Acta Crystallographica Section B

Structural Science

Volume 52, Part 6 (December 1996)

research papers

Acta Cryst. (1996). B52, 989-998 [ doi:10.1107/S010876819600451X ]

Inclusion compounds of thiourea and peralkylated ammonium salts. III. Hydrogen-bonded host lattices built of thiourea and nitrate ions

Q. Li and T. C. W. Mak

Abstract: The new inclusion complexes tetraethylammonium nitrate-thiourea (1:3), (C₂H₅)₄N⁺.NO₃^-. 3(NH₂)₂CS (1), tetra-n-propylammonium nitrate-thiourea-water (1:3:1), (n-C₃H₇)₄N⁺.NO₃^-.3(NH₂)₂CS.H₂O (2), tetramethylammonium nitrate-thiourea (1:1), (CH₃)₄N⁺.NO₃^-.(NH₂)₂CS (3), tetra-n-propylammonium nitrate-thiourea (1:1), (n-C₃H₇)₄N⁺.NO₃^-. (NH₂)₂CS (4), and tetra-n-butylammonium nitrate-thiourea (1:1), (n-C₄H₉)₄N⁺.NO₃^-.(NH₂)₂CS (5) have been prepared and characterized by X-ray crystallography. Crystal data, Mo K [alpha] : (1), space group P ${\bar 1}$ , a = 10.300 (2), b = 14.704 (3), c = 15.784 (4) Å, [alpha] = 75.30 (3), = 86.98 (3), [gamma] = 72.25 (3)°, Z = 4 and R_F = 0.039 for 5034 observed data; (2), space group P2₁/n, a = 8.433 (2), b = 9.369 (2), c = 34.361 (7) Å, = 91.01 (3)°, Z = 4 and R_F = 0.050 for 2475 observed data; (3), space group Pnma, a = 15.720 (3), b = 8.218 (2), c = 8.709 (2) Å, Z = 4 and R_F = 0.073 for 579 observed data; (4), space group P2₁/n, a = 8.784 (2), b = 14.421 (3), c = 15.078 (3) Å, = 92.31 (3)°, Z = 4 and R_F = 0.046 for 2507 observed data; (5), space group Pna2₁, a = 19.934 (3), b = 12.680 (2), c = 9.092 (3) Å, Z = 4 and R_F = 0.047 for 1646 observed data. In the crystal structure of (1) infinite chains each composed of an alternate arrangement of a twisted thiourea trimer and a nitrate ion are cross-linked to form a puckered layer and further hydrogen bonding between such layers leads to a channel host framework for accommodation of the cationic guests. In the crystal structure of (2) two independent thiourea molecules are used to construct a hydrogen-bonded puckered layer normal to the c axis, whereas the remaining thiourea molecule, together with the nitrate ion and water molecule, generate another puckered layer that is parallel to the first. Hydrogen bonding between these two types of layers gives rise to a channel system running parallel to the [100] direction and the cations are stacked regularly within each column. Compounds (3), (4) and (5) have closely related crystal structures in which the cations are separated by one-dimensional, infinitely extended thiourea-nitrate composite ribbons in a sandwich-like packing arrangement.