THE NEUTRAL MULTILIGAND AND CATION COMPLEXES WITH BORON; C₁₁H₁₁O₄B, C₃₀H₂₂O₄BClO₄. I.Zviedre, J.Schwartz, V.Belsky, Institute of Inorganic Chemistry, Latvian Academy of Sciences, Latvia

In contrast to the anionic coordination compounds, a series of compounds exists derived from [[beta]]-diketones in which the boron atom forms cation or neutral complexes. We have determined two crystal structures which contain the central BO₄-tetrahedron.

I 2,4-Pentanedion-2,3-phendioxoborate C₆H₄O₂BO₂C₃H(CH₃)₂, II bis(1,3diphenyl-1,3-propanedion)boro(III)perchlorate ((C₆H₅)₂C₃HO₂)₂B^*ClO₄.

In complex I the boron atom is coordinated to one diol ligand and one [[beta]]-diketone ligand. The boron-oxygen tetrahedron is, due the unequal B-O bond lenghts, symmetrical distorted. Bond lenghts are B-O(alkyl) 1.445(4) and B-O(keto) 1.495(4) Å; C-O(alkyl) 1.370(3) and C-O(keto) 1.296(4) Å. Bond angles on B are from 107.6(2)deg. to 110.7(3)deg..

In the structure II the four O atoms adopt an almost perfect tetrahedral arrangement about the boron with bond lenghts B-O mean 1.46(I) Å, bond angles O-B-O are between 107.7(2)deg. and 112.5(3)deg.. Bond lenghts C-O are 1.31 (2) Å. All heterocycles in both compounds are non-planar.

Crystal data: I - a=10.059(2), b=12.617(2), c=8.502(10) Å, [[gamma]]=95.44(2) deg., Z=4, sp.gr. P2_l/n, II - a=22.724(4), b=13.740(3), c=8.763(2) Å, [[gamma]]=99.06(1) deg., Z=4, sp.gr. P2_l/a [1].

Our thanks are due to O.Korotkich from the University of Vladivostok for the supply the compounds I, II for recrystallization.

[1] Zviedre I., Belsky V. /Thes.VII Conf.SSSR, Khim.Dicarb.S., 1991, 93.