SYNTHESES AND CRYSTAL-STRUCTURES OF DIAZA DIENE COMPLEXES OF THE ALKALINE-EARTH METALS

[CaNR-CPh=CPh-NR(DME)(2)] 1 (R = C6H4-4-CH3; DME = dimethoxyethane) wa s prepared by reaction of calcium with NR=CPh-CPh=NR in DME solution. The compound forms orange, moisture sensitive crystals, which were cha racterized by an X-ray structure determination [space group orthorhomb ic, P2(1)2(1)2(1), Z = 4, 4634 observed unique reflectional R = 0.046, lattice dimensions at -70 degrees C: a = 1340.2(3), b = 1528.1(3), c = 1609.1(3) pm]. The calcium atom is coordinated by the four oxygen at oms of two chelating DME molecules and two nitrogen atoms of the diaza diene ligand, bonded in its enediamide form. [Ba-2(DME)(3)(NPh-CPh=CPh -NPh)(2).DME] 3 was obtained from barium metal and NPh=CPh-CPh=NPh in DME solution as red crystals [space group monoclinic, P2(1)/c, Z = 4, 4000 observed unique reflections, R = 0.166; lattice dimensions at -70 degrees C: a = 1704.5(3), b = 1786.1(4), c = 2177.4(4) pm, beta = 105 .98(3)degrees]. The two barium atoms are bridged by two differently bo nded diazadiene ligands (mu(2)-N,N'; mu-N, sigma-N'). Additionally, on e of the barium atoms is coordinated to two DME molecules and the othe r one to only one of the ether molecules. A further DME molecule is a constituent of the crystal lattice.