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 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.

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.

Selective dismantling of closo-1,2-C2B10H12 to lower-cage dicarbaborane systems

1991 ◽  
Vol 56 (8) ◽  
pp. 1618-1635 ◽  
Author(s):  
Jaromír Plešek ◽  
Bohumil Štíbr ◽  
Xavier L. R. Fontaine ◽  
John D. Kennedy ◽  
Stanislav Heřmánek ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Solution Structure ◽  
High Yield ◽  
Two Dimensional ◽  
Oxidizing Agents ◽  
Elimination Reactions

A modified, high-yield synthesis of the two isomeric nido twelve-vertex [C2B10H13]- anions, "reactive" [nido-7,9-C2B10H13]- and "unreactive" [nido-7,12-C2B10H13]-, has been developed. A solution structure for the reactive [nido-7,9-C2H10B13]- isomer is proposed on the basis of the result of two-dimensional 11B and 1H correlation NMR spectroscopy. It is concluded that there is a marked similarity between this species and the eleven-vertex congener [nido-7,8-C2B9H12]-. In accord with this parallel, the "reactive" twelve-vertex species is found to undergo selective boron-vertex elimination reactions in the presence of oxidizing agents. These reactions give excellent yields of smaller-cage nido dicarbaborane compounds, namely [nido-7,8-C2B9H12]-, [9-(SMe2)-nido-7,8-C2B9H11], and nido-5,6-C2B8H12. NMR spectroscopy assigns cluster 11B and 1H resonances for all the compounds isolated, and thence permits comparison with the equivalent shielding patterns of structurally related analogues such as [nido-7-CB10H13]- and [nido-7,9-C2B9H12]-.

scholarly journals Efficient resolution of racemic crown-shaped cyclotriveratrylene derivatives and isolation and characterization of the intermediate saddle isomer

2019 ◽  
Vol 15 ◽  
pp. 1339-1346
Author(s):  
Sven Götz ◽  
Andreas Schneider ◽  
Arne Lützen
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Nmr Spectroscopy ◽  
High Performance ◽  
Chiral Stationary Phase ◽  
Hplc Separation ◽  
Promising Alternative ◽  
Isolation And Characterization ◽  
C Nmr

The preparative resolution of a trifunctionalized C 3-symmetrical chiral cyclotriveratrylene derivative was achieved via high-performance liquid chromatography (HPLC) on a chiral stationary phase. This approach is a promising alternative to the previously reported resolution through formation of diastereomeric esters because it involves fewer synthetic steps and is less prone to thermal (re)racemization. During these studies an intermediate saddle conformer could also be isolated and characterized by 1H and 13C NMR spectroscopy. The HPLC separation method was further developed in order to allow investigations on the racemization behavior of the cyclotriveratrylene derivative.

Isolation and characterization of new heme analogues with weakly coordinating anions: Formation of monoimidazole complex, OEPFe(Im)(SbF6)

2007 ◽  
Vol 11 (09) ◽  
pp. 691-696 ◽  
Author(s):  
Mozhgan Khorasani-Motlagh ◽  
Meissam Noroozifar ◽  
Asieh Moodi
Keyword(s):  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Spectroscopic Methods ◽  
H Nmr ◽  
Weakly Coordinating Anions ◽  
Axial Ligands ◽  
Isolation And Characterization ◽  
Pulse Polarography ◽  
Weakly Coordinating

The effects of weakly coordinating anions, BF 4, AsF 6 and SbF 6, as axial ligands on the formation and coordination chemistry of heme analogues have been examined. Three new five-coordinate and stable iron(III) heme analogues, OEPFeX , where OEP is the dianion of octaethylporphyrin and X = BF 4, AsF 6 and SbF 6, have been isolated. The compounds have been characterized by different spectroscopic methods as well as elemental analysis. 1 H NMR spectroscopy and magnetic moment measurements show that the OEPFeX are paramagnetic and iron is five-coordinate. In addition, monoimidazole ferric-porphyrin complex, OEPFe ( Im )( SbF 6) has been prepared in solution, by starting with OEPFe ( SbF 6). The electrochemical properties of OEPFeX ( X = BF 4, AsF 6, SbF 6) have been studied by cyclic voltammetry and differential pulse polarography.

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