Nine-Vertex Polyhedral Monothiaborane Chemistry. The First nido Thianonaborane: Isolation and Characterization by NMR of the [nido-9-SB8H9]- Anion, and its Conversion to Compounds of the 6-L-arachno-4-SB8H10 Series (where L = SMe2 and Pyridine)

1994 ◽  
Vol 59 (2) ◽  
pp. 367-373 ◽  
Author(s):  
Josef Holub ◽  
John D. Kennedy ◽  
Bohumil Štíbr
Keyword(s):  
Nmr Spectroscopy ◽  
Trifluoroacetic Acid ◽  
Sodium Hydride ◽  
High Yield ◽  
Lewis Bases ◽  
H Nmr ◽  
Sodium Metal ◽  
Isolation And Characterization

Deprotonation of 6(exo)-(SMe2)-arachno-4-SB8H10 either by sodium hydride or sodium metal leads to the isolation in high-yield of the [nido-9-SB8H9]- anion, which has been characterized by 11B and 1H NMR spectroscopy. The nido anion can be reconverted to compounds of the 6(exo)-L-arachno-4-SB8H10 series (where L = SMe2 and pyridine) by reaction with Lewis bases (L) followed by acidification with trifluoroacetic acid.

Nine- and Eight-Vertex Polyhedral Dicarbaborane Chemistry: New arachno and hypho Dicarbaboranes from arachno-4,5-C2B7H13: Isolation and Characterization of the [arachno-4,5-C2B7H12]- and [hypho-7,8-C2B6H13]- Anions, and of the Neutral Ligand Derivatives exo-6-(MeNC)-arachno-4,5-C2B7H11 and exo-5-L-hypho-4,9-C2B7H13 (L = NMe3 and NEt3)

1994 ◽  
Vol 59 (7) ◽  
pp. 1584-1595 ◽  
Author(s):  
Tomáš Jelínek ◽  
Josef Holub ◽  
Bohumil Štíbr ◽  
Xavier L. R. Fontaine ◽  
John D. Kennedy
Keyword(s):  
Nmr Spectroscopy ◽  
Selective Removal ◽  
High Yield ◽  
Two Dimensional ◽  
Neutral Ligand ◽  
Tertiary Amines ◽  
Proton Sponge ◽  
H Nmr ◽  
Isolation And Characterization

Deprotonation of neutral arachno-4,5-C2B7H13 (1) either with 1, 8-(NMe2)2C10H6 (proton sponge, PS) or with a mixture of aqueous K2CO3 and [NMe4]Cl leads to the isolation in high yield of the [arachno-4,5-C2B7H12]- anion (2). Isostructural with this anion is the ligand derivative exo-6-(MeNC)-arachno-4,5-C2B7H11 (3), which is prepared in 20% yield from the reaction between arachno-4,5-C2B7H13 and MeNC in dichloromethane. Under comparable conditions compound 1 with tertiary amines gives the first representatives of the nine-vertex hypho family of dicarbaboranes, the ligand derivatives exo-5-(NR3)-hypho-4,9-C2B7H13 (4a and 4b, where R = Me and Et, respectively) in moderate yields (20 - 55%), whereas the reaction between 1 and aqueous NaCN results in the selective removal of one boron vertex to yield the eight-vertex [hypho-7,8-C2B6H13]- anion (5) in 61% yield. All compounds isolated were characterized by 11B and 1H NMR spectroscopy, with two-dimensional and selective decoupling techniques giving unambiguous assignments.

Nine-Vertex Polyhedral Monoazaborane Chemistry: Synthesis and NMR Characterization of exo-6-Ligand-arachno-4-azanonaboranes(11), 6-L-4-NB8H11

1994 ◽  
Vol 59 (10) ◽  
pp. 2244-2252 ◽  
Author(s):  
Tomáš Jelínek ◽  
Bohumil Štíbr ◽  
John D. Kennedy
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Lewis Bases ◽  
H Nmr ◽  
Nmr Characterization ◽  
Complete Assignment

Reactions between arachno-4-NB8H13 and Lewis bases L in dichloromethane or without solvent generate the previously unreported series of arachno compounds exo-6-L-arachno-4-NB8H11, where L = pyridine (py), quinoline (quin), isoquinoline (i-quin), urotropine (uro), and MeCN. These are characterized by mass spectrometry together with 11B and 1H NMR spectroscopy. The NMR results permit complete assignment of all resonances and thence permit comparison with the structurally similar compounds exo-6-L-arachno-4-EB8H10 (for E = CH2 or S).

