Self-assembly of square planar rhodium carbonyl complexes with 4,4-disubstituted-2,2 '-bipyridine ligands

摘要

The impact of non-covalent interactions and reaction conditions on formation and self-assembly of ionic pairs of Rh complexes with 4,4'-disubstituted bipyridine ligands ([Rh(L1)(CO)(2)][Rh(CO)(2)Cl-2])(n) (1), [Rh(L1)(2)Cl-2][Rh(CO)(2)Cl-2] (2), ([Rh(L1)(CO)(2)][Rh(CO)(2)Cl-2] [Rh(L1(CO)(2)](n) ([Rh(CO)(2)Cl)(2)](n)) (3), ([Rh(L2)CO2] [Rh(CO)(2)Cl-2])(n)center dot EtOH (4), ([Rh(L2)(CO)(2)])(n) ([Rh(CO)(2)Cl-2]) (5) (L1 = 4, 4'-dimethyl-2,2'-bipyridine, L2 = 4,4'-diamine-2,2'-bipyridine) have been studied. Packing of square planar Rh complexes favor formation of onedimensional chains. In structure 1, the polymeric chain is formed by the alternating cationic [Rh(L1)(CO2](+) and the anionic [Rh(CO)(2)Cl-2](-) units leading to a neutral pseudo linear 1D chain with metallophilic contacts. In compound 2, the square planar [Rh(CO)(2)Cl-2](-) anions form only dinuclear anion pairs instead of polymeric chains. Structure 3 consists of an alternative arrangement of cations and anions compared to 1, the repeating sequence of ions being [Rh(L1)(CO)(2)](+) [Rh(CO)(2)Cl-2] [Rh(L1)(CO)(2)](+). The overall positive charge is balanced by outlying [Rh(CO)(2)Cl-2](-) counterion. In structures 4 and 5, only the cationic [Rh(L2)(CO)(2)](+) units are involved in formation of the polymeric chains and the positive charge of the chain is balanced by the [Rh(CO)(2)Cl-2](-) (4 and 5). In structures 1 and 3 the metallophilic interactions have an important role in chain formation. In 4 and 5, the arrangement of the square planar building blocks is dominated by the hydrogen bonding between the NH2-substituents of the bipyridine ligand and the chlorides of the anion or solvent of crystallization.