Donald R. Martin

Borane adducts of some nitrogen heterocyclic compounds

Abstract The borane adducts of quinoline, isoquinoline, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, and aniline were prepared by the interaction of each Lewis base with dimethylsulfideborane. The IR, 1 H NMR and 11 B NMR spectra have been used to characterize these derivatives. A detailed examination of the IR and NMR spectra of the aminopyridineboranes has established that the BH 3 group is coordinated with the pyridyl nitrogen. The 1 H NMR and 11 B NMR chemical shifts indicate the presence of extensive intramolecular hydrogen bonding in 2-aminopyridineborane and some intermolecular hydrogen bonding in 4-aminopyridineborane.

Borane and monoiodoborane derivatives of some bis(diphenylphosphino)alkanes

Abstract A series of borane and monoiodoborane derivatives of bis(diphenylphosphino)alkanes. (C6H5)2P (CH2)nP(C6H5)2 in which n has values of 2 through 4 has been synthesized. Only compounds with the formulae [(C6H5)2P]2(CH2)n · (BH3)2 and (C6H5)2P]2CH2)n · BH2I were isolable, the latter being boronium iodides. The compounds were characterized by their melting points, elemental analyses, molar conductivities, infrared spectroscopy, and 1H and 11B nuclear magnetic resonance spectroscopy. The relationship between the length of the carbon chain and the 11B NMR chemical shift is discussed.

Synthesis of carboxylic acid derivatives of triphenylphosphine cyanoborane

Abstract Alkylation of triphenylphosphine-cyanoborane, Ph 3 P·BH 2 CN, with Et 3 OBF 4 gave an N-ethylnitrilium salt which was converted to new phosphine-borane derivatives, Ph 3 P·BH 2 X (X = COOH, C(O)N(H)Et, and COOEt). Characterization data from IR, 1 H and 11 B NMR spectroscopy and elemental analyses are reported.

Reactions of cyanotrihydroborate ion and its derivatives with halogens

Abstract The addition of an equivalent of Cl 2 , Br 2 or I 2 to a solution of Na[H 3 BCN] in glyme (1,2-dimethoxyethane) yields the cyanoborane cyclic oiligomers previously reported. The addition of an excess of a Lewis base (e.g. a pyridine, a tertiary amine or a tertiary phosphine) to the cyanoborane yields a cyanoborane adduct, LBH 2 CN. The addition of an excess of chlorine yields a solution believed to contain [glyme]-BH 2 CN. This solution reacts slowly with Lewis bases (L) to yield LBH 2 CN, and small amounts of chlorinated cyanoborane adducts. The proportion of chlorinated products relative to LBH 2 CN increases as the amount of moisture in the reaction mixture increases and as the base strength of L is reduced. The chlorination of LBH 2 CN in moist benzene yields LBCl 2 CN as the principal product when L is pyridine, while a complex misture is obtained when L = (C 2 H 5 ) 3 N.

The preparation of tellurium perfluoroalkyls by photolysis of dimethyltelluride in the presence of perfluoroalkyl iodides

The following new compounds containing perfluoroalkyl-tellurium linkages have been synthesized: CH3TeCF3, (CF3)2Te, CH3TeC2F5, (C2F5)2Te. These preparations were brought about by the photochemical interaction of (CH3)2Te and an appropriate perfluoroalkyl iodide in a vycor tube at 310 nm wavelength. The resulting mixture of tellurides, RfTeCH3 and (Rf)2Te in which Rf = CF3 or C2F5, cannot be separated by trap-to-trap distillation, but the relative amounts of each product were determined by 19F NMR spectroscopy. The clear yellow tellurides are air stable, but yield either CF3H or C2F5H on basic hydrolysis. No reaction was noted with CH3Cl up to 80°, but at 215° a mixture of CH3TeCF3 and (CF3)2Te interacted with benzyl chloride to give C6H5CH2CF3 in a 3·4 cent yield.

The preparation of some new boron trihalide addition compounds with trimethylarsine and trimethylstibine

New 1 : 1 adducts of BBr3 and BI3 with (CH3)3As and (CH3)3Sb are reported. The (CH3)3As adducts are stable indefinitely at room temperature under an inert atmosphere while the (CH3)3Sb compounds slowly decompose at that temperature to form (CH3)3SbX2 (X = Br, I). Boron-11 and proton NMR data suggest that these species may exist as ions in chloroform solution.

Synthesis, characterization and halogenation of some dihydroboron(1+) salts containing phosphine bases

Abstract Several dihydroboron(1+) cations of the types LYBH 2 + and YY′BH 2 + in which L is an amine, Y is a phosphine, and Y′ is a different phosphine were synthesized and characterized. A cyclic dihydroboron(1+) salt containing 1,2-bis(diphenylphosphino)ethane was also prepared and characterized. The PF 6 − salts and their chlorination products were studied via proton and boron NMR and IR data. Several asymmetric cations of the types LYBHCl + and YY′BHCl + are reported. The bound phosphine P(CH 3 ) 2 C 6 H 5 was found to have nonequivalent methyl resonances in the proton NMR spectra of the cations [(CH 3 ) 3 NBHClP(CH 3 ) 2 C 6 H 5 ] + and [(C 6 H 5 ) 3 PBHClP(CH 3 ) 2 C 6 H 5 ] + which confirms the asymmetric nature of the boron atoms in these two cations.

Synthesis of trimethylphosphine

Abstract An improved synthesis of trimethylphosphine from the reaction of phosphorus trichloride with methyl lithium is presented. Yields of 60 per cent are obtained at −78°. This synthesis employs a simplified procedure to give higher yields than are realized with the methyl Grignard reagents.

Borane and tribromoborane adducts of some 2-substituted pyridine compounds

The borane and tribromoborane adducts of 2-bromopyridine, 2-chloropyridine, 2-fluoropyridine, and 2-cyanopyridine were successfully prepared, except in the case of the reaction between BBr3 and 2-cyanopyridine in which an insertion reaction gave bromo-(2-pyridyl)methylideneaminodibromoborane. The m.p., IR, 1H NMR and 11B NMR spectra of all compounds prepared are reported. An evaluation of the electronegativity and steric effects of the pyridine substituent in relation to the donor-acceptor strength of the dative bond has been made along with a discussion of the change in the electron density occurring within the pyridine ring system.

An investigation of lewis base-monoiodoboranes and their reactions with group V donors in solution

Abstract A series of monoiodoborane adducts LBH 2 I (L = N(CH 3 ) 3 pyridine, 3-methylpyridine, 4-methylpyridine or (C 6 H 5 ) 3 P) has been prepared. Ideally, the addition of suitable amines, phosphines or trimethylarsine to a benzene solution of these adducts would be expected to yield boronium salts containing two different donors coordinated to a central boron atom. These salts, of the general formula LL′BH 2 I, were formed in several instances (L′ = (CH 3 ) 3 P, (C 6 H 5 ) 3 P, (CH 3 ) 3 N). Six previously unreported boronium cations have been characterized. The iodide salts of these boronium cations may be easily converted to their hexafluorophosphate analogs except for the large ligands such as (C 6 H 5 ) 3 P or 3-methylpyridine. In contrast, trimethylarsine reacted with 4-MepyBH 2 I in benzene to give 4-MepyH + I − and [(CH 3 ) 3 AsI] + I − . The proton and boron NMR spectra of all species were investigated when experimentally feasible.