Ketone coordination chemistry of the diborane t-BuCH=C[B(C6F5)2]2

1998 ◽  
Vol 76 (9) ◽  
pp. 1249-1255 ◽  
Author(s):  
Katrin Köhler ◽  
Warren E Piers
Keyword(s):  
Coordination Chemistry ◽  
Nmr Spectroscopy ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Key Words ◽  
Lewis Acidity ◽  
High Yield ◽  
Lewis Bases ◽  
Equilibrium Yield ◽  
Boron Center

Reactions of the bifunctional borane t-BuCH=C[B(C6F5)2]2, 1, with simple Lewis bases were investigated to probe its Lewis acidity. Ethereal bases (Et2O, THF) bind very weakly, if at all, as no adducts were detectable in solution. Certain ketones, however, were observed to bind to 1. Acetone forms an adduct, 2, reversibly in solution (Keq at 293 K = 69.1), and the temperature dependence of this equilibrium yield thermodynamic parameters of H° = -59.5 ± 2.0 kJ mol-1; S° = -167 ± 4 J K-1 mol-1. Low temperature NMR spectroscopy suggests that the acetone binds to the more sterically accessible boron center trans to the t-Bu group. Ketone binding is strengthened when 2,3-diphenylcyclopropenone is reacted with 1, irreversibly forming an isolable adduct, 4, in high yield (95%). The availability of a resonance form incorporating the aromatic cyclopropenyl cation contributes to the added stability of this adduct in comparison to 2.Key words: organoboranes, diboranes, ketone complexes.

Regioselectivity in SNH reactions of some 3-nitro-1,5-naphthyridines with chloromethyl phenyl sulfone

2004 ◽  
Vol 82 (5) ◽  
pp. 567-570 ◽  
Author(s):  
Maria Grzegożek ◽  
Barbara Szpakiewicz
Keyword(s):  
Nmr Spectroscopy ◽  
Nucleophilic Substitution ◽  
Key Words ◽  
High Yield ◽  
Vicarious Nucleophilic Substitution ◽  
H Nmr ◽  
Phenyl Sulfone ◽  
Convenient Synthesis ◽  
Key Words 3 ◽  
Hydrogen Substitution

3-Nitro-1,5-naphthyridine and its 2-substituted derivatives react with the carbanion of chloromethyl phenyl sulfone to give hydrogen-substitution products at position 4 in high yield. The intermediacy of 4-(phenylsulfonyl)chloromethyl σ adducts of 2-R-3-nitro-1,5-naphthyridines (R = H, D, Cl, OC2H5, NHCH3, OH) was established by 1H NMR spectroscopy. A convenient synthesis of 2-N-methylamino-3-nitro-1,5-naphthyridine is reported. Key words: 3-nitro-1,5-naphthyridines, anionic (phenylsulfonyl)chloromethyl σ adducts, vicarious nucleophilic substitution.

α-Aminoacyl derivatives of α,ω-diaminopoly(oxyethylene)

1987 ◽  
Vol 52 (8) ◽  
pp. 1922-1927
Author(s):  
Bohumil Masař ◽  
Pavel Schmidt ◽  
Hana Pivcová ◽  
Pavel Čefelín
Keyword(s):  
Amino Acids ◽  
Nmr Spectroscopy ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Trifluoroacetic Acid ◽  
Complete Removal ◽  
Protective Group ◽  
H Nmr ◽  
Layer Chromatography ◽  
Derivatives Of

By reacting p-nitrophenyl esters of L-α-amino acids with α-(3-aminopropyl)-ω-(aminomethyl)-poly(oxyethylene), diamides having the structure [X-NHCH(R)CONH]2Mx' were prepared, X being the protective group Boc or Z, R being residues of glutamic and aspartic acid, phenylalanine and tyrosine, and Mx' being the poly(oxyethylene) chain with the (-CH2)3- and -CH2- endgroups. The diamides were characterized by IR and 1H NMR spectroscopy and thin-layer chromatography. After complete removal of tert-butyloxycarbonyl groups from diamides (X = Boc), deprotected α-aminoacyl derivatives were characterized as trifluoroacetic acid salts.

A twist on Hellwinkel’s salt, [P(2,2′-biphenyl)2]+[P(2,2′-biphenyl)3]–

2018 ◽  
Vol 96 (6) ◽  
pp. 526-533 ◽  
Author(s):  
Khatera Hazin ◽  
Derek P. Gates
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Spiro Compound ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Isolation And Characterization

Treating PCl5 with C12H8Li2, generated from either C12H10, C12H8Br2, or C12H8I2, affords three products in different ratios depending on the source of the lithiated biphenyl. Hellwinkel’s salt [P(C12H8)2][P(C12H8)3] ([1][2]) and another product [P(C12H8)(C24H16)][P(C12H8)3] ([1′][2]) were obtained by reacting PCl5 with 2,2′-dilithiobiphenyl [Route A: 2.5 equiv.; obtained from biphenyl, n-BuLi, and TMEDA; Route B: 3.0 equiv.; obtained from 2,2′-diiodobiphenyl and n-BuLi; Route C: 4.0 equiv.; obtained from 2,2′-dibromobiphenyl and n-BuLi]. The synthesis, isolation, and characterization of the chiral spiro-compound [1′][2] and the characterization of the pentavalent phosphorane [P(C12H8)2(C12H9)] (3) are reported. The complex [1′][2] was characterized by 31P{1H} NMR spectroscopy, X-ray crystallography, and mass spectrometry. The pentavalent compound (3) was characterized by 31P{1H} NMR spectroscopy and X-ray crystallography.

