A new convenient preparation of monocyclooctatetraenyl-lanthanide complexes from metallic lanthanides and oxidants

Article abstract of DOI:10.1016/0022-328X(94)80108-8

Treatment of lanthanide metals with cyclooctatetraene in the presence of an equimolar amount of iodine afforded cyclooctatetraenyl-iodolanthanide(III) complexes, LnI(η⁸-cot)(thf)n (cot = cyclooctatetraenyl; 1a: Ln = La, n = 3; 1b: Ln = Ce, n = 3; 1c: Ln = Pr, n = 3; 1d: Ln = Nd; n = 2; 1e: Ln = Sm, n = 1), in modest yields.Bromo and chloro-bridged dinuclear complexes of samarium, 2 (2: X = Br; 3: X = Cl), are also prepared by the reaction of samarium metal with cyclooctatetraene in the presence of 1,2-dibromoethane or Ph3PCl2, respectively.The reaction of metallic samarium with cyclooctatetraene and diaryl disulfide or diphenyl diselenide in THF afforded cyclooctatetraenyl-thiolate or - selenolate complexes of samarium(III), 8-cot)(thf)n>2 (4a: EAr = SPh, n = 2; 4b: SC6H2Me3-2,4,6, n = 2; 4c: SC6H2ⁱPr3-2,4,6, n = 1; 5: SePh, n = 2).The dimeric structure of 5 was revealed by X-ray crystallography 1/n with a = 8.500(5), b = 21.805(6), c = 12.042(5) Angstroem, β = 105.98(4) deg, V = 2145(1) Angstroem³, Z = 2, R = 0.055 for 2061 reflections with I > 3?(I) and 235 parameters>.A samarium(II) complex, 8-cot)(thf)>n (6), was also obtained by the direct reaction of samarium metal with cyclooctatetraene in THF with a catalytic amount of iodine.Reaction of 6 with iodine and diphenyl disulfide afforded 1e and 4a, respectively. Key words: Lanthanide; Cyclooctatetraenyl; Thiolate; Selenolate; Samarium