Syntheses and Structures of Acetyl-Acetonato-Alumo-Diphenylsilanolates with Magnesium(II), Iron(II), Iron(III), Cobalt(II), and Nickel(II)

Bis(acetylacetonate)alumo-oxo-tetraphenyldisiloxane-metal(II) dihydrates [(acac)(2)Al(O-SiPh2-O-SiPh2-O)](2)M(H2O)(2) (M = Mg, Fe, Co, Ni) were obtained from the corresponding acetyl-acetonate- dihydrates (acac)(2)M(H2O)(2) by reaction with the alumosiloxane [O-Ph2Si-O-SiPh2-O](4)Al-4(OH)(4). These new compounds display two acac ligands at the aluminum atoms as well as disilatrioxy chains linking the two aluminum atoms forming a (Al-O-Si-O-Si-O)(2) cycle (Xray structure analyses). Within this cycle the divalent metal ions M2+, to which two water molecules in trans positions are linked, are installed in almost planar MO4 coordination spheres. Using water free (acac)(2)Ni a different product forms: both reactants combine in a 2: 1 ratio to yield [O-Ph2Si-O-SiPh2-O](4)Al-4(OH)(2)O(OH2)Ni-2(acac)(4). Here, three of the acac ligands were transposed to the aluminum atoms. The nickel atoms are in a distorted octahedral coordination mode from oxygen atoms of the ligands. When iron(III) tris(acetylacetonate) reacts with the alumosiloxane [O-Ph2Si-O-SiPh2-O](3)Al2O(OH)Fe-2(acac)(3) was isolated, in which the two iron atoms still display one of the acac ligands. One of the aluminum atoms is in a tetrahedral oxygen environment, whereas the other is in the center of a trigonal bi-pyramid formed of oxygen atoms either of the siloxane or of acac. The iron atoms have five-or sixfold coordination from oxygen atoms of siloxane, acac, hydroxide or oxide.