Structural studies of organoboron compounds XLVIII. 1,4-Diphenyl-3,3:6,6-bis(tetramethylene)-2,5,7-trioxa-3,6-diazonia-1,4-diboratabicyclo[2.2.1]heptane

Abstract

The reaction of N-hydroxypyrrolidine with either oxybis(dipheny1borane) or phenylboronic acid gives 1,4-diphenyl-3,3:6,6-bis(tetrarnethylene)-2,5,7-trioxa-3,6-diazonia-l,4-diboratabicyclo~2.2. llheptane in moderate yield. Crystals of the product are orthorhombic, a = 10.984(2), b = 14.619(2), c = 12.31 l(2) A, Z = 4, space group Pccn. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.039 and R, = 0.043 for 908 reflections with I r 3 4 4 . This is the first heterocyclic Mots cl6s : systkme cyclique 2,5,7-trioxa-3,6-diazonia-l,4-diboratabicyclo[2.2. llheptane, structure cristalline, compost5 organobore.[Traduit par la redaction]

TriphenylboroxinN,N-diethylhydroxylamine adduct (dimethylformamide solvate)

“…Also, an isomeric complex, (II), containing the O±B-coordinated N,N-diethylhydroxylamine in its N-oxide form, is suggested by already established structures of O±B-coordinated boron complexes of N-mono-alkylhydroxylamines (Kliegel et al, 1992(Kliegel et al, , 1992a and N,Ndialkylhydroxylamines (Kliegel et al, 1992b). The BOBON ring part in the alternative structure, (III), formed by twofold N±B/O±B coordination of the hydroxylamine to the boroxin ring, is reminiscent of the BOBON heterocyclic ring part in the bicyclic compounds from N,N-dialkylhydroxylamines and phenylboronic acid (Kliegel et al, 1991(Kliegel et al, , 2002. The X-ray analysis, however, reveals that none of these three molecular constitutions (I)±(III) is realised, but rather the structure (IV), a dimethylformamide solvate of an N,N-diethylhydroxylamine triphenylboroxin O±B adduct.…”

An O-bridged BONBON ring system (phenol adduct)

“…The crystal structure of (III) consists of a boron-containing heterocycle and a phenol molecule. The structure of the heterocycle has already been determined in crystals of the parent compound (without the phenol) (Kliegel et al, 1991). In the parent crystal, the molecule lies on a crystallographic C 2 axis; in the phenol adduct crystal the heterocycle is in a general position, but still has approximate C 2 symmetry (Fig.…”

Structural studies of organoboron compounds. LVI. 1-Benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane and 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1.12,6]dodecane

“…The chiral centres of the molecule depicted in Fig. 1 anellations (one at each side of the central BONBON ring) (9) and two other types of bridged BONBON compounds 13 (15) and 14 (19) are known. The tricyclic ring system of 13 has an 0-B-0 bridge across the B+N-B fragment and a C -C bridge across the N -B U N fragment of the central BONBON ring.…”

“…pounds like 2 (R' = R' = Me, R3 = R4 = H) (1.688(2) A) (2) and the "BONBON" derivative 14 (1.703(3) A) (19), but is somewhat shorter than the N-B bonds in other tetrahedral "PhBO,Nn compounds having sterically hindered N-B bonds like 4 (R = Me) (1.729(3) and 1.736(3) A) (4) and 7 (1.737(2) and 1.762(2) A) (this work) and similar bicyclic systems with N-B bond lengths ranging from 1.706(2) to 1.759(3) A (14,16,17). Shorter N-B bonds than those in the BONBON dimer 11 are found in the polycyclic BONBON compounds 12 (mean 1.586(3) A) (9) and 13 (mean 1.654(8) A) (15).…”