Gary Balaich - Academia.edu (original) (raw)
Papers by Gary Balaich
Molbank
Reaction of triplet O2 with the bridged dipotassium dicyclopentadienyl salt, ansa-[(CHBut)2(Ph2C5... more Reaction of triplet O2 with the bridged dipotassium dicyclopentadienyl salt, ansa-[(CHBut)2(Ph2C5H2)2]K2(THF)3 1, in dry MeCN facilitated an intramolecular cyclopentadienyl ring-C to ring-C bond formation and the precipitation of the crude product 4,5-di-tert-butyl-1,3,6,8-tetraphenyl-4,5,8a,8b-tetrahydro-as-indacene 2 as an off-white solid in a 73% yield (>95% pure, 1H NMR). Characterization of 2 was carried out using multinuclear NMR spectroscopy (1H and 13C), single-crystal X-ray crystallography, FTIR spectroscopy, and thermal analytical techniques (SDT, DSC). The molecular structure consisted of a rigid, C2-symmetric six-membered ring in a chair conformation with four of the ring-C atoms fused to 1,3-diphenylcyclopentadiene rings and the other two ring-C atoms substituted with trans di-axial But groups.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Acta Crystallographica Section E: Crystallographic Communications, 2021
The title compound crystallizes with half of a molecule per asymmetric unit and exhibits bond len... more The title compound crystallizes with half of a molecule per asymmetric unit and exhibits bond lengths and angles typical of α-diketones. A network of C—H⋯F contacts and π–π stacking interactions is observed within the structure.
![Research paper thumbnail of (E)-1-[1-(3-Phenylcyclopenta-2,4-dien-1-ylidene)ethyl]pyrrolidine](https://attachments.academia-assets.com/86036736/thumbnails/1.jpg)
](IUCrData, Jun 5, 2018
The title compound, C 17 H 19 N, is a disubstituted pentafulvene obtained from the hydroamination... more The title compound, C 17 H 19 N, is a disubstituted pentafulvene obtained from the hydroamination of 1-phenyl-3-trimethylsilylethynylcyclopentadiene and has monoclinic P2 1 /n symmetry at 100 K. C-HÁ Á Á ring interactions between neighboring molecules consolidate the packing. To the authors' knowledge, this reaction is the first reported example of a non-transition metal catalyzed hydroamination with concomitant desilylation. Structure description The title compound (Fig. 1) crystallizes in the monoclinic space group P2 1 /n with one molecule in the asymmetric unit. Within the fulvene system, the expected alternating short and long bond distances as well as intra-ring bond angles were observed. The 2-phenyl substituent is rotated 24.24 (6) from the fulvene plane. The geometry around N1 is trigonal planar and the N1/C14/C17 plane is rotated by only 15.42 (9) from the fulvene plane, presumably to allow partial conjugation of the nitrogen lone pair into the fulvene system. Only two broad peaks are observed for the pyrrolidine methylene protons in the 1 H NMR spectrum, indicating N-C bond rotation and nitrogen inversion on the NMR timescale. C-HÁ Á Á ring interactions (Table 1, Fig. 2) between neighboring molecules consolidate the packing. Synthesis and crystallization Synthesis of 1-phenyl-3-trimethylsilylethynylcyclopentadiene. To a vigorously stirred solution of ethynyltrimethylsilane (7.0 ml, 50.6 mmol) in anhydrous Et 2 O (25 ml) at À94 C under N 2 , n-BuLi (2.5 M, 19.2 ml, 48.0 mmol) was added dropwise over 20 min. and allowed to stir for 1 h. A solution of 3-phenylcyclopent-2-en-1-one (3.99 g, 25.2 mmol) in anhydrous Et 2 O (250 ml) was added dropwise over 20 min. The resulting
Acta Crystallographica Section E Crystallographic Communications, 2019
Five new crystal structures of perfluoropyridine substituted in the 4-position with phenoxy, 4-br... more Five new crystal structures of perfluoropyridine substituted in the 4-position with phenoxy, 4-bromophenoxy, naphthalen-2-yloxy, 6-bromonaphthalen-2-yloxy, and 4,4′-biphenoxy are reported, viz. 2,3,5,6-tetrafluoro-4-phenoxypyridine, C11H5F4NO (I), 4-(4-bromophenoxy)-2,3,5,6-tetrafluoropyridine, C11H4BrF4NO (II), 2,3,5,6-tetrafluoro-4-[(naphthalen-2-yl)oxy]pyridine, C15H7F4NO (III), 4-[(6-bromonaphthalen-2-yl)oxy]-2,3,5,6-tetrafluoropyridine, C15H6BrF4NO (IV), and 2,2′-bis[(perfluoropyridin-4-yl)oxy]-1,1′-biphenyl, C22H8F8N2O2 (V). The dihedral angles between the aromatic ring systems in I–IV are 78.74 (8), 56.35 (8), 74.30 (7), and 64.34 (19)°, respectively. The complete molecule of V is generated by a crystallographic twofold axis: the dihedral angle between the pyridine ring and adjacent phenyl ring is 80.89 (5)° and the equivalent angle between the biphenyl rings is 27.30 (5)°. In each crystal, the packing is driven by C—H...F interactions, along with a variety of C—F...π, C—H......
