Cyclopentadienyl Free Compounds of p, d, and f Elements

Abstract

One of the main objectives of this dissertation was to establish a general route to the Cp-free bis-hydrocarbyl complexes for the 4f metals, LLnR2. Taking into account both the Lewis acidic nature of the lanthanide cations and the desired goal, the monoanionic ligand L: L = [N,N''-(1,3-dimethyl-1,3-propanediylidene)bis[N',N'-diethyl-1,2-ethanediamine]] was designed in order to prevent salt occlusion, dimerization, THF ligation, and ligand redistribution (the ligand must be non-labile). Once the conjugated acid of the ligand L was obtained, its lithiation gave rise to a rich chemistry with main group metals, transition metals, and lanthanides such as LPrCl2 or LTbBr2 On the other hand the metathesis reactions proved to be difficult depending very much on the reaction conditions. Hence, only LTb(CH2SiMe3)2, could be prepared by salt elimination, and it was fully characterized. Additionally, it has been revealed that these precursors could undergo other metathesis reactions, for instance with NaBH4. The versatility of the ligand L has been illustrated by the augmentation of its chemistry with complexes of aluminum and vanadium. For instance, straightforward complexes like LAlCl2, LAlMe2, or LVCl2 have been effortlessly prepared. Furthermore, a precursor like LAlMe2 afforded, when reacted with the strong Brønsted acid H2O·B(C6F5)3, under different reactions conditions, the first monoaluminoxane and its isomer. The attempt to prepare an aluminum imide by the reaction of LAlMe2 and H3N·B(C6F5)3 resulted in complex LAl(Me)NH2·B(C6F5)3 the intermediary step on the way to the desired aluminum imide. Whereas efforts in developing the b-diketiminates of aluminum are considerable, not the same applies to metals like titanium, vanadium, or chromium. Accordingly, some complexes of vanadium with the L ligand system have been prepared: LV(OSO2CF3)2, the first vanadium(III) triflate derivative structurally characterized, und the first neutral terminal heteroleptic diorganophosphido-complex of vanadium(II) and the first structurally characterized terminal phosphido complex of vanadium LVPPh2. The quest for a new monoanionic b-diketiminato based ligand, which was a main objective, emerged when the failure of the L ligand system became evident if applied for the second and third row of the late transitional metals. As a result a new ligand L' = [N,N'-(1,3-dimethyl-1,3-propanediylidene)bis[2-diphenylphosphanyl-ethylamine]]- that incorporates phosphorus donors instead of the previous nitrogen donors and its synthesis was carried out. The in situ prepared potassium salt, L'K reacted easily with [m-ClRh(CO)2]2 under formation of a very stable rhodium(I) complex but with YCl3 , L'2YCl was obtained.