 3 , AsPh 3 , As(C 6 Cl 2 F 3 )Ph 2 , AsCyPh 2 , AsMePh 2 , PPh 3 ) complexes have been studied and tested for norbornene (NB) polymerization and copolymerization with 5-norbornene-2-carboxaldehyde (NB-CHO). The neutral complexes are almost inactive and produce only small amounts of oligomers, but the cationic complexes with arsines and stibines are very good for palladium-catalyzed norbornene polymerization. External coordinating molecules (e.g., ligands or monomers with O-donor groups) compete with the olefin function for the coordination sites on Pd and inhibit the reaction. In spite of this, copolymerization of norbornene and 5-norbornene-2-carboxaldehyde could be achieved, with lower yields and higher incorporations of the functionalized norbornene as the NB:NB-CHO ratio decreases. The complex with the fluorinated arsine AsPh 2 (C 6 Cl 2 F 3 ) is the most active catalyst and allows for easy spectroscopic study of the reacting systems by 19 F NMR. Calorimetry provides straightforward monitoring and detection of activation and deactivation processes in polymerization reactions that give insoluble products and cannot be followed by NMR spectroscopy.