Hydrolysis of ethylenediphosphinetetraacetate anions

1983 ◽  
Vol 48 (6) ◽  
pp. 1552-1557
Author(s):  
Jana Podlahová ◽  
Jaroslav Podlaha
Keyword(s):  
Nmr Spectroscopy ◽  
Aqueous Solutions ◽  
Stability Of Solutions ◽  
Laboratory Temperature ◽  
H Nmr ◽  
Isolation And Characterization ◽  
Acid And Base ◽  
The Stability ◽  
Hydrolysis Of

The anions of ethylenediphosphinetetraacetic acid are hydrolyzed in aqueous solutions at 80 °C in the two following reactions: ((OOCCH2)2PCH2CH2P(CH2COO)2)4- → (OOCCH2(O)HPCH2CH2PH(O)CH2COO)2- → (O(O)HPCH2CH2PH(O)O)2-. Both reactions are acid and base catalyzed so that, at pH < 12, the first reaction is much faster than the second. The reaction course was studied by 1H NMR spectroscopy and by isolation and characterization of the products. The effect of both reactions on the stability of solutions of ethylenediphosphinetetraacetic acid and their salts is negligible at laboratory temperature.

Conformational study on ribonucleoside O-phosphonylmethyl derivatives by 1H NMR spectroscopy

1985 ◽  
Vol 50 (8) ◽  
pp. 1899-1905 ◽  
Author(s):  
Milena Masojídková ◽  
Jaroslav Zajíček ◽  
Miloš Buděšínský ◽  
Ivan Rosenberg ◽  
Antonín Holý
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Conformational Study ◽  
H Nmr ◽  
Conformational Properties

Conformational properties of ribonucleoside 5'-O-phosphonylmethyl derivatives have been determined by 1H NMR spectroscopy and compared with those of natural nucleosides and 5'-nucleotides.

NMR spectroscopic investigation of p-substituted 2,4,4,6-tetraphenyl-1,4-dihydropyridines and their oxa and thia analogues

1989 ◽  
Vol 54 (7) ◽  
pp. 1854-1869 ◽  
Author(s):  
Marián Schwarz ◽  
Petr Trška ◽  
Josef Kuthan
Keyword(s):  
Nmr Spectroscopy ◽  
Trifluoroacetic Acid ◽  
Spectroscopic Investigation ◽  
Nmr Spectra ◽  
Dynamic Equilibrium

The 1H, 13C and 19F NMR spectra of photochromic p-substituted 2,4,4,6-tetraphenyl-1,4-dihydropyridines IIa-IIg, 1-methyl-2,4,4,6-tetraphenyl-1,4-dihydropyridines IIIa-IIIg, 2,4,4,6-tetraphenyl-4H-pyrans IVa-IVh, and 2,4,4,6-tetraphenyl-4H-thiopyran V were inspected; it was found that compounds IIa-IIg occur in a dynamic equilibrium with their dihydro tautomer VIa-VIg. Also deuteriodeprotonation of IIa and IIIa and their reaction with trifluoroacetic acid were investigated by NMR spectroscopy.

Ten-Vertex Polyhedral Monocarbaborane Chemistry. The Novel High-Yield Formation of the Ten-Vertex closo Compound [6-(PMe2Ph)-closo-1-CB9H9] from the Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11]

1993 ◽  
Vol 58 (12) ◽  
pp. 2924-2935 ◽  
Author(s):  
Jane H. Jones ◽  
Bohumil Štíbr ◽  
John D. Kennedy ◽  
Mark Thornton-Pett
Keyword(s):  
Nmr Spectroscopy ◽  
Diffraction Analysis ◽  
High Yield ◽  
Monoclinic Space Group ◽  
The Novel ◽  
X Ray Diffraction ◽  
Metal Centre ◽  
X Ray ◽  
Yield Formation ◽  
Boiling Toluene

Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11] in boiling toluene solution results in an elimination of the platinum centre and cluster closure to give the ten-vertex closo species [6-(PMe2Ph)-closo-1-CB9H9] in 85% yield as a colourles air stable solid. The product is characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Crystals (from hexane-dichloromethane) are monoclinic, space group P21/c, with a = 903.20(9), b = 1 481.86(11), c = 2 320.0(2) pm, β = 97.860(7)° and Z = 8, and the structure has been refined to R(Rw) = 0.045(0.051) for 3 281 observed reflections with Fo > 2.0σ(Fo). The clean high-yield elimination of a metal centre from a polyhedral metallaborane or metallaheteroborane species is very rare.

Sign in / Sign up

Export Citation Format

Share Document