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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.

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.

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.

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.

A series of monohalo- and monopseudohalo-broane adducts LBH 2 X, (L = pyridine, (CH 3 ) 3 N, (CH 3 ) 3 P; X = F, Cl, Br, I, NCS, NCSe) has been prepared and characterized. A correlation was made between the boron-hydrogen coupling constant ( J BH ), the electronegativity of X ( E x ) and the estimated B-X bond distance ( D x ). For L = (CH 3 ) 3 N, J BH = 3·336 E x + 36·426 D x + 47·233, while for L = pyridine, J BH = 34·583 E x + 18·116 D x − 10·328. There was negligible change in J BH in the (CH 3 ) 3 PBH 2 X series.