RESUMO
Monomeric, divalent ytterbium primary amides TptBu,MeYb(NHR)(thf)x (R = C6H3iPr2-2,6 = AriPr = Dipp, C6H3(CF3)2-3,5 = ArCF3, SiPh3) supported by the bulky hydrotris(3-tBu-5-Me-pyrazolyl)borato scorpionate ligand are synthesized acccording to salt metathesis and protonolysis protocols, respectively. Yb(II) precursors comprise YbI2(thf)2, Yb[N(SiMe3)2]2(thf)2 and TptBu,MeYb[N(SiMe3)2]. Complexes TptBu,MeYb(NHR)(thf)x readily engage in donor (thf) exchange with nitrogen donors like DMAP (4-dimethylaminopyridine) and pyridine. Treatment of TptBu,MeYb(NHArCF3)(thf)2 with the Lewis acids AlMe3 and GaMe3 results in the heterobimetallic complexes TptBu,MeYb(NHArCF3)(MMe3) (M = Al, Ga). Reactions of TptBu,MeYb(NHR)(thf)x (R = AriPr, ArCF3) with the halogenating agents C2Cl6 and TeBr4 give access to trivalent complexes [TptBu,MeYb(NHR)(X)] (X = Cl, Br). The ytterbium(II) complexes under study display 171Yb NMR chemical shifts in the range 582 ppm for TptBu,MeYb(NHArCF3)(GaMe3) to 954 ppm for TptBu,MeYb(NHSiPh3)(dmap). The salt-metathesis route is also applicable for the synthesis of complexes TptBu,MeLn(NHAriPr)(thf) (Ln = Sm, Eu) and TptBu,MeYb(NHArMe) (ArMe = C6H3Me2-2,6).
RESUMO
Divalent ytterbium bis(trimethylsilyl)amides [Yb{N(SiMe3)2}2]2 and Yb[N(SiMe3)2]2(thf)2 react with purified methyllithium to amorphous dimethylytterbium [YbMe2]n. The characterisation was performed by 171Yb and 13C CP/MAS NMR spectroscopy as well as by conducting protonolysis reactions with HC5Me5 and HTptBu,Me, affording known (C5Me5)2Yb(OEt2) and new (TptBu,Me)Yb(CH3)(thf).
RESUMO
Treatment of dimethylmagnesium with dimethylaluminum hydride in common ethereal solvents led to the bimetallic monomagnesium addition compounds [(do)xMg{(µ2-H)(AlMe3)}2] (do = thf, x = 4, do = Et2O, x = 3; do = dme, x = 2). Utilization of methyl tert-butyl ether (mtbe) resulted in alkyl/hydrido overexchange and formation of an 8-membered ring structure of composition [(mtbe)2Mg{(µ2-H)(AlMe3)(µ2-H)(µ2-H)(AlMe2)}]2. Salt metathesis of [(thf)4Mg{(µ2-H)(AlMe3)}2] with potassium 1,2,3,4,5-pentamethyl-cyclopentadienide (KCp*) gave [Cp*Mg{(µ2-H)(AlMe3)}(thf)2] featuring a rare isolable magnesium half-sandwich hydride complex. Furthermore, magnesium hydride-inherent reactivity was proven for [(thf)4Mg{(µ2-H)(AlMe3)}2] by the selective reduction of pyridine to 1,4-dihydropyridide (1,4-DHP) at ambient temperature and the hydromagnesiation of 1-hexene in the absence of any transition metal catalyst (low conversion).