Inorganic Chemistry, 1997
Transition metal complexes have important utility as monomer units in polymer chains, because the... more Transition metal complexes have important utility as monomer units in polymer chains, because they ultimately determine the unique electronic, optical, and catalytic properties of the polymer. 1,2 Our interest in synthesizing organometallic polymers containing the cobalt ...
This report was prepared as an account of work sponsored by an agency of the United States Govern... more This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Organometallics, 1993
The sodium amalgam (two Na per Ti) reduction of hydrocarbon solutions of [Ti(OAr")zCl~l (OAr" = 2... more The sodium amalgam (two Na per Ti) reduction of hydrocarbon solutions of [Ti(OAr")zCl~l (OAr" = 2,6-diphenylphenoxide) in the presence of EtC=CEt, ButC=CH, and MeCECPh (1 2 equiv) produces the corresponding titanacyclopentadiene complexes [(Ar"0)2Ti(C4Et4)1 (l), [(Ar"O)z(C4H2But2)] (2), and [(Ar"O)zTi(C4MezPhz)] (3). The use of less bulky substituents on the alkyne substrate in such reactions leads to mixtures of aromatic compounds due to cyclotrimerization reactions. The solid state structure of 1 shows a pseudotetrahedral environment about the titanium metal center with a planar titanacyclopentadiene ring. The lH and 13C NMR spectra of solutions of 1-3 show no exchange of a-and 0-positions of the metallacycle rings. Only the 2,4-regioisomer of 2 and 3 was detected in solution. Reaction of 1 with P h C E C P h produced [(Ar"0)2Ti(C4Ph)1 (4). Reaction of 1-4 with protic reagents yielded the corresponding diene derivatives while iodination of 1 and 2 yielded 1,4-diiodo-1,3-butadienes. Compounds 1-4 will catalyze the cyclotrimerization of a range of alkynes. Terminal alkynes with small substituents produce the 1,2,4-trisubstituted benzene preferentially in an exothermic reaction. The more bulky substrates ButC=CH and Me3SiC=CH react more slowly and only the symmetrical 1,3,5-isomer is produced. The reaction of the titanacyclopentadiene rings in 1 and 2 with a variety of unsaturated organic molecules has been investigated. Reaction of 1 with ButNC leads to a new organometallic compound 5 containing an T2-C,N-bound cyclopentadiene-imine which was structurally characterized as a pyridine adduct (7). The solid state structure of 7 showed a structure related to other titanium +C,N-bound imine complexes, but with a long TiC distance of 2.262(3) A. Reaction of 1 or 2 with benzonitrile leads to the elimination of 1 equiv of the corresponding pyridine. The organometallic product of these reactions was identified as a dimeric material [ (Ar"O)zTi(p-PhCN)2Ti(OAr")z] (8) containing two bridging benzonitrile ligands. The solid state structure of 8 showed the bridging PhCN unit to be highly reduced and strongly bound to the titanium metal centers. The lack of reactivity of 8 precluded the catalytic formation of pyridines. Both compounds 1 and 2 undergo ring expansion with Ph2C0 a t 25 "C to form the corresponding 2-oxatitanacyclohepta-4,6-diene derivatives 9 and 10. In 10 the ketone was found to insert into the side of the titanacyclopentadiene ring containing the less bulky substituent, leading to a single regioisomer. Reaction of 1 with PhzCO a t 100 "C led to the 2-oxatitanacyclopent-4-ene complex [(Ar"0)~Ti(0CPhzCEtCEt)l (1 1) along with 1 equiv of 3-hexyne. Attempts to interconvert 9 and 11 failed. Further elaboration of the seven membered ring in 9 by reaction with ButNC yielded the 02-iminoacyl derivative 12. The conformation of the large metallacycle rings in 9 and 12 was analyzed by carrying out single crystal X-ray diffraction anal ses. Crystal data: a t 20 "C for Ti02C48H4 (1) a = 12.627(3) = 1.205 g ~m-~ in space group Pi; for TiozNzC~8H60 (7) a t-105 "c a = 12.554(4) A, b = 17.934(5) A, c = 21.567(6) A, = 102.38(2)", Z = 4, dc&d = 1.211 g cm-3 in space group P21/n; for Ti2O4N2C98H,4 (8) a t-50 "C a = 23.100(4) A, b = 12.656(3) A, c = 27.486(7) A, = 109.09(2)", Z = 4, dc&d = 1.259 g cm-3 in space group C2/c; for TiO3C68H64 (9) a t-50 " C a = 12.147(3) A,
