Intermolecular Hydrogen Bonding between Water and Pyrazine

Abstract

Completely planar is the hydrogen-bonded complex of pyrazine and water (see sketch), which was obtained by supersonic expansion and investigated by rotational spectroscopy. The water molecule lies in the plane of the aromatic ring, and the lone pair of electrons on the nitrogen atom functions as the acceptor in the N⋅⋅⋅H-O hydrogen bond, not-as in the corresponding benzene complex-the π electrons.

Hydrogen bonding, structure, and dynamics of benzonitrile–water

“…Two nearly planar structures are proposed but the question of the position of the water hydrogens is still open. 5 This arrangement of the hydrogen bond is in agreement to what has been obtained for other complexes of water with some nitrogen containing aromatic molecules namely pyrazine-water, 6 pyrimidine-water, 7 and pyridazine-water. 8 In all three cases a N¯H-O bond is formed and the structure is distorted so as to achieve an antiparallel alignment of the dipole moments of the partner molecules.…”

“…4,5 The question of the position of the water hydrogens was left open because various possible structures are compatible with the observed rotational spectra. For this reason we analyzed various possible conformations and the influence of one of the leading energy terms which should single out the most stable configuration; namely the dipole-dipole interac- (8,10)Ϫ17 (7,11) 59934.86 18 (8,11)Ϫ17 (7,10) 59928.68 19 (8,11)Ϫ18 (7,12) 61549.51 19 (8,12)Ϫ18 (7,11) 61535.86 20 (8,13)Ϫ19 (7,12) 63125.67 21 (7,14)Ϫ20 (6,15) 60714.77 21 (7,15)Ϫ20 (6,14) 60013.12 21(8,13)Ϫ20 (7,14) 64750. 13 21(8,14)Ϫ20 (7,13) 64691.50 a These transitions are doubly overlapped because they are asymmetry degenerate K Ϫ1 doublets.…”

Intermolecular Hydrogen Bonding in 2-Fluoropyridine-Water

“…Depending on the symmetry of the partner molecule, the internal rotation of water along the HB may also connect two equivalent minima. This is the case of water complexes with pyridine (PYR, C 2v ), pyrazine ( D 2h ) and triazine ( D 3h ) . For lower symmetries of the partner molecule, such as pyrimidine or pyridazine, no tunneling splittings have been observed.…”

Hydrogen Bonding on Photoexcitation

“…Hydrogen bonding involving heteroaromatic rings such as azines, diazines, quinones, etc., is very important as it plays an important role in the structure and function of many biological systems [3,9,10]. Hydrogen bonding to molecules in their ground electronic state has been widely investigated by different spectroscopic [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] and theoretical [8,25,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] methods; however, much less is known about hydrogen bonding to molecules in their excited states.…”