Pyridinedicarboxylic Acids as Versatile Building Blocks for Coordination-Driven Self-Assembly: Solvent-Induced Macrocycle and Coordination Polymer Formation upon Combination of 2,5-Pyridinedicarboxylate with Diorganotin Moieties

摘要

Ligands derived from 2,x- and 3,y-pyridinedicarboxylic acid (x = 3-6; y = 4-5) are widely used building blocks for the formation of metal-coordination polymers (MCPs), as they show a large variety of bridging modes and angles. Metal complexation occurs either only with the carboxylate groups or through N,O-chelate ring formation. In this contribution, the supramolecular chemistry and solvatomorphism of diorganotin complexes with 2,5-pyridinedicarboxylate (25pdc) formed in the presence of a series of coordinating and noncoordinating solvents were explored in detail. Five novel diorganotin 25pdc's of composition [Me2Sn(25pdc)(py)](3)center dot 3.04C(5)H(5)N center dot 1.86H(2)O (1), {[Me2Sn(25pdc)]center dot[Me2Sn(25pdc)(H2O)]}(n) 2nC(7)H(8)O (2), {[nBu(2)Sn(25pdc)](4)})(n)center dot 4nC(6)H(5)NO(2) (3), [nBu(2)Sn(25pdc)(gly)](n) (4), and {[nBu(2)Sn center dot(25pdc)](3)}(n)center dot nCHCl(3) (5) were achieved and analyzed in the context of previously reported tri- and diorganotin complexes with the same ligand. The comparative study revealed that upon coordination to diorganotin species the ligand exhibits N,O-chelate ring formation with the carboxylate group in the 2-position and bridging to other tin atoms primarily by the 5-carboxylate group, giving macrocyclic, one-, two-, or three-dimensional MCPs. On the contrary, triorganotin moieties are mostly bound only by the ligand carboxylate groups without N - Sn binding. The assemblies of diorganotin 25pdc's mostly contain trinuclear or tetranuclear macrocycles with a large predominance of the generally uncommon [3 + 3] metal-organic aggregates. For the trinuclear macrocycles, different configurations having 12-, 18-, 21-, or 27-membered rings were encountered. The metal atoms in diorganotin 25pdc's prefer pentagonal-bipyramidal environments, which are achieved through coordination by solvent molecules (H2O, DMSO, py) or intermolecular O - Sn bond formation. In solution, di-n-butyltin 25pdc exhibits supramolecular isomerism, giving a tetrameric aggregate in the noncoordinating solvent chloroform and a trimeric species in the presence of coordinating solvents, such as DMSO, pyridine, or methanol, due to solvent - Sn bond formation.