Fourteen inorganic tin(iv) and organotin(iv) complexes of crown ethers (L), of general formulae SnX;L' 2H20, SnC14'L'4H20'nCHCI, (n = 0 or l ) , (SnR2X2),'L'2H20 (n = 1 or 2), and ( SnPh3X)2'L'2H20, have been synthesised. The structure and bonding in these adducts are discussed in terms of their i.r. and "9Sn Mossbauer spectroscopic data. These suggest co-ordination to the tin either by one or more of the polyether 0 atoms, or by the water molecules of hydration (the crown ether acting as a second-sphere ligand). The latter structure is confirmed by a single-crystal X-ray determination of Sn(OH2)2C14'1 8-~rown-6'2H~O*CHC1~. The crystals are monoclinic, space group P2,/n, with a = 10.315( 6), b = 13.630( 8), c = 20.649(13) A, and p = 94.68( 5)". The structure was solved using multisolution direct methods and refined by least squares to R = 0.062 (R' = 0.068) for 3 142 observed diffractometer data. The water molecules within the octahedral Sn(OH2)2C14 units are found to be cis to each other and are involved in an extensive hydrogen-bonding scheme. The latter links together the 18-crown-6 molecules, unco-ordinated water molecules, and Sn(OH2)2C14 octahedra, to give hydrogen-bonded chains which run parallel to the b axis.Recent studies on adducts of transition-metal aqua and ammine complexes with crown ethers have shown that the macrocyclic polyether is not directly co-ordinated to the metal atom, but acts as a second-sphere ligand, in which it interacts with either the co-ordinated water or ammonia molecules via hydrogen bonds.There are very few reports on the interaction of tin compounds with crown ethers. Herber and his co-workers have suggested, on the basis of i.r. and Mossbauer spectroscopy, that various inorganic tin(ii) salts furnish ionic complexes with 18-crown-6 and 15-~rown-5,~*: in which the Sn2+ cation interacts strongly with two (or three) of the polyether oxygen atoms. The only work on inorganic tin(1v) complexes of crown ethers is by Gur'yanova et a/.4 who reported the existence of the neutral adduct 2SnCI4*dibenzo-24-crown-8 in benzene solution. This adduct was not isolated in the solid state, but it was suggested that the crown ether functions as a quadridentate donor ligand, with each tin co-ordinated exocyclically to two oxygen atoms from the polyether ring.We now report on a extension of our preliminary studies on inorganic tin(lv) and organotin(iv) complexes of crown ethers, including the first crystal structure determination of a representative of the former type. 0
