Organolanthanoids

Synthesis and Structures of the First Cationic Perfluoroaryllanthanoid(II) Complexes

“…Presumably, these reactions pro- ceed by protolysis of the more basic LnÀPh site of intermediate LnPh(C 6 F 5 ) [14] ) and low temperature crystallization of the filtered and evaporated solution in PhMe/hexane gave a large amount of a dark colored intractable oil (most likely decomposition products) and a small amount of bright yellow 3. An alternative workup procedure by addition of hexanes to the concentrated THF solution gave crystals of [Yb(C 6 [15] [Yb{N(SiMe 3 ) 2 } 2 (thf) 2 ], [16] and [Yb(thf) [15] However, the mixed oxidation state complex 3 has a further intense band at 956 cm À1 , not observed for the Yb II complexes, and this can be assigned to the n(C±F) absorption of the Yb III anion. Similarly, a pair of bands attributable to n(CPC) of the two different fluorocarbon rings is observed near 1500 cm À1 in the spectrum of 3.…”

“…Room-temperature data exhibited [15] and [Yb (C 5 Me 5 )-(C 6 F 5 )(thf) 3 ]. [14] Significantly, the 171 [14] and di-cationic…”

“…In contrast, [Yb(C 6 show near complete decomposition to intractable, dark colored materials within 1±2 days storage at room temperature under nitrogen. [15] After heating a solution of 2 in [D 8 ]THF at 60 8C for 3 h, the 19 F NMR spectrum of the resulting mixture showed a forest of fluoroaromatic resonances in the region d = À140 to À170 ppm with no evidence of any polyfluoroarylytterbium(ii) compound or C 6 F 5 H. Heating a solution of 2 in THF at 60 8C for 24 h gave an amorphous material mixed with a white crystalline solid which was shown to be [Yb II (thf) 6 ][BPh 4 ] 2 [13] by X-ray crystallography. Whilst this observation could be simply explained by disproportionation of 2 (Scheme 3), the absence of dark colored decomposition products argues against the concomitant formation of [Yb(C 6 F 5 ) 2 (thf) 4 ].…”

“…Clearly the thermal reactions of 2 (and presumably also 1) are substantially different to those of other LnÀC 6 F 5 species in which F À abstraction and tetrafluorobenzyne formation are considered to be the key steps (similar to that proposed for Li(C 6 F 5 ) [36] ). [15] Radical-induced decomposition of BPh 4 À is known [37] and homolytic scission of the YbÀC bond would give C 6 [8] ) by a highly Lewis acidic organolanthanoid(iii) cation has recently been reported, [39] and a THF-derived ytterbium(iii) n-buten-2-olate (YbÀOCH 2 CH=CHCH 3 ) fragment has been observed. [40] A ytterbium alkoxide formed by opening of THF would be an effective nucleophile for C 6 F 5 H giving p-HC 6 F 4 X.…”

Intramolecular Metal–Fluorocarbon Coordination, CF Bond Activation and Lanthanoid–Fluoride Clusters with Tethered Polyfluorophenylamide Ligands

“…[16] Indeed it has been shown that S,F-chelated [SmA C H T U N G T R E N N U N G (SC 6 F 5 ) 3 ] yields SmF 3 on heating [11] and C,F-chelated [Ce(C 5 H 2 -tBu 3 -1,2,4) 2 C 6 F 5 ] decomposes into the corresponding fluoride and tetrafluorobenzyne. [4,5] Other cases of lanthanoid induced C À F activation [21] involve actual [22] or postulated [23][24][25] polyfluorophenylor polyfluorobenzoato-lanthanoid complexes [26] that plausibly form C(Ar)-F-Ln interactions as a step in activation. In many cases, lanthanoid-induced C À F activation leads to the formation of heteroleptic fluorides, [4,19,[21][22][23][24][25]27] [Ln(L) 2 F], [Ln(L)F 2 ], or more complex species including cages and rings.…”