Nucleic acid constituents part 9 the crystal and molecular structure of 2 n methyl guanosine mono hydrate
De-Graaff, R.A.G.; Martens, F.B.; Romers, C.
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry 34(10): 3012-3015
Crystals of 2-N-methylguanosine monohydrate, C11H15N5O5.H2O are triclinic with space group P1 and Z = 1. The lattice constants at 20.degree. C are a = 5.012 (2), b = 7.434 (6), c = 10.076 (7) .ANG., .alpha. = 96.18 (6), .beta. = 101.08 (6) and .gamma. = 113.60 (6).degree. Using Mo K.alpha. radiation 1387 significant reflexions were measured at room temperature with a 3-circle diffractometer. The structure was solved by Patterson methods and refined by least squares (Rw = 3.06%). The guanine base is syn-oriented (.chi. = -114.9.degree.) with respect to the sugar. The ribose ring has a S-type [C(2')-endo] conformation with pseudorotation angle P = 168.0.degree. and .phi.max 36.4.degree. The exocyclic C(5')H2-O(5')H moiety has a trans-gauche (g-) orientation with respect to O(1') and C(3'). The molecules are stacked along  and the packing is determined by H-bonds.