Intermolecular interactions silver

T-7T Stacking or jt-jt interactions are important noncovalent intermolecular interactions, which contribute much to self-assembly when extended structures are formed from building blocks with aromatic moieties. In relation to the rich variety of jt-jt stacking in the crystal structure of silver complexes of phenylenediethynide, related silver complexes of phenylethynide and its homologues with different substituents (-CH3, -QC or the -CH3 group in different positions (0m-, p-) are investigated. 

So what about the cubic phase In polycatenar systems, it is possible to rationalize the formation of cubic phases on the basis of surface curvature alone, which will be considered in subsequent sections. However, it can be argued that, for calamitic systems, these arguments do not hold—at least on their own—and that other factors are important. For example, if cubic-phase formation is due to surface curvature, it is not possible to explain why an Sa phase (lamellar and with no surface curvature) is seen at higher temperatures. An important factor is the presence of specific intermolecular interactions and in the case of the silver systems, these are the intermolecular electrostatic interactions resulting from the presence of formally ionic groups. This is consistent with the observation of cubic phases in the biphenylcarboxylic acids and hydrazines (Fig. 29), as well as with other materials. However, it is also evident that this is not the only factor, as no cubic phase is seen with anion chains shorter than DOS, while other studies with fluorinated alkoxystilbazoles showed that the position of fluorine substitution could determine the presence or absence of the mesophase observed in the unsubstituted derivatives (56). Thus, structural factors are clearly not negligible. 

Mohamed, A.A., Perez, L.M. and Fackler, J.P. Jr (2005) Unsupported intermolecular argentophihc interaction in the dimer of trinuclear silver(I)... 

With the long alkyl chain substitutions on the A-heterocyclic carbenes, lamella-structured silver(i) carbene complexes 27a and 27b (Figure 14) were isolated.74 It is interesting to note that the synthetic procedures for the two complexes are the same except for the use of different solvents of crystallization. The dinuclear 27a was obtained from recrystallization in dichloromethane- -hexane while the tetranuclear 27b was obtained from acetone. The structure of 27a could be interpreted as the dimeric form of [Ag(carbene)Br] bridged by intermolecular Ag-Br interactions. The Ag-G bond has a distance of 2.094(5) A. The tetranuclear 27b, on the other hand, could be regarded as two monocationic bis(carbene)silver(i) bridged by an [Ag2Br4]2 anion, with the presence of short Ag(cationic)-Ag(anionic) contact (3.0038(18) A) and comparable Ag-G bond distances (2.0945(5), 2.138(13) A). A related... 

Crown ether 4 has been shown to be a source of unusual dinuclear silver(l) complexes <2002ICA(332)18>. In the crystal, the silver ions interact with the crown ether ligand at both the hard donor ethereal oxygens and soft benzene ring carbon atoms via intermolecular cation-Tt-interaction in -fashion, as depicted in Figure 6. The dimeric structure is further stabilized by the occurrence of intermolecular Tt-Tt-intcractions between facing benzo groups. 

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