![Research paper thumbnail of Regio- and Stereoselective Synthesis of the 1,3-Cyclohexadiene Nucleus by [2 + 2 + 2] Cycloaddition Reactions Catalyzed by Titanium Aryloxide Compounds](https://attachments.academia-assets.com/86036651/thumbnails/1.jpg)
](Journal of the American Chemical Society, 1997
A variety of titanium aryloxide reagents catalyze the cross coupling of two alkyne units with 1 e... more A variety of titanium aryloxide reagents catalyze the cross coupling of two alkyne units with 1 equiv of olefin to produce the 1,3-cyclohexadiene nucleus. Catalysts include isolated titanacyclopentadiene or titanacyclopentane complexes. The reaction proceeds via attack of the olefin upon a titanacyclopentadiene compound initially formed by coupling of two alkyne units. The reaction is limited to bulky alkyne substrates that undergo slow catalytic cyclotrimerization via competing attack of a third alkyne upon the titanacyclopentadiene ring. The organic products isolated are typically the result of an isomerization within the initially produced 1,3-cyclohexadiene nucleus. Mechanistic studies show that these isomerization processes occur via sequential, metal-mediated 1,5-hydrogen shifts upon a single face of the six-membered ring, exclusively leading to a cis-stereochemistry within the final products. In the reactions of the diynes RsCtC(CH 2) 4 CtCsR (R) Et, SiMe 3), coupling with ethylene and R-olefins produces a variety of substituted hexalins. A combination of NMR spectroscopy, photochemistry, and molecular mechanics calculations has been applied to determine the stereochemistry and ground state conformations adopted by the product 1,3-cyclohexadienes and hexalins. The primary and secondary photoproducts obtained from some of these 1,3cyclohexadiene compounds have been characterized.
Desalination, 2012
The present work demonstrates the electrochemical characterizations of polystyrene based calcium-... more The present work demonstrates the electrochemical characterizations of polystyrene based calcium-strontium phosphate composite membranes prepared by sol-gel process. Polystyrene based magnesium-strontium (CSP) composite membrane was characterized by XRD, FTIR, SEM, and antibacterial studies. The membrane was found to be crystalline in nature with uniform arrangement of particles indicating no sign of visible cracks and showed good inhibitory effects against gram positive as well as gram negative bacteria. The IR spectra confirm the binding of the composites with the polystyrene. The observed membrane potential of polystyrene based calcium-strontium phosphate composite membrane were measured with uni-univalent electrolytes solutions using saturated calomel electrodes and followed the order LiClN NaClN KCl. Thus, the membrane was found to be cation-selective. Membrane potential data have been used to calculate transport number, mobility ratio, distribution coefficient, charge effectiveness, and also to derive the fixed charge density which is a key parameter to govern the membrane phenomena by utilizing Teorell, Meyer, and Sievers method. The order of surface charge density for uni-univalent electrolytes solution was found to be KCl N NaClN LiCl.
Acta Crystallographica Section E Structure Reports Online, 2002
The sodium naphthalenide reduction of 1,3,6-tri-tert-butylfulvene gave the dimer, rac-3,4-bis(1,... more The sodium naphthalenide reduction of 1,3,6-tri-tert-butylfulvene gave the dimer, rac-3,4-bis(1,4-di-tertbutylcyclopenta-1,3-dien-2-yl)-2,2,5,5-tetramethylhexane [C36H62, (II)] after protonation of the disodium salt of the bis(cyclopentadienylethane) intermediate. Bond distances and angles for (II) are consistent with a bis(cyclopentadiene) structure. The ansa bridge bond is long, at 1.592 (2) A. The substitution pattern on the cyclopentadiene rings, as well as the ansa bridge, result in an overall C2 symmetry for (II).
