Abstract
The title structures, [Zn2(C3H6NS2)4(C14H14N4O2)]·2C3H7NO (I) and [Zn2(C7H14NS2)4(C14H14N4O2)] (II), each feature a bidentate, bridging bipyridyl-type ligand encompassing a di-amide group. In (I), the binuclear compound is disposed about a centre of inversion, leading to an open conformation, while in (II), the complete mol-ecule is completed by the application of a twofold axis of symmetry so that the bridging ligand has a U-shape. In each of (I) and (II), the di-thio-carbamate ligands are chelating with varying degrees of symmetry, so the zinc atom is within an NS4 set approximating a square-pyramid for (I) and a trigonal-bipyramid for (II). The solvent di-methyl-formaide (DMF) mol-ecules in (I) connect to the bridging ligand via amide-N-H⋯O(DMF) and various amide-, DMF-C-H⋯O(amide, DMF) inter-actions. The resultant three-mol-ecule aggregates assemble into a three-dimensional architecture via C-H⋯π(pyridyl, chelate ring) inter-actions. In (II), undulating tapes sustained by amide-N-H⋯O(amide) hydrogen bonding lead to linear supra-molecular chains with alternating mol-ecules lying to either side of the tape; no further directional inter-actions are noted in the crystal.
Highlights
The title structures, [Zn2(C3H6NS2)4(C14H14N4O2)]Á2C3H7NO (I) and [Zn2(C7H14NS2)4(C14H14N4O2)] (II), each feature a bidentate, bridging bipyridyl-type ligand encompassing a di-amide group
In each of (I) and (II), the dithiocarbamate ligands are chelating with varying degrees of symmetry, so the zinc atom is within an NS4 set approximating a square-pyramid for (I) and a trigonal-bipyramid for (II)
In (II), undulating tapes sustained by amide-N—HÁ Á ÁO(amide) hydrogen bonding lead to linear supramolecular chains with alternating molecules lying to either side of the tape; no further directional interactions are noted in the crystal
Summary
The potential of self-association between amide functionalities via amide-N—HÁ Á ÁO(amide) hydrogen-bonding has long been recognized (MacDonald & Whitesides, 1994) In this way, eight-membered {Á Á ÁHNCO}2 synthons can be formed. Extended aggregation patterns based on a single point of contact repeat associations leading to supramolecular chains or double-connections (edge-shared) leading to tapes In this connection, isomeric di-amide structures of the general formula (n-NC5H4)CH2N(H)C( O)—C( O)N(H)CH2(C5H4N-n), for n = 2, 3 and 4, hereafter abbreviated as nLH2, have long attracted interest for their potential to form supramolecular tapes. A similar coordination/hydrogen-bonding arrangement is found in the three-dimensional assembly in crystals of {[Cu(3LH2)2Br]ÁBrÁH2O}n (Zeng et al, 2008) Motivated by these results, investigations were commenced exploring the coordination ability of nLH2 with zinc(II) dithiocarbamates functionalized with hydrogen-bonding potential, i.e. Zn[S2CN(R)CH2CH2OH]2, for R = alkyl, CH2CH2OH. Zn—S1 Zn—S2 Zn—S3 Zn—S4 Zn—N3 C1—S1 C1—S2 Cn—S3 Cn—S4 Cm—O1 Cm—N4 Cm—Cmi S1—Zn—S3 S2—Zn—S4
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