Regioisomer-Dependent Endo- and Exocyclic Coordination of Bis-Dithiamacrocycles

Influence of the Reaction Sequence on the Complexation of an NS4-Macrocycle with CdII and CuI Salts Leading to the Formation of Supramolecular Isomers and an Endo/Exocyclic CuI Complex

In the construction of metallosupramolecules, the reaction sequence in a three-reactant system (one ligand plus two metal ions) could be one of the controlling factors influencing the outcome of the reaction. In this work, the formation of supramolecular isomers (1 and 2) and an endo/exocyclic Cu⁺ complex (4) of the NS₄-macrocycle (L) via different sequential metal addition protocols (routes I-III) is reported. In one-pot reactions of L with Cu(CH₃CN)₄PF₆ in the absence (route I) and presence (route II) of CdI₂, a cyclic dimer Cu^I complex, [Cu₂(L)₂](PF₆)₂ (1), and a one-dimensional coordination polymer, [Cu₂(L)₂]_n·n[CdI₄] (2), were obtained, respectively. Interestingly, the complex cations in 1 and 2 are supramolecular isomers formed via cyclization and polymerization upon complexation, respectively, probably due to different geometric and electronic complementarities, via the C-H···X^- hydrogen bonds, between L and the counterion. In the two-step reaction (route III), an endocyclic Cd²⁺ complex, [Cd(L)I₂] (3), obtained in the first step was utilized in the following reaction with Cu(CH₃CN)₄PF₆, giving rise to an endo/exocyclic tetranuclear Cu⁺ complex, [Cu₄(L)₂(CH₃CN)₆](PF₆)₄ (4), via Cd²⁺ → 2Cu⁺ substitution, which is not accessible by conventional procedures. Solution studies by comparative NMR and electrospray ionization mass spectroscopy also support metal substitution by showing the stronger binding affinity of Cu⁺ over Cd²⁺. These results demonstrate that the metal substitution protocol could be useful for reaching novel metallosupramolecules difficult to obtain by other methods.

The crystal structures, Hirshfeld surface analyses and energy frameworks of two hexa-thia-pyrazino-phane regioisomers; 2,5,8,11,14,17-hexa-thia-[9.9](2,6,3,5)-pyrazino-phane and 2,5,8,11,14,17-hexa-thia-[9.9](2,5,3,6)-pyrazino-phane

The title thia-pyrazino-phanes, 2,5,8,11,14,17-hexa-thia-[9.9](2,6,3,5)-pyrazino-phane, C16H24N2S6, (I), and 2,5,8,11,14,17-hexa-thia-[9.9](2,5,3,6)-pyrazino-phane, C16H24N2S6, (II), are regioisomers; m-bis L1 and p-bis L1, respectively. Both compounds have a central tetra-2,3,5,6-methyl-ene-pyrazine unit with two -S-CH2-CH2-S-CH2-CH2-S- chains, linking the methyl-ene C atoms at positions 2 and 6 and 3 and 5 on the pyrazine ring of I, but linking the methyl-ene C atoms at positions 2 and 5 and 3 and 6 on the pyrazine ring of II. Both compounds crystallize with half a mol-ecule in the asymmetric unit. The whole mol-ecule of I is generated by inversion symmetry, with the pyrazine ring being located about a center of symmetry. The whole mol-ecule of II is generated by twofold rotation symmetry, with the pyrazine N atoms being located on the twofold rotation axis. In compound I, there are pairs of intra-molecular C-H⋯S contacts present, but none in compound II. In the crystal of I, there are no significant inter-molecular inter-actions present, while in the crystal of II, mol-ecules are linked by pairs of C-H⋯S hydrogen bonds, forming corrugated layers lying parallel the ac plane. The Hirshfeld surfaces and the energy frameworks of the two regioisomers indicate little difference in the inter-atomic contacts, which are dominated by dispersion forces.

Silver(I) nitrate two-dimensional coordination polymers of two new pyrazine-thio-phane ligands: 5,7-di-hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine and 3,4,8,10,11,13-hexa-hydro-1H,6H-bis-([1,4]di-thio-cino)[6,7-b:6',7'-e]pyrazine

