Reactions of 3,5-Pyrazoledicarboxylic Acid with Organotin Chlorides and Oxides. Coordination Polymers Containing Organotin Macrocycles

The reaction of 3,5-pyrazoledicarboxylic acid (LH3) with di- and triorganotin substrates has been investigated. The reaction of LH3 with (PhCH2)2SnCl2 afforded a macrocycle-containing coordination polymer [{((PhCH2)2Sn)6(μ-L)4(μ-OH)2}{((PhCH2)2SnCl)2}]n (1), which upon reaction treatment with pyridine (py) in the presence of water yielded a coordination polymer [{((PhCH2)2Sn)6(μ-L)4(μ-OH)2(py)2}{((PhCH2)2Sn)2(μ-O)(μ-OH)}2]n (2). Treatment of 1 with 2,4,6-collidine in the presence of water afforded [{(PhCH2Sn)12(μ-O)14(μ-OH)6}{((PhCH2)2Sn)6(μ-L)4(μ-OH)2}]·2C4H8O·2C2H5OH·2H2O (3). The latter contains a dodecanuclear oxotin cage as a dication and a hexanuclear tin macrocycle as the dianion. O−H ··· O hydrogen-bonding interaction between the cation and the anion leads to the formation of a supramolecular 2D polymer containing large macrocyclic voids. In a slight variation, if the reaction of LH3 is carried out with Me2SnCl2 in the presence of KOH, a heterobimetallic compound [{(K)2(H2O)2(μ-H2O)3(EtOH)2}{((CH3)2Sn)4(μ-L)3(μ-OH)}]n·2H2O (4) is formed. An interesting aspect of the structure of 4 is that the two potassium atoms present in this compound are bridged to each other by three water molecules. 4 is a 2D-coordination polymer, which is taken into a 3D supramolecular structure by solvent ethanol molecules. The reactions of LH3 with Ph2SnO lead to the formation of an insoluble product 5a, which could be dissolved in hot N,N′-dimethylformamide to afford [{(CH3)2NH2}2{(Ph2Sn)(μ-L)(H2O)}2] (5). An analogue of 5, [{(CH3)2NH2}2{(Ph2Sn)(μ-L)(CH3OH)}2] (6), was also prepared more directly by crystallization of 5a in the presence of dimethylamine or bis(dimethylamino)methane. Both 5 and 6 are dinuclear, and their structural integrity is retained in solution as shown by ESI-MS studies. The reaction of (nBu3Sn)2O with LH3 leads to an unusual Sn−alkyl bond cleavage affording a 2D-coordination polymer [(nBu2Sn)2(μ-L)2(nBu3Sn)2]n (8) where dinuclear tin macrocycles are linked to each other by nBu3Sn bridges. In contrast, the reaction of (Ph3Sn)2O with LH3 affords a dinuclear compound [(Ph3Sn)2(μ-LH)(H2O)]·(H2O)2 (9) where the two tin atoms are coordinated by only the carboxylate oxygen atoms. However, the interaction of the coordinated water molecule along with lattice water leads to the formation of a chair-shaped (H2O)6 cluster, which acts as a bridge between two successive molecules.