Substituted trispyrazolylborates

Compounds 32a-c are insoluble in non-polar solvents and in the solid state the Ln(II) centers of 32a and 32c are bound by six N-donors and exhibit trigonal antiprismatic geometries and symmetry elements [73,74], Reactivity studies of 32a have been extensive and include the reduction of unsaturated organic substrates and of d-transition metal carbonyl complexes [72], The facile oxidation of 32a is highlighted by its reaction with 

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The substitution of the trans halide ligand and two equatorial ligands by tris-chelate ligands is a commonly employed synthetic reaction. Cyclopen-tadienyl derivatives were made according to Eq. (S3) (35,II 1,120.121) and Eq. (84) (69,88). Quite a variety of trispyrazolylborate derivatives were... 

I should like to thank the National Research Council of Canada for financial support of this research and S. Trofimenko of the Central Research Department, E. I. Du Pont de Nemours Co., for gifts of Co(II)-trispyrazolylborate and Co(II)trispyrazolylmethane. The results with substituted anilines were obtained in collaboration with H. O. Ohordnyk and Linda Seville. 

Catalyst TpRuPPh3(MeCN)2PFg (Tp is trispyrazolylborate) is much more active for benzannulation, and a concentration of 3 mol% was used for the benzannulation of l-phenyl-2-ethynylbenzenes. This approach was implemented in the synthesis of a variety of polycyclic aromatic hydrocarbons including substituted coronenes (53-86% yield) through twofold and fourfold benzannulation [169]. 

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