Molbank
Reaction of triplet O2 with the bridged dipotassium dicyclopentadienyl salt, ansa-[(CHBut)2(Ph2C5... more Reaction of triplet O2 with the bridged dipotassium dicyclopentadienyl salt, ansa-[(CHBut)2(Ph2C5H2)2]K2(THF)3 1, in dry MeCN facilitated an intramolecular cyclopentadienyl ring-C to ring-C bond formation and the precipitation of the crude product 4,5-di-tert-butyl-1,3,6,8-tetraphenyl-4,5,8a,8b-tetrahydro-as-indacene 2 as an off-white solid in a 73% yield (>95% pure, 1H NMR). Characterization of 2 was carried out using multinuclear NMR spectroscopy (1H and 13C), single-crystal X-ray crystallography, FTIR spectroscopy, and thermal analytical techniques (SDT, DSC). The molecular structure consisted of a rigid, C2-symmetric six-membered ring in a chair conformation with four of the ring-C atoms fused to 1,3-diphenylcyclopentadiene rings and the other two ring-C atoms substituted with trans di-axial But groups.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Acta Crystallographica Section E: Crystallographic Communications, 2021
The title compound crystallizes with half of a molecule per asymmetric unit and exhibits bond len... more The title compound crystallizes with half of a molecule per asymmetric unit and exhibits bond lengths and angles typical of α-diketones. A network of C—H⋯F contacts and π–π stacking interactions is observed within the structure.
IUCrData, Jun 5, 2018
The title compound, C 17 H 19 N, is a disubstituted pentafulvene obtained from the hydroamination... more The title compound, C 17 H 19 N, is a disubstituted pentafulvene obtained from the hydroamination of 1-phenyl-3-trimethylsilylethynylcyclopentadiene and has monoclinic P2 1 /n symmetry at 100 K. C-HÁ Á Á ring interactions between neighboring molecules consolidate the packing. To the authors' knowledge, this reaction is the first reported example of a non-transition metal catalyzed hydroamination with concomitant desilylation. Structure description The title compound (Fig. 1) crystallizes in the monoclinic space group P2 1 /n with one molecule in the asymmetric unit. Within the fulvene system, the expected alternating short and long bond distances as well as intra-ring bond angles were observed. The 2-phenyl substituent is rotated 24.24 (6) from the fulvene plane. The geometry around N1 is trigonal planar and the N1/C14/C17 plane is rotated by only 15.42 (9) from the fulvene plane, presumably to allow partial conjugation of the nitrogen lone pair into the fulvene system. Only two broad peaks are observed for the pyrrolidine methylene protons in the 1 H NMR spectrum, indicating N-C bond rotation and nitrogen inversion on the NMR timescale. C-HÁ Á Á ring interactions (Table 1, Fig. 2) between neighboring molecules consolidate the packing. Synthesis and crystallization Synthesis of 1-phenyl-3-trimethylsilylethynylcyclopentadiene. To a vigorously stirred solution of ethynyltrimethylsilane (7.0 ml, 50.6 mmol) in anhydrous Et 2 O (25 ml) at À94 C under N 2 , n-BuLi (2.5 M, 19.2 ml, 48.0 mmol) was added dropwise over 20 min. and allowed to stir for 1 h. A solution of 3-phenylcyclopent-2-en-1-one (3.99 g, 25.2 mmol) in anhydrous Et 2 O (250 ml) was added dropwise over 20 min. The resulting
Acta Crystallographica Section E Crystallographic Communications, 2019
Five new crystal structures of perfluoropyridine substituted in the 4-position with phenoxy, 4-br... more Five new crystal structures of perfluoropyridine substituted in the 4-position with phenoxy, 4-bromophenoxy, naphthalen-2-yloxy, 6-bromonaphthalen-2-yloxy, and 4,4′-biphenoxy are reported, viz. 2,3,5,6-tetrafluoro-4-phenoxypyridine, C11H5F4NO (I), 4-(4-bromophenoxy)-2,3,5,6-tetrafluoropyridine, C11H4BrF4NO (II), 2,3,5,6-tetrafluoro-4-[(naphthalen-2-yl)oxy]pyridine, C15H7F4NO (III), 4-[(6-bromonaphthalen-2-yl)oxy]-2,3,5,6-tetrafluoropyridine, C15H6BrF4NO (IV), and 2,2′-bis[(perfluoropyridin-4-yl)oxy]-1,1′-biphenyl, C22H8F8N2O2 (V). The dihedral angles between the aromatic ring systems in I–IV are 78.74 (8), 56.35 (8), 74.30 (7), and 64.34 (19)°, respectively. The complete molecule of V is generated by a crystallographic twofold axis: the dihedral angle between the pyridine ring and adjacent phenyl ring is 80.89 (5)° and the equivalent angle between the biphenyl rings is 27.30 (5)°. In each crystal, the packing is driven by C—H...F interactions, along with a variety of C—F...π, C—H......
