Synthesis, Structural Characterization and Reactivity of Metal-Carboranyl and Metal-Dicarbollyl Complexes

Late transition metal (M = Co, Ni) complexes bearing linked Cp/Ind/CpCH 2CH2NMe2-carboranyl ligands were synthesized by treatment of the dilithium salts of the ligands with MCl2(PPh 3)2. The M-C(cage) bonds in these complexes were inert toward unsaturated molecules due to the steric hindrance of carboranyl cage. However, the ligand exchange reaction happened between metal complexes and isocyanide, or carbene or phosphines.;The carbon-linked Cp/Ind/C5Me4-dicarbollyl ligands were synthesized by deboration reaction of Me2C(C5H 5)(C2B10H11), Me2C(C 9H7)(C2B10H11) or H 2C(C5Me4H)(C2B10H11 ) with piperidine in EtOH. Treatment of the trisodium salts of ligands with MCl4(THF)2 gave the mixed sandwich metal chloride complexes [{eta5:eta5--R1 2C(R2)(C2B9H10)}MCl 2][Na(DME)3] (R1 = Me, R2 = C5H4, C9H6; R1 = H, R2 = C5Me4; M = Zr, Hf). No neutral species were formed because of the more open coordination sphere and more electron deficiency of the metal centers than those of the corresponding unbridged ones. Neutral amide complexes [eta5:eta5--Me 2C(R2)(C2B9H10)]Zr(NMe 2)(NHMe2) (R2 = C5Me4, C9H6) were produced through amine elimination reaction of ligands with Zr(NMe2)4. Treatment of [{eta 5:eta5--R12C(R 2)(C2B9H10)}MCl2][Na(DME) 3] with RLi (R = Cp, Bn, TMSCH2) afforded the corresponding ionic zirconium alkyl complexes. On the other hand, reaction of the zirconium chloride complexes with R1NLi produced the neutral zirconium amide complexes due to the pchi(N)-dpi(Zr) back-bonding interactions. These zirconocarborane chloride/amide complexes showed modest to good activity in ethylene polymerization after activation with MAO.;Neutral and stable sandwich metallacarborane alkyl/methyl complexes were synthesized by the reaction of 7-(Me2NH)(CH2)2 -7,8-C2B9H11 with (CpR)MMe 3 (R = TMS2, Me5, M = Zr, Hf). The M-C(alkyl or methyl) bonds in these complexes were inert toward alkenes. However mono-insertion of alkynes was observed, and both steric and electronic factors affected the regioselectivity of insertion reaction. For terminal alkynes, either insertion reaction or acid-base reaction proceeded depending upon the substitutents. Insertion of nitriles, isocyanides, carbodiimides, ketones, and RNCS into the M-C bonds was also investigated. In some cases, the sequential insertion and B-H activation were observed.