Cationic rare-earth-metal methyl complexes: a new preparative access exemplified for Y and Pr.
A new procedure for the generation of cationic methyl complexes of rare-earth metals has been developed for yttrium and praseodymium as two examples from the rare-earth series. The reactions of the rare-earth-metal tetramethylaluminates [Ln(AlMe(4))(3)] of yttrium and praseodymium with three differently sized crown ethers in thf, namely [12]crown-4, [15]crown-5 and [18]crown-6, respectively, led to the compounds [YMe([12]crown-4)(2)](2+)[AlMe(4)](-)(2) (1), [PrMe([12]crown-4)(2)](2+)[AlMe(4)](-)(2) (2), [YMe([15]crown-5)(thf)(2)](2+)[AlMe(4)](-)(2) (3), [Pr([15]crown-5)(2)](3+)[AlMe(4)](-)(3) (4), [YMe([18]crown-6)(thf)](2+)[AlMe(4)](-)(2) (5) and [PrMe([18]crown-6)(thf)(2)](2+) [AlMe(4)](-)(2) (6). With the exception of 4, all compounds contain molecular di-cations with a Ln-CH(3) unit bonded to one (3, 4, 6) or two (1, 2) crown-ether molecules. The compounds were characterised by determination of their crystal structures, by elemental analyses and in the case of the yttrium compounds by variable temperature NMR spectroscopy. The latter gives insights into molecular dynamic processes and methyl group exchange between cations and anions in solution.
Nieland
Anja
A
Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, 33615, Bielefeld, Germany.
Mix
Andreas
A
Neumann
Beate
B
Stammler
Hans-Georg
HG
Mitzel
Norbert W
NW