Mixed Boron Trihalide Adducts. A Nuclear Magnetic Resonance Study of Halogen Redistribution in Adducts of Trimethylphosphine, Trimethylphosphine Oxide, and Trimethylphosphine Sulfide

Abstract

Halogen redistribution in the sparingly soluble boron trihalide adducts of Me3P, Me3PO, and Me3PS gives mixed boron trihalide adducts of these bases. Only small proportions of the fluorine-containing mixed boron trihalide adducts are present at equilibrium in the Me3PS adduct system, in accord with previous studies of adducts of other sulfur donors. The effects of the donor on F,Cl and F,Br halogen redistribution are discussed.

Systematics of BX3 and BX2+ Complexes (X = F, Cl, Br, I) with Neutral Diphosphine and Diarsine Ligands

“…These two complexes serve as useful models for the bidentate diphosphine and diarsine complexes described below. [BF 3 (PMe 3 )] has been studied on several occasions, , and our spectroscopic data are in good agreement; however, its structure has not been reported previously. Colorless crystals of [BF 3 (PMe 3 )] [ 1 ], which decomposed rapidly in air, were obtained by layering a CH 2 Cl 2 solution containing [BF 3 (SMe 2 )] and PMe 3 in a 1:1 molar ratio with n -hexane.…”

Trivinylphosphineborane (CH2CH)3PBH3 and related compounds

“…The set of trimethylphosphine complexes is a representative example in case: While the adducts with BCl 3 , BBr 3 and BI 3 could be crystallized and their structures determined, the BF 3 adduct was found to undergo rapid dissociation into its components on attempted crystallization. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] It is therefore the more noteworthy that in the present work crystallization of the homologous (Et 3 P)BF 3 was successful.…”

Urea – boron trihalide adducts. IV. Ionic–covalent equilibria in the tetramethylthiourea–BF3 and tetramethylselenourea–BF3 systems and the influence of B2F7− formation

“…When equal amounts of fluorine and chlorine were present much of the fluorine appeared to be present in BF4-and BF3C1-, suggesting that the neutral and cationic species are enriched in chlorine. The nonrandom distribution of fluorine and chlorine at equilibrium is not surprising in view of other studies of sulfur-donor adducts (11)(12)(13). The remaining 19F peaks in the TMTU-BF3-BC13 system are tentatively assigned t o TMTU.BF2C1 and TMTU.BFCI2 as in Table 1, although (TMTU)zBFCI+ cannot be excluded at present.…”

“…(ii) The absence of a separate free TMTU peak when excess TMTU is present indicates a rapid breaking and reforming of the donor-acceptor bond, as has been observed with other sulfur donors (11)(12)(13), and this reaction provides an additional mechanism whereby BF3 could interchange rapidly between cis and trans positions. (iii) l H coalescence temperatures for cis-tratzs isomerization of BF3 about C=O in ketone.BF3 adducts can be as low as -120 "C (30), well outside the temperature range studied in the present work.…”