Structural studies of organoboron compounds. XXX. 1,9-Dimethyl-3,5,7-triphenyl-2,4,6,8-tetraoxa-1,9-diazonia-5-bora-3,7- diboratatricyclo[5.4.0.0^3,9]undecane

Abstract

. Can. J. Chem. 66,1117Chem. 66, (1988. Details of the preparation and physical properties of the title compound are given. Crystals of 1,9-dimethyl-3,5,7-triphenyl- [Traduit par la revue]

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

“…In the ( s p 2 )~U~( s p 3 ) anhydridic moiety, the characteristic difference between the very short (sp2)~--0 bond (1.331(2) and 1.329(2) A) and the long (sp3)~--0 bond (1.472(2) and 1.468(2) A) is consistent with that observed for other compounds of type 2 (2), 4 (4), and similar cyclic "pyroboronates" involving one trigonal boronate and one tetracoordinated borinic (1 3) or boronic acid group (14)(15)(16)(17).…”

“…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). The sum of the bond lengths about the boron atom in 11, 6.170 A, is at the lower end of the range 6.19 1-6.297 A observed previously for compounds of the type " P~B O~N ( S~~) " (15,20).…”

“…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). The sum of the bond lengths about the boron atom in 11, 6.170 A, is at the lower end of the range 6.19 1-6.297 A observed previously for compounds of the type " P~B O~N ( S~~) " (15,20). This is consistent with a relatively low overall strain about the boron atom (15).…”

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

“…In the present case the short B-C bond is balanced by a relatively long N-B bond. The (sp3)~-C(phen 1) bond length in the phenylboronate compleg 6 (6) of 1.591 1 lies within the range of 1.582 to 1.633 A reported for (sp3)B-C(pheny1) distances in other phenylboronate complexes (17)(18)(19)(22)(23)(24)(25)(26)(27)(28).…”

“…This leads to increased s-character in the hybrid orbital at boron involved in the B-C bond and hence a shorter bond distance. As discussed in an earlier paper (22), the sum of all four bonds to boron in tetrahedral "PhB02N" compounds remains essentially constant. In the present case the short B-C bond is balanced by a relatively long N-B bond.…”