FORMATION OF AZACROWN COMPLEXES OF TIN(IV) - CRYSTAL AND MOLECULAR-STRUCTURE OF [H2L]2[SNCL5(H2O)]2.H2O.MECN (HL = 1,4,7,10,13-PENTAOXA-16-AZACYCLOOCTADECANE)

Reaction of SnCl4 and aza-18-crown-6 (1,4,7,10,13-pentaoxa-16-azacyclo octadecane, HL) provides the white solid SnCl3L 1 with elimination of HCI. Analytical and spectroscopic characterisation of 1 points to a st ructure in which a SnCl3 unit is bonded to the deprotonated nitrogen a tom and the two adjacent oxygen atoms of the azacrown. Partial hydroly sis of 1 during an attempted recrystallisation in acetonitrile, gave c olourless crystals of the ionic compound [H2L]2[SnCl5(H2O)]2.H2O.MeCN 2 the structure of which was determined by X-ray diffraction: monoclin ic, space group C2/m, a = 40.15(2), b = 12.231 (6), c = 10.019(7) angs trom, beta = 104.05(5)-degrees, Z = 4. Two independent azacrown molecu les are both protonated. Molecule 1 has the solvate water molecule loc ated centrally over the ring cavity, held by three strong O-H(water) . .. O(ring) 2.793 and O(water) ... H-N(ring) 2.690 angstrom hydrogen bo nds; molecule 2 behaves as a second-sphere ligand to two separate six- co-ordinate (SnCl5(H2O)]- anions positioned on opposite sides of the r ing. The co-ordinated H2O molecules are located over the centre of the azacrown ligand and are involved in hydrogen bonding to the nitrogen and oxygen atoms of the ring.