The two new pyrazine-ophanes, 5,7-di-hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine, C8H8N2S2, L1, and 3,4,8,10,11,13-hexa-hydro-1H,6H-bis-([1,4]di-thio-cino)[6,7-b:6',7'-e]pyrazine, C12H16N2S4, L2, both crystallize with half a mol-ecule in the asymmetric unit; the whole mol-ecules are generated by inversion symmetry. The mol-ecule of L1, which is planar (r.m.s. deviation = 0.008 Å), consists of two sulfur atoms linked by a rigid tetra-2,3,5,6-methyl-ene-pyrazine unit, forming planar five-membered rings. The mol-ecule of L2 is step-shaped and consists of two S-CH2-CH2-S chains linked by the central rigid tetra-2,3,5,6-methyl-ene-pyrazine unit, forming eight-membered rings that have twist-boat-chair con-fig-urations. In the crystals of both compounds, there are no significant inter-molecular inter-actions present. The reaction of L1 with silver nitrate leads to the formation of a two-dimensional coordination polymer, poly[(μ-5,7-di-hydro-1H,3H-dithieno[3,4-b;3',4'-e]pyrazine-κ2 S:S')(μ-nitrato-κ2 O:O')silver(I)], [Ag(NO3)(C8H8N2S2)] n , (I), with the nitrato anion bridging two equivalent silver atoms. The central pyrazine ring is situated about an inversion center and the silver atom lies on a twofold rotation axis that bis-ects the nitrato anion. The silver atom has a fourfold AgO2S2 coordination sphere with a distorted shape. The reaction of L2 with silver nitrate also leads to the formation of a two-dimensional coordination polymer, poly[[μ33,4,8,10,11,13-hexa-hydro-1H,6H-bis-([1,4]di-thio-cino)[6,7-b;6',7'-e]pyrazine-κ3 S:S':S''](nitrato-κO)silver(I)], [Ag(NO3)(C12H16N2S4)] n , (II), with the nitrate anion coordinating in a monodentate manner to the silver atom. The silver atom has a fourfold AgOS3 coordination sphere with a distorted shape. In the crystals of both complexes, the networks are linked by C-H⋯O hydrogen bonds, forming supra-molecular frameworks. There are additional C-H⋯S contacts present in the supra-molecular framework of II.

Alkali metal complexes of bis-o-xylyl-(17-crown-5): from a dinuclear monomer and a dinuclear polymer to sandwich polymer

The self-assembly reactions of bis-o-xylyl-(17-crown-5) with alkali metal salts afforded binding mode (good fit, perching and sandwich)-dependent supramolecular complexes, including a sandwich-type cesium(i) coordination polymer.

Influence of mole-ratio on the coordination behaviour of a ditopic N2O2S2-macrocycle: endo/exocyclic silver(i) coordination polymer exhibiting desolvation-induced SCSC transformation

Mole-ratio dependent macrocyclic silver(i) complexes including an endo/exocyclic 1-D coordination polymer exhibiting desolvation-induced SCSC transformation are reported.

Endocyclic and Endo–Exocyclic Silver(I) Complexes of Thiaoxaaza Macrocycles: Crystallographic and NMR Studies

A comparative investigation of the coordination behaviour of a 19-membered NO2S2-macrocycle (L1) and a 20-membered NO2S3-macrocycle (L2) is reported. On silver(i) complexation, L1 yields a discrete endocyclic mononuclear complex, whereas L2 affords a one-dimensional coordination polymer in which the endo-coordinated macrocyclic complex units are linked by silver(i) ions outside the cavity via endo–exo-coordination. The larger ring cavity along with the flexible nature of L2 may induce the weaker endocyclic complexation and contribute to exocyclic coordination as well. In NMR titration studies for the corresponding complex system, however, no evidence of exocyclic coordination was observed. Instead, L1 and L2 form a stable endocyclic 1 : 1 silver(i) nitrate complex, with a higher affinity for the former ligand.

Syntheses and structures of one CuI-containing coordination polymer and two macrocyclic supramolecular complexes based on flexible 1,3,4-oxadiazole-containing ligands

Three coordination complexes with Cu(I) centres have been prepared using the symmetrical flexible organic ligands 1,3-bis{[5-(quinolin-2-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}propane (L1) and 1,4-bis{[5-(quinolin-2-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}butane (L2). Crystallization of L1 with Cu(SO3CF3)2 and of L2 with Cu(BF4)2 and Cu(ClO4)2 in a CH2Cl2/CH3OH mixed-solvent system at room temperature afforded the coordination complexes catena-poly[[copper(I)-μ-1,3-bis{[5-(quinolin-2-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}propane] methanesulfonate dichloromethane 0.6-solvate], {[Cu(C25H18N6O2S2)](CF3SO3)·0.6CH2Cl2}n, (I), bis(μ-1,4-bis{[5-(quinolin-2-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}butane)dicopper(I) bis(tetrafluoridoborate)-dichloromethane-methanol (1/1.5/1), [Cu2(C26H20N6O2S2)2](BF4)2·1.5CH2Cl2·CH3OH, (II), and bis(μ-1,4-bis{[5-(quinolin-2-yl)-1,3,4-oxadiazol-2-yl]sulfanyl}butane)dicopper(I) bis(perchlorate)-dichloromethane-methanol (1/2/1), [Cu2(C26H20N6O2S2)2](ClO4)2·2CH2Cl2·CH3OH, (III). Under the control of the dumbbell-shaped CF3SO3(-) anion, complex (I) forms a one-dimensional chain and neighbouring chains form a spiral double chain. Under the control of the regular tetrahedron-shaped BF4(-) and ClO4(-) anions, complexes (II) and (III) have been obtained as bimetallic rings, which further interact via π-π interactions to form two-dimensional networks. The anions play a decisive role in determining the arrangement of these discrete molecular complexes in the solid state.