New Inclusion Compounds of Selenourea with Tetraethyl- and Tetra-n-propylammonium Halides

Air-sensitive selenourea inclusion complexes tetraethylammonium chloride–selenourea (1/2), (C2H5)4N⁺.C1⁻.2[(NH₂)₂CSe] (1), tetra-n-propyl-ammonium chloride–selenourea (1/3), (n-C₃H₇)₄N⁺.C1⁻.3[(NH₂)₂CSe] (2), tetra-n-propylammonium bromide–selenourea (1/3), (n-C3H₇)₄N⁺.Br⁻.3[(NH₂)₂CSe] (3), and tetra-n-propylammonium iodide–selenourea (1/1), (n-C₃H₇)₄N⁺.I⁻.(NH₂)₂CSe (4), have been prepared and characterized by X-ray crystallography. Crystal data, Mo Kα radiation: (1), space group P2₁/n, Z = 4, a = 8.768 (5), b = 11.036 (6), c = 19.79 (1) Å, β = 96.92 (1)°, R_F = 0.055 for 1468 observed data; (2), space group Cc, Z = 4, a = 18.091 (4), b = 13.719 (3), c = 11.539 (2) Å, β = 111.93 (3)°, R_F = 0.051 for 1187 observed data; (3), space group Cc, Z = 4, a = 18.309  (4), b = 13.807 (3), c = 11.577 (2) Å, β = 112.45 (3)°, R_F = 0.049 for 1592 observed data; (4), space group P2₁/n, Z = 4, a = 8.976 (1), b = 14.455 (2), c = 15.377 (3) Å, β = 94.16(1)°, R_F = 0.062 for 1984 observed data. In the crystal structure of (1) the parallel alternate arrangement of selenourea–chloride ribbons and selenourea chains generates a puckered layer and the cations are sandwiched between them. In the isomorphous complexes (2) and (3) wide selenourea–halide double ribbons are crosslinked by bridging selenourea molecules via N—H...Se and N—H...X hydrogen bonds [average N...Se = 3.521 (8) and 3.527 (7), N...Cl = 3.354 (8) and N...Br = 3.500 (7) Å in (2) and (3), respectively] to form a channel-like three-dimensional network and the cations are accommodated in a single column within each channel. In the crystal structure of (4) the selenourea molecules are joined in the shoulder-to-shoulder fashion via N—H...Se hydrogen bonds [N...Se = 3.529 (7) and 3.534 (7) Å] to generate a ribbon and each selenourea molecule also forms a pair of chelating N—H...I hydrogen bonds [N...I = 3.567 (7) and 3.652 (7) Å] to an adjacent iodide ion.

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