Chong-Qing Wan

Supramolecular frameworks assembled via intermolecular lone pair-aromatic interaction between carbonyl and pyridyl groups

Four types of unconventional intermolecular CO⋯π interactions between carbonyl and pyridyl moieties are identified in the construction of two supramolecular frameworks from mononuclear Cu(II) building blocks.

Intermolecular S··π interactions in crystalline sulfanyl-triazine derivatives

Three types of intermolecular S⋯π interaction geometry are identified in the crystal structures of four sulfanyl-triazine derivatives bearing pendant heterocyclic rings, in which the triazinyl, pyrazinyl, pyrimidinyl and pyridyl rings are found to exhibit different affinities for the divalent S atom.

Ancillary Ligands and Spectator Cations as Controlling Factors in the Construction of Coordination and Hydrogen‐Bonded Networks with the tert‐Bu‐CC⊃Agn (n=4, 5) Supramolecular Synthon

Supramolecular networks constructed with the tBu--C[triple bond]C superset Ag(n) (n=4 or 5) metal-ligand synthon and trifluoroacetate have been transformed through the introduction of ancillary terminal nitrile ligands, from acetonitrile through propionitrile to tert-butyronitrile, giving rise to a 2D coordination network in AgC[triple chemical bond]CtBu3 AgCF(3)CO(2)H(2)O (1), a 2D hydrogen-bonded network in AgC[triple chemical bond]CtBu5 AgCF(3)CO(2)4 CH(3)CNH(2)O (2), a 2D hybrid coordination/hydrogen-bonded network in AgC[triple chemical bond]CtBu3 AgCF(3)CO(2)CH(3)CH(2)CN2 H(2)O (3), and another 2D coordination network in AgC[triple chemical bond]CtBu4 AgCF(3)CO(2) (CH(3))(3)CCN2 H(2)O (4). Concomitantly, the linkage modes between adjacent ethynide-bound Ag(n) aggregates in these compounds are also changed. A layer-type hydrogen-bonded host lattice in isostructural AgC[triple chemical bond]CtBu4 AgCF(3)CO(2)(R(4)N)(CF(3)CO(2)) 2 H(2)O (R(4)=BnMe(3), 5; R(4)=Et(4), 6; R(4)=nPr(4), 7) is obtained by introducing quaternary ammonium cations as guest templates, which occupy the interstices and thereby mediate the interlayer separation. Use of the bulky nBu(4)N(+) cation leads to disruption of the host network in AgC[triple bond]CtBu4 AgCF(3)CO(2)3[(nBu(4)N)(CF(3)CO(2))]H(2)O (8) with generation of a discrete dense nido-Ag(5) cluster.

Dipyrazinyl sulfoxide complexes of silver(I), zinc(II), and cadmium(II): ligation modes and anion tuning.

The new ligand dipyrazinyl sulfoxide (also named sulfinyldipyrazine and abbreviated as pyz(2)SO) and a series of its metal complexes including {[Ag(pyz(2)SO)](NO(3)).CH(3)CN}(infinity) (1), {[Ag(pyz(2)SO)](PF(6))}(infinity) (2), [Ag(3)(pyz(2)SO)(2)(ClO(4))(3)](infinity) (3), [Ag(pyz(2)SO)(CF(3)CO(2))](infinity) (4), {[Zn(pyz(2)SO)(H(2)O)(4)](NO(3))(2).H(2)O}(infinity) (5), {[Zn(pyz(2)SO)(H(2)O)(2)](ClO(4))(2)}(infinity) (6), and {[Cd(pyz(2)SO)(2)(H(2)O)](ClO(4))(2).H(2)O}(infinity) (7) have been synthesized and characterized by single-crystal X-ray analysis. The counteranions in these complexes prefer to be embraced by a pair of pi-acidic heterocyclic rings via anion-pi interactions, which consequently affect the process of supramolecular assembly. Seven distinct ligation modes of pyz(2)SO involving various bonding combinations of the sulfoxide oxygen and/or pyrazinyl nitrogen atoms (labeled A-G) are observed. Diverse coordination motifs such as (4,4) network, ladder-type, necklace-like, linear, and zigzag-chain structures are found in 1-7. Interestingly, the sulfoxide group of the pyz(2)SO ligand exhibits unusual dipolar sulfinyl...sulfinyl and S=O...pi(pyrazinyl) intermolecular interactions in the supramolecular assemblies of neat pyz(2)SO, 1, and 3-5.

Supramolecular frameworks constructed from angular-shaped sulfonyldipyrazine and various silver(I) salts

The new angular-shaped multidentate ligand sulfonyldipyrazine (abbreviated as L) is capable of forming diverse coordination polymeric motifs with various silver(I) salts, such as the infinite chain structure of [Ag3(L)(NO2)3]∞, (4,4) net of isomorphous {[Ag(L)](ClO4)}∞ and [Ag(L)(NO3)]∞, and three-dimensional frameworks of [Ag(L)(CF3SO3)]∞ and [Ag(L)(CF3CO2)]∞. In these complexes, sulfonyldipyrazine exhibits flexible ligation modes with its pyrazinyl N atoms bound to adjacent metal centers. The electron-deficient pyrazinyl rings and the sulfonyl group at the bend provide additional bonding sites for unconventional interactions, such as anion–π(pyrazinyl) and SO⋯π(pyrazinyl) interactions, in the supramolecular assembly of these complexes.