Ravindra K. Kanjolia

Synthesis and characterization of some aminophosphonium chlorides

Abstract R 3 P reacts with NR′R″Cl to give good yields of a new homologous series of aminophosphonium chlorides, [R 3 PNR′R″]Cl, in which R = Me, Et, n-Pr and Ph; R′ and/or R″ = H, Me. IR, NMR and mass spectral data suggest that the phosphorous is tetracoordinate. When MeN(H)Cl is synthesized by the gas phase reaction of MeNH 2 and Cl 2 , an optically active solution of MeN(H)Cl is obtained and the resulting aminophosphonium chlorides exhibit chirality. Electrical conductivity and temperature and concentration dependent NMR studies indicate ion pairing between the [R 3 PNR′R″] + and Cl − ions in solution. Quaternization of the phosphorous produces a large 31 P downfield chemical shift, a downfield 1 H chemical shift for the protons in the alkyl chains and an upfield 13 C chemical shift for the carbons in the alkyl chains. α- and β-deshielding and γ-shielding effects are observed in the 13 C NMR spectra with substitution on the phosphorous and nitrogen atoms. The mass spectral data, fragment ion identities and fragmentation modes are given for the compounds. Ions corresponding to a variety of P 2 N and PN containing species in addition to those associated with fragmentation of the R 3 P moieties are observed.

Synthesis and characterization of some aminoarsonium chlorides

Abstract R 3 As reacts with NR′R″Cl to give good yields of a new homologous series of aminoarsonium chlorides, [R 3 AsNR′R″]Cl, in which R = Me, Et, n-Pr, and Ph; R′ and/or R″ = H, Me. IR, NMR, mass, and X-ray spectral data suggest that the arsenic is tetra- coordinate. Electfical conductivity and temperature and concentration dependent NMR studies suggest that hydrogen-bonding interactions are important in solution. Quaternization of the arsenic produces a downfield 1 H NMR chemical shift for the protons in the alkyl chains and a change from non-equivalence to equivalence of the C-1 protons. The NMR data are compared with those for the analogous phosphorus compounds. The electron impact, chemical ionization, and negative ion mass spectral data and fragment ion identities are given for the compounds. Ions corresponding to a variety of AsCl containing species, in addition to those associated .with fragmentation of the R 3 As moieties, are observed in the EI mass spectra. AsN, AsNAs, and AsNAsN containing fragments are observed in the Cl mass spectra and AsCl bonding species in the NI mass spectra. A preliminary X-ray diffraction study of [n-Pr 3 AsNH 2 ]Cl indicates near tetrahedral geometry about the arsenic atom.

Aminoarsolanes—II. Conformational studies

Abstract 1H and 13C NMR spectra of six dialkylaminoarsolanes were obtained as a function of solvent, concentration, and temperature. CI mass spectral data were also obtained as a function of retention time for the same compounds. These results suggest that the AsN bond is not labile as compared to the AsCl bond in chloroarsolanes. No evidence for dimer formation was noted either in solution or the gas phase under the investigated experimental conditions. The averaged solution conformation of the 1,3-dioxarsolane ring is discussed in terms of rapid intramolecular conformational averaging; nature of substituents at the 2,4, and 5 positions; and effects of temperature, solute concentration and solvent type.

Determination of the bonding preference of borane (BH3) toward aminoarsines by multinuclear nuclear magnetic resonance spectroscopy

The reactions of BH3·thf (thf = tetrahydrofuran) with selected (dialkylamino)dimethylarsines, Me2AsNR2(R = Me, Et, Prn, or Pri) have been carried out as a function of temperature to determine the initial co-ordination site of boron and to elucidate the nature of any As–N, As–B, and N–B bond dissociation/formation processes in solution. The reactions were monitored by multinuclear (1H, 11B, and 13C) n.m.r. spectroscopy over a temperature range of –90 to 25 °C. With Me2AsNMe2, a N–B bonded adduct is formed at low temperature, which decomposes at 25 °C to yield (Me2NBH2)2, Me2NH·BH3, µ-Me2NB2H5, and Me2AsAsMe2. Equimolar amounts of As–B and N–B adducts are formed at low temperature when Me2AsNEt2 is reacted with BH3·thf. With increasing temperature, the As–B adduct converts to the N–B adduct, which subsequently decomposes at room temperature to µ-Et2NB2H5, Et2NH·BH3, (Et2NBH2)2, and Me2AsAsMe2. The reaction of Me2AsNPrn2 with BH3·thf yields more of the As–B adduct than of the N–B adduct at –90 °C, but the former rearranges to the latter on warming. Only the As–B adduct is formed in the reaction of Me2AsNPri2 with BH3·thf. These results suggest that the steric bulkiness of the R2N moiety plays an important role in determining the co-ordination site of the boron in this series of compounds.