Structural and spectroscopic studies of dipotassium 3,3,3′,3′-tetramethylcystinate trihydrate, K₂[C₁₀H₁₈N₂O₄S₂]3H₂O

Abstract

127 (1984). The compound dipotassium 3,3,3',3'-tetramethylcystinate trihydrate, K2 [CII,H,,0,N2S2]3H20, has been prepared and characterized by single crystal X-ray diffraction. Crystals were monoclinic, P 2 , , n = 6.160(1), b = 26.473(8), c = 6.193(1) A, P = 113.94(1)", with two formula units in the unit cell. Intensities were measured on a Syntex P2[ diffractometer with use of MoKa radiation. The structure was solved by standard methods and refined to RI = 0.0469, R2 = 0.0472 based on 2303 independent observed reflections. The C-S bonds (1.877(6), 1.891(6) A) are longer than in many similar compounds although the S-S bond (2.040(2) A) is not. The C-S-S-C torsional angle (108.7(3)") is larger than normal in dithiol compounds. Other distances and angles are normal. Two types of potassium coordination are present, one a distorted octahedron, the other a distorted trigonal prism. In addition to the ionic interactions, hydrogen bonds involving the water molecules are important in stabilizing the structure. (108,7(3)") est plus grand que ceux observts normalement dans les dithiols. Les autres distances et les autres angles sont normaux. Le potassium posskde deux types de coordination, I'un est un octakdre deform6 tandis que I'autre est un prisme trigonal dCformC. En plus des interactions ioniques, les liaisons hydrogknes impliquant les molCcules d'eau sont importantes pour de la stabilitC de la structure.[Traduit par le journal]

(S)-2,2,5,5-Tetramethylthiazolidine-4-carboxylic acid: a compound which exists in the amino acid rather than the zwitterion form

“…The angles for 1 of 26.4(7) and 23.7(6)" are considerably larger than normal. Large angles have been observed previously in penicillamine (19) and its derivatives (20,21) and have been explained in terms of non-bonding steric interactions. Similar interactions of the carboxylate group and the 5-methyl groups appear to be present here.…”

Synthesis and crystal structure of the novel metal organic framework Zn(C3H5NO2S)2

“…Atomic coordinates of all atoms were included in the refinement but, to ensure the convergence of the process, restraints on bond lengths and angles were introduced, thus limiting the number of free parameters. The values for the bond lengths and angles were taken from similar molecules and molecular fragments found on the Cambridge Structural Database (Allen, 2002) [codes: BIKWIB (Menger and Caran, 2000, COJTUQ (Faggiani et al , 1984), CUPENS (Thich et al , 1974), CYSENC10 (Tucker, 1979), CYSTBR (Anbuchezhiyan et al , 2010), LCYSTI10 (Oughton and Harrison, 1959), and NURHEO (Seko et al , 2010)] and the standard deviations of the values assigned to bonds and angles were 0.02 Å and 1°, respectively. Two different isotropic temperature factors were introduced for the structure refinement, one for C, O, N, and S atoms and other one for the Zn atom.…”

A crystallographic titration of the dipeptide L-isoleucyl-L-isoleucine

“…This crystal structure was only the second with a peptide anion, the ®rst being (R)-phenylglycyl-(R)-phenylglycine [in the (S)-1-phenylethylamine salt (Akazome et al, 1997)]. Even for simple amino acids, structural information on anions is very limited indeed; Tl + Ádl-Cys À (Freeman & Moore, 1977) and Na + Á3,5-dinitro-l-Tyr À ÁH 2 O (Cody et al, 1979) are the only monoanions, while dianions have been obtained for Ca 2+ Ál-Glu 2À Á3H 2 O (Einspahr & Bugg, 1974) and 2K + Á3,3,3 H ,3 H -tetramethyl-d-cystine 2À Á3H 2 O (Faggiani et al, 1984).…”