| Cationic 14-electron metal-alkyl complexes [(η5-C 5H5)2M-R]+ (M = Ti, Zr, Hf) have been established as the active species in homogeneous polymerization of olefins. Our research interests have focused on gaining some control over ion pairing between the metal cation and its anion, by covalently linking a borate anion to the ligand backbone of the transition metal complex. One approach to accomplishing this goal is to prepare a zwitterion, where the charges are physically separated by covalently linking the borate counterion to the ligand backbone of the catalyst. Our methods involve the building of a robust B-C bond that will remain intact during the polymerization process. The reaction of Li2 [(CH3)4C5(Si(CH3)2 (p-C6F4-B(C6F5)3], (Li2[CpB]) with (C5H5)ZrCl 3 produces an anionic sandwich complex Li[(C5H5)(CP B)ZrCl2]. This complex is an active ethylene polymerization catalyst once activated with MAO. The preparation of ligands and the X-ray crystal structure of an anionic metallocene Li[ZrCl2(C 5H5)-(C5(CH3)4-Si(CH 3)2-C6F4-p-B(C 6F5)3] ·2(i-Pr2O) are discussed.; Catalytic oxidation of hydrocarbons can be accomplished by employing homogeneous iron salts. One substrate of particular interest is cyclohexane and its higher oxidation products cyclohexanol (A) and cyclohexanone (K). We have developed a system in which the oxidation of cyclohexane can be accomplished by the addition of Iron (II) or Iron (III) salts in neat cyclohexane solution under mild conditions. The system development and optimization of the process is discussed. |
