MONOMERIC GROUP-IIA METAL BETA-DIKETONATES STABILIZED BY MULTIDENDATE GLYMES

The reaction of the oligomeric alkaline earth metal beta-diketonate complexes, [M(beta-diket)2]infinity with a glyme ligand, yields the monomeric materials [M(beta-diketonate)2(L-L)]. The complexes [Ca(thd)2(triglyme)] (1), [Ca(hfa)2-(tetraglyme)] (2), and [Ba(thd)2(triglyme)] (3), have been characterized by IR and H-1 and C-13 NMR spectroscopy, mass spectrometry, and single-crystal X-ray studies. For [Ca(thd)2(triglyme)] (1) is triclinic, a = 10.378(3) angstrom, b = 11.601(4) angstrom, c = 15.483(3) angstrom, a = 84.03(3)-degrees, beta = 71.75(2)-degrees, gamma = 82.61(3)-degrees, and Z = 2; a monomeric eight-coordinate calcium complex is observed. The complex [Cu(hfa)2(tetraglyme)] (2) is triclinic, and is also eight coordinate, binding to only four of the five available oxygen atoms of the glyme ligand, leaving a dangling uncoordinated arm: a = 9.453(2) angstrom, b = 12.600(2) angstrom, c = 13.215(4) angstrom, alpha = 70.30(2)-degrees, beta = 83.09(2)-degrees, gamma = 76.49(2)-degrees, and Z = 2. The complex [Ba(thd)2(triglyme)] (3) is monoclinic, a = 10.688(2) angstrom, b = 23.614(6) angstrom, c = 15.650(3) angstrom, beta = 109.11-degrees, and Z = 4. The structure is similar to that of 1 in that it is also eight coordinate, binding to the two beta-diketonate ligands and the four oxygen atoms of the glyme ligand. The coordination geometry is markedly different, being bicapped trigonal antiprismatic compared with the square antiprismatic geometry observed for compounds 1 and 2.