title: Lanthanide metallocene complexes of the 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinato Ligand, (hpp)1-.
abstract: Reaction of the lanthanide metallocene allyl complexes, (C(5)Me(5))(2)Ln(eta(3)-CH(2)CHCH(2))(THF) (Ln = Ce, Sm, Y) with 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, Hhpp, forms a series of metallocene complexes, (C(5)Me(5))(2)Ln(hpp) (Ln = Ce, Sm, Y) in which the (hpp)(1-) anion coordinates as a terminal bidentate ligand. Isomorphous structures were observed by X-ray crystallography regardless of the size of the metal. The acetonitrile adduct, (C(5)Me(5))(2)Sm(hpp)(MeCN), was also crystallographically characterized to provide an unusual pair of eight- and nine-coordinate complexes. The coordination mode of the (hpp)(1-) anion in these complexes is compared with that in other heteroallylic metallocenes like the caprolactamate (C(5)Me(5))(2)Y(ONC(6)H(10)) and the dithiocarbamate (C(5)Me(5))(2)Sm(S(2)CNEt(2)), which was also structurally characterized.
authors.affiliation: Department of Chemistry, University of California, Irvine, California 92697-2025, USA. wevans@uci.edu
authors.forename: William J
authors.initials: WJ
authors.lastname: Evans
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Montalvo
authors.forename: Dustin J
authors.initials: DJ
authors.lastname: Dixon
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Ziller
authors.forename: Antonio G
authors.initials: AG
authors.lastname: Dipasquale
authors.forename