LOCATION OF THE PROTON IN THE VERY STRONG OHO HYDROGEN-BONDS IN -(N,N-DIETHYLAMINO-N-OXYMETHYL)-4,6-DICHLOROPHENOL - A SINGLE-CRYSTAL NEUTRON-DIFFRACTION STUDY
H. Ptasiewiczbak et al., LOCATION OF THE PROTON IN THE VERY STRONG OHO HYDROGEN-BONDS IN -(N,N-DIETHYLAMINO-N-OXYMETHYL)-4,6-DICHLOROPHENOL - A SINGLE-CRYSTAL NEUTRON-DIFFRACTION STUDY, Zeitschrift fur Kristallographie. New crystal structures, 212(2), 1997, pp. 126-129
The crystal structure of -(N,N-diethylamino-N-oxymethyl)-4,6-dichlorop
henol contains two slightly different molecules A and B, both with ver
y strong intramolecular O ... H ... O hydrogen bonds, with O-O distanc
es 2.423(4) Angstrom and 2.400(5) Angstrom, respectively, and with no
crystallographic symmetry. The bridging oxygen atoms are also chemical
ly different, O1 is bonded to carbon and O2 to nitrogen. The single cr
ystal neutron diffraction study shows quite unambiguously that the pro
ton in both cases is located slightly off-centred. In the A molecule O
1-H = 1.167(6) Angstrom, H-O2 = 1.258(6) Angstrom and the angle O-H-O
= 175.8(5)degrees; in the B molecule O1-H = 1.186(7) Angstrom, H-O2 =
1.214(7) Angstrom and the angle O-H-O = 176,5(5)degrees, As expected t
he proton is thus closer to the centre in the slightly shorter hydroge
n bond.