Inorganic Chemistry, 1997
Transition metal complexes have important utility as monomer units in polymer chains, because the... more Transition metal complexes have important utility as monomer units in polymer chains, because they ultimately determine the unique electronic, optical, and catalytic properties of the polymer. 1,2 Our interest in synthesizing organometallic polymers containing the cobalt ...
This report was prepared as an account of work sponsored by an agency of the United States Govern... more This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Organometallics, 1993
The sodium amalgam (two Na per Ti) reduction of hydrocarbon solutions of [Ti(OAr")zCl~l (OAr" = 2... more The sodium amalgam (two Na per Ti) reduction of hydrocarbon solutions of [Ti(OAr")zCl~l (OAr" = 2,6-diphenylphenoxide) in the presence of EtC=CEt, ButC=CH, and MeCECPh (1 2 equiv) produces the corresponding titanacyclopentadiene complexes [(Ar"0)2Ti(C4Et4)1 (l), [(Ar"O)z(C4H2But2)] (2), and [(Ar"O)zTi(C4MezPhz)] (3). The use of less bulky substituents on the alkyne substrate in such reactions leads to mixtures of aromatic compounds due to cyclotrimerization reactions. The solid state structure of 1 shows a pseudotetrahedral environment about the titanium metal center with a planar titanacyclopentadiene ring. The lH and 13C NMR spectra of solutions of 1-3 show no exchange of a-and 0-positions of the metallacycle rings. Only the 2,4-regioisomer of 2 and 3 was detected in solution. Reaction of 1 with P h C E C P h produced [(Ar"0)2Ti(C4Ph)1 (4). Reaction of 1-4 with protic reagents yielded the corresponding diene derivatives while iodination of 1 and 2 yielded 1,4-diiodo-1,3-butadienes. Compounds 1-4 will catalyze the cyclotrimerization of a range of alkynes. Terminal alkynes with small substituents produce the 1,2,4-trisubstituted benzene preferentially in an exothermic reaction. The more bulky substrates ButC=CH and Me3SiC=CH react more slowly and only the symmetrical 1,3,5-isomer is produced. The reaction of the titanacyclopentadiene rings in 1 and 2 with a variety of unsaturated organic molecules has been investigated. Reaction of 1 with ButNC leads to a new organometallic compound 5 containing an T2-C,N-bound cyclopentadiene-imine which was structurally characterized as a pyridine adduct (7). The solid state structure of 7 showed a structure related to other titanium +C,N-bound imine complexes, but with a long TiC distance of 2.262(3) A. Reaction of 1 or 2 with benzonitrile leads to the elimination of 1 equiv of the corresponding pyridine. The organometallic product of these reactions was identified as a dimeric material [ (Ar"O)zTi(p-PhCN)2Ti(OAr")z] (8) containing two bridging benzonitrile ligands. The solid state structure of 8 showed the bridging PhCN unit to be highly reduced and strongly bound to the titanium metal centers. The lack of reactivity of 8 precluded the catalytic formation of pyridines. Both compounds 1 and 2 undergo ring expansion with Ph2C0 a t 25 "C to form the corresponding 2-oxatitanacyclohepta-4,6-diene derivatives 9 and 10. In 10 the ketone was found to insert into the side of the titanacyclopentadiene ring containing the less bulky substituent, leading to a single regioisomer. Reaction of 1 with PhzCO a t 100 "C led to the 2-oxatitanacyclopent-4-ene complex [(Ar"0)~Ti(0CPhzCEtCEt)l (1 1) along with 1 equiv of 3-hexyne. Attempts to interconvert 9 and 11 failed. Further elaboration of the seven membered ring in 9 by reaction with ButNC yielded the 02-iminoacyl derivative 12. The conformation of the large metallacycle rings in 9 and 12 was analyzed by carrying out single crystal X-ray diffraction anal ses. Crystal data: a t 20 "C for Ti02C48H4 (1) a = 12.627(3) = 1.205 g ~m-~ in space group Pi; for TiozNzC~8H60 (7) a t-105 "c a = 12.554(4) A, b = 17.934(5) A, c = 21.567(6) A, = 102.38(2)", Z = 4, dc&d = 1.211 g cm-3 in space group P21/n; for Ti2O4N2C98H,4 (8) a t-50 "C a = 23.100(4) A, b = 12.656(3) A, c = 27.486(7) A, = 109.09(2)", Z = 4, dc&d = 1.259 g cm-3 in space group C2/c; for TiO3C68H64 (9) a t-50 " C a = 12.147(3) A,
