SYNTHESIS AND CHARACTERIZATION OF THE FIRST GROUP 2 MIXED BETA-DIKETONATE ALKOXIDE COMPLEXES - X-RAY CRYSTAL-STRUCTURES OF [CA-4(TMHD)(4)(OET)(4)(ETOH)(4)],[CA-4(TMHD)(6)(OCH2 CH(2)NME(2))(2)], AND [H2BA4(TMHD)(6)(OCH2CH2OPRI)(4)]

The reaction of the ethanol-solvated metal ethoxides [M(OEt)(2)(EtOH)(4)](infinity) (M = Ca, Sr, Ba) in n-hexane suspensions/solutions with 1 equiv of a beta-diketone, H-tmhd {H-tmhd is Bu(t)COCH(2)COBu(t)}, yields the compounds [Ca-4-(tmhd)(4)(OEt)(4)(EtoH)(4)] (1), [Sr(tmhd)(OEt)(EtOH)(0.66)](n) (2), and [Ba(tmhd)(1.5)(OEt)(0.5)(EtOH)(0.33)](n), (3); further reaction of these complexes with a bifunctional alcohol yields the complexes [Ca-4(tmhd)(6)(OCH(2)CH(2)NMe(2))(2)] (4), [Ca(tmhd)(1.5)(OCH2CH2OPri)(0.5)](n) (5), [Sr(tmhd)(OCH(2)CH(2)NMe(2))](n) (6), [H0.5Sr(tmhd)(1.5)(OCH(2)CH(2)OMe)](n) (7), [H-2- Ba-4(tmhd)(6)(OCH2CH2OPri)(4)] (8), and [H0.5Ba(tmhd)(1.5)(OCH(2)CH(2)OMe)](n), (9) {the values of n are as yet unknown}. 1, 4, and 8 have also been characterized by X-ray crystallography. Crystal data: for 1, monoclinic space group P2(1)/c, a = 14.781(2) Angstrom, b = 26.959(7) Angstrom, c = 20.443(2) Angstrom, beta = 110.60(2)degrees, Z = 4; for 4, monoclinic space group P2(1)/n, a = 14.1803(7) Angstrom, b = 12.047(3) Angstrom, c = 25.114(5) Angstrom, beta = 100.64(1)degrees, Z = 2; for 8, monoclinic space group C2/c, a = 30.899(7) Angstrom, b = 11.395(2) Angstrom, c = 29.782(5) Angstrom, beta = 103.08(1)degrees, Z = 4. Complexes 1, 4, and 8 are all tetrameric with a M(4)O(4) structural motif; 1 has a cubane type structure while 4 and 8 are built from a ladder-like framework. All Ca atoms in 1 have very similar six-coordinate octahedral symmetry. The two unique Ca atoms in 4, which is centrosymmetric, are also six-coordinate, but one is octahedral and the other is trigonal prismatic. In complex 8, which is also centrosymmetric, the environments of the two unique Ba atoms are again different, one showing an eight-coordinate, bicapped trigonal prismatic and the other a nine-coordinate, monocapped square prismatic geometry. Compounds 1-9 may have properties pertinent for application as sol-gel precursors.