Structures of hybrid inorganic–organic salts with benzidine dication derivatives

Abstract

We describe and analyse seven new structures containing various metal-halide complex anions and differently substituted benzidine cations. We also introduce a series of criteria defining global architecture of such type of structures. All the structures analysed are of the layered type. However, only two of them contain infinite sheets of polymerised inorganic anions. We also calculate some other parameters defining the geometry and orientation of cations in the structures such as linear and area densities of charge, distance between ionic layers or interstack distance. Our analysis is also based on the other structures containing benzidine dication or its derivatives. An expected decrease of cationic charge generated in layers of inorganic–organic hybrid salts with benzidine derivatives is associated not only with the steric hindrance working as a buffer. It appears that the tilt angle of the cations with respect to the defined ionic layers is an even more important factor. This loss of packing of cations allows the formation of polymerised inorganic sheets of relatively big Pb(II) chlorides. This process does not take place in the case of the smaller Cu(II) chloride. On the other hand, the substitution has no influence on grouping cations into stacks in the structures when a specific orientation of cations is present. Thus, the cation–cation distance stays substitution independent and in some cases becomes smaller than for the unsubstituted benzidine moiety. The aggregation of twisted cations in each stack prevents steric repulsion of the substituents.