Structure cristalline et moléculaire de la glycocyamine

Abstract

Glycocyamine crystallizes in the monoclinic system P2x/c; a= 4.937, b = 6.004, c = 17-519/~; fl= 101-93 °. The structure was solved by the direct method. Counter data collected with Mo Ks radiation were used in the refinement. The final R value is 0"064 for 1504 observed reflexions. All the hydrogen atoms have been located on difference Fourier maps. The molecular structure corresponds to that of a zwitterion. It can be described as consisting of two groups of atoms lying on two planes which form an angle of 3-99 °. The average value of the three C-N bond lengths in the guanidyl group is 1.327 A. The molecules are held together by a network of hydrogen bonds.

Structure of guanidinomethylphosphonic acid monohydrate, C2H8N3O3P.H2O

“…ca 2°). The C-N lengths and N--C--N angles are in accord with those in the guanidino moieties of guanidinoacetic acid (Berthou, Laurent & Nakajima, 1976), fl-guanidinopropionic acid (Steward, Warner & Clarke, 1974) and y-guanidinobutyric acid hydrochloride (Maeda, Fujiwara & Tomita, 1972). The guanidino group is nearly planar.…”

On nitroguanidines. II. The structure of N-methyl-N'-nitroguanidine

“…The bonding distances reveal some interesting features. The formal double bond, C(1)-N(2), is 0.05 .A longer than the two other C-N bonds of the guanidine moiety, which are of approximately the same length as the C-N bonds in protonated guanidine moieties (Cotton, Day, Hazen & Larsen, 1973;Cotton, Day, Hazen, Larsen & Wang, 1974;Larsen, 1975;Berthou, Laurent & Nakajima, 1976;Bracuti, 1979), and only slightly longer than in the guanidinium ion (Adams & Ramdas, 1978). The nitrimino group closely resembles that in trimethylammonionitramidate (Cameron, Hair & Morris, 1972), where the zwitterionic structure is evident, and that in cyanonitramide, obtained from counting statistics modified for experimental instability.…”