Journal of the American Chemical Society, 1997
A variety of titanium aryloxide reagents catalyze the cross coupling of two alkyne units with 1 e... more A variety of titanium aryloxide reagents catalyze the cross coupling of two alkyne units with 1 equiv of olefin to produce the 1,3-cyclohexadiene nucleus. Catalysts include isolated titanacyclopentadiene or titanacyclopentane complexes. The reaction proceeds via attack of the olefin upon a titanacyclopentadiene compound initially formed by coupling of two alkyne units. The reaction is limited to bulky alkyne substrates that undergo slow catalytic cyclotrimerization via competing attack of a third alkyne upon the titanacyclopentadiene ring. The organic products isolated are typically the result of an isomerization within the initially produced 1,3-cyclohexadiene nucleus. Mechanistic studies show that these isomerization processes occur via sequential, metal-mediated 1,5-hydrogen shifts upon a single face of the six-membered ring, exclusively leading to a cis-stereochemistry within the final products. In the reactions of the diynes RsCtC(CH 2) 4 CtCsR (R) Et, SiMe 3), coupling with ethylene and R-olefins produces a variety of substituted hexalins. A combination of NMR spectroscopy, photochemistry, and molecular mechanics calculations has been applied to determine the stereochemistry and ground state conformations adopted by the product 1,3-cyclohexadienes and hexalins. The primary and secondary photoproducts obtained from some of these 1,3cyclohexadiene compounds have been characterized.
Desalination, 2012
The present work demonstrates the electrochemical characterizations of polystyrene based calcium-... more The present work demonstrates the electrochemical characterizations of polystyrene based calcium-strontium phosphate composite membranes prepared by sol-gel process. Polystyrene based magnesium-strontium (CSP) composite membrane was characterized by XRD, FTIR, SEM, and antibacterial studies. The membrane was found to be crystalline in nature with uniform arrangement of particles indicating no sign of visible cracks and showed good inhibitory effects against gram positive as well as gram negative bacteria. The IR spectra confirm the binding of the composites with the polystyrene. The observed membrane potential of polystyrene based calcium-strontium phosphate composite membrane were measured with uni-univalent electrolytes solutions using saturated calomel electrodes and followed the order LiClN NaClN KCl. Thus, the membrane was found to be cation-selective. Membrane potential data have been used to calculate transport number, mobility ratio, distribution coefficient, charge effectiveness, and also to derive the fixed charge density which is a key parameter to govern the membrane phenomena by utilizing Teorell, Meyer, and Sievers method. The order of surface charge density for uni-univalent electrolytes solution was found to be KCl N NaClN LiCl.
Acta Crystallographica Section E Structure Reports Online, 2002
The sodium naphthalenide reduction of 1,3,6-tri-tert-butylfulvene gave the dimer, rac-3,4-bis(1,... more The sodium naphthalenide reduction of 1,3,6-tri-tert-butylfulvene gave the dimer, rac-3,4-bis(1,4-di-tertbutylcyclopenta-1,3-dien-2-yl)-2,2,5,5-tetramethylhexane [C36H62, (II)] after protonation of the disodium salt of the bis(cyclopentadienylethane) intermediate. Bond distances and angles for (II) are consistent with a bis(cyclopentadiene) structure. The ansa bridge bond is long, at 1.592 (2) A. The substitution pattern on the cyclopentadiene rings, as well as the ansa bridge, result in an overall C2 symmetry for (II).