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

Abstract

The reaction of 3,5-pyrazoledicarboxylic acid (LH 3 ) with di- and triorganotin substrates has been investigated. The reaction of LH 3 with (PhCH 2 ) 2 SnCl 2 afforded a macrocycle-containing coordination polymer [{((PhCH 2 ) 2 Sn) 6 (μ-L) 4 (μ-OH) 2 }{((PhCH 2 ) 2 SnCl) 2 }] n ( 1 ), which upon reaction treatment with pyridine (py) in the presence of water yielded a coordination polymer [{((PhCH 2 ) 2 Sn) 6 (μ-L) 4 (μ-OH) 2 (py) 2 }{((PhCH 2 ) 2 Sn) 2 (μ-O)(μ-OH)} 2 ] n ( 2 ). Treatment of 1 with 2,4,6-collidine in the presence of water afforded [{(PhCH 2 Sn) 12 (μ-O) 14 (μ-OH) 6 }{((PhCH 2 ) 2 Sn) 6 (μ-L) 4 (μ-OH) 2 }] · 2C 4 H 8 O · 2C 2 H 5 OH · 2H 2 O ( 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 LH 3 is carried out with Me 2 SnCl 2 in the presence of KOH, a heterobimetallic compound [{(K) 2 (H 2 O) 2 (μ-H 2 O) 3 (EtOH) 2 }{((CH 3 ) 2 Sn) 4 (μ-L) 3 (μ-OH)}] n ·2H 2 O ( 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 LH 3 with Ph 2 SnO lead to the formation of an insoluble product 5a, which could be dissolved in hot N, N ′-dimethylformamide to afford [{(CH 3 ) 2 NH 2 } 2 {(Ph 2 Sn)(μ-L)(H 2 O)} 2 ] ( 5 ). An analogue of 5, [{(CH 3 ) 2 NH 2 } 2 {(Ph 2 Sn)(μ-L)(CH 3 OH)} 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 ( n Bu 3 Sn) 2 O with LH 3 leads to an unusual Sn−alkyl bond cleavage affording a 2D-coordination polymer [( n Bu 2 Sn) 2 (μ-L) 2 ( n Bu 3 Sn) 2 ] n ( 8 ) where dinuclear tin macrocycles are linked to each other by n Bu 3 Sn bridges. In contrast, the reaction of (Ph 3 Sn) 2 O with LH 3 affords a dinuclear compound [(Ph 3 Sn) 2 (μ-LH)(H 2 O)]·(H 2 O) 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 (H 2 O) 6 cluster, which acts as a bridge between two successive molecules.