Intra- and Intermolecular N−H···F−C Hydrogen-Bonding Interactions in Amine Adducts of Tris(pentafluorophenyl)borane and -alane

Abstract

The reaction between B(C(6)F(5))(3) and NH(3)(g) in light petroleum yielded the solvated adduct H(3)N.B(C(6)F(5))(3).NH(3). Treatment with a second equivalent of B(C(6)F(5))(3) afforded H(3)N.B(C(6)F(5))(3). Attempts to prepare the analogous alane adduct were unsuccessful and resulted in protolysis. Related compounds of the form R'R' 'N(H).M(C(6)F(5))(3) were synthesized from M(C(6)F(5))(3) and the corresponding primary and secondary amines (M = B, Al; R' = H, Me, CH(2)Ph; R' ' = Me, CH(2)Ph, CH(Me)(Ph); R'R' ' = cyclo-C(5)H(10)). The solid-state structures of 13 new compounds have been elucidated by single-crystal X-ray diffraction and are discussed. Each of the borane adducts has a significant bifurcated intramolecular hydrogen bond between an amino hydrogen and two o-fluorines, while N-H...F-C interactions in the alane adducts are weaker and more variable. (19)F NMR studies demonstrate that the borane adducts retain the bifurcated C-F...H...F-C hydrogen bond in solution. Compounds of the type R'R' 'N(H).M(C(6)F(5))(3) conform to Etter's rules for the prediction of hydrogen-bonding interactions.

Hydrogen and Amine Activation by a Frustrated Lewis Pair of a Bulky N‐Heterocyclic Carbene and B(C6F5)3

“…The adducts tBuNH 2 B(C 6 F 5 ) 3 , H 3 NB-(C 6 F 5 ) 3 and EtNH 2 B(C 6 F 5 ) 3 were prepared as previously described. [19,36] 1: A solution of B(C 6 F 5 ) 3 (0.100 g, 0.20 mmol) in toluene (5 mL) was cooled to À78 8C. IDipp (0.076 g, 0.20 mmol) was added to the cooled solution in toluene (9 mL) with a syringe.…”

Structural Characterization, Infrared Spectroscopy, and Theoretical Calculations for B(C6F5)3‐Stabilized Benzene–Ammonia and Benzene–Water Complexes

“…Figure 1 shows IR spectra for 2 and B(C 6 F 5 ) 3 ·NH 3 (for 1 and B(C 6 F 5 ) 3 ·H 2 O, see Supporting Information) in the N À H stretching region. In comparison to those of B(C 6 F 5 ) 3 ·H 2 O and B(C 6 F 5 ) 3 ·NH 3 , [12] the vibrational bands of the O À H and N À H bonds in 1 and 2 display considerable shifts to lower frequency of up to 87 cm À1 for 1 Figure 1. The NÀH stretching region of the IR spectra of B(C 6 F 5 ) 3 ·NH 3 and 2.…”

“…Single crystals of benzene complexes 1 and 2 were obtained by recrystallization of B(C 6 F 5 ) 3 ·H 2 O [11] and B-(C 6 F 5 ) 3 ·NH 3 [12] from benzene. The crystals are fragile and readily decompose under reduced pressure or on exposure in a dry box, which results in evaporative benzene loss.…”

“…[4b] To test this prediction in the solid state, recrystallization of B(C 6 F 5 ) 3 ·NH 3 [12] from toluene was carried out, and this afforded single crystals of B-(C 6 F 5 ) 3 ·NH 3 ·C 7 H 8 (7). The structure of 7 ( Figure 6) is similar to that of 2 but the N···centroid distance is about 0.075 shorter.…”

Syntheses, Crystal Structures and Properties of Two New Manganese(II) Coordination Polymers with Tetrafluorophthalate Ligands

“…The second is the steric hindrance effect that the fluorine atoms have on the torsion angle by which the carboxylate groups are twisted out of the plane of the benzene ring. Moreover, hostguest C-H···F and O-H···F contacts can be as important as C-H···O/C-H···N and O-H···O/O-H···N interactions in stabilizing a specific structure [25,26], and can be applied in crystal design. Encouraged by all that was mentioned above, we have chosen 3,4,5,6-tetrafluoro-benzene-1,2-dicarboxylic acid (1,2-…”