Refinement of the crystal structure of aquazinc(II) glutamate hydrate, Zn(H2O)(C5H7NO4) · H2O

Abstract

C5H11NO6Zn, orthorhombic, P212121 (no. 19), a = 7.1770(6) A, b = 10.3960(9) A, c = 11.1210(9) A, V = 829.8 A, Z = 4, Rgt(F) = 0.018, wRref(F) = 0.043, T = 173 K. Source of material Good quality colorless crystals of zinc-glutamate-MOF (MOF = metal organic framework) were obtained from a solution of Lglutamic acid potassium salt monohydrate (5.00 g, 24.61 mmol) and zinc acetate tetrahydrate (5.40 g, 24.61 mmol) in water (100 mL) by slow evaporation of water. Experimental details The H atoms bonded to the N and O atoms were located and refined due to their importance in the hydrogen bonding pattern, the otherHatomswere calculated usingC—Hdistances of 0.99A. Discussion The structure of the title compound, determined by film method, was published in 1966 (cell dimensions of a = 11.190(2) A, b = 10.463(1)A and c=7.220(2)Awith a finalR1 value of 0.032) [1]. Re-determination using image plate techniques (a = 11.121(9)A, b = 10.396(9) A and c = 7.177(6) A) let to lower R values. The quality of the data allowed the determination of the positions of H atoms of the chemisorbed water molecules. The zinc atom is coordinated in a distorted octahedral fashion. The O3 atom and the O4 atom (zinc bonded water molecules) coordinate the zinc in cisoid axial positions. The crystal structure also consists of another (chemisorbed) water molecule (O6, HO1, HO2). The water molecules give rise to hydrogen bonding. The zinc bonded water (O4, HO3, HO4) is coordinated in a trigonal planar fashion by Zn1 (d(Zn1—O4) = 2.059 A) and two hydrogen bonds to two chemisorbed water molecules with O4···O6 distances of 2.704 A and 2.745A, respectively. The chemisorbed water is coordinated furthermore via hydrogen bonding byO1 andO2 from the carboxylic groups of two different symmetry-relatedmolecules in a tetrahedral fashion.Another group that gives rise to hydrogen bonding is the amino group. It forms a hydrogen bondwith the O3 atom of a neighboring molecule (d(Namino···O3) = 2.942 A). Z. Kristallogr. NCS 223 (2008) 55-56 / DOI 10.1524/ncrs.2008.0026 55 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: colorless prism, size 0.21 × 0.29 × 0.38 mm Wavelength: Mo K4 radiation (0.71069 A) *: 29.59 cm−1 Diffractometer, scan mode: Stoe IPDS II, ./6 2%max: 51.18° N(hkl)measured, N(hkl)unique: 11307, 1564 Criterion for Iobs, N(hkl)gt: Iobs > 2 #(Iobs), 1520 N(param)refined: 138 Programs: SIR97 [2], SHELXL-97 [3] Table 1. Data collection and handling. H(2A) 4a 0.2121 0.8764 0.1806 0.024 H(2B) 4a 0.3481 0.9968 0.1980 0.024 H(3A) 4a 0.3797 0.7597 0.3257 0.021 H(3B) 4a 0.5123 0.8808 0.3487 0.021 H(5) 4a 0.6584 0.7229 0.2277 0.018 HN(1) 4a 0.687(4) 0.959(3) 0.184(2) 0.030(8) HN(2) 4a 0.801(5) 0.871(3) 0.134(2) 0.025(7) HO(1) 4a 0.405(5) 0.882(3) 0.549(3) 0.040 HO(2) 4a 0.477(5) 0.879(3) 0.643(3) 0.040 HO(3) 4a 0.779(5) 1.143(3) 0.011(3) 0.040 HO(4) 4a 0.652(4) 1.178(3) −0.051(3) 0.040 Table 2. Atomic coordinates and displacement parameters (in A). Atom Site x y z Uiso