Interaction of aromatic hydrocarbons with organometallic compounds of the main group elements: VI. Synthesis and crystal structure of cesium diiododimethylaluminatep-xylene solvate,Cs[Al(CH3)2I2]·C6H4(CH3)2

The crystal structure of thep-xylene solvate of cesium diiododimethylaluminate has been determined from counter data, and refined by full-matrix least-squares techniques. The crystals belong to the orthorhombic space groupC222₁ witha = 12.577(4),b = 9.311(3),c = 14.256(4) Å, andD _x = 2.19 g cm^–3 forZ = 4. The finalR value for 481 observed reflections is 0.036. The anion resides on a two-fold axis; the Al-I bond length is 2.647(4) Å, and the Al-C distance, 1.98(2) Å. Important bond angles include I-Al-I, 102.3(2) °; C-Al-C, 115(1) °; I-Al-C, 114(3) °; and I-Al-C, 106(3) °. The cesium ion also lies on the two-fold axis. Throughout the crystal the cesium ions are separated byp-xylene molecules. The Cs C distances average 3.84 Å. In the lattice the iodine atoms reside on thea,b face diagonals (and symmetry-related positions) and are situated almost exactly between the cesium ions. The Cs I contact, 3.925(1) Å, is consistent with a significant bonding interaction.For Part V see Atwood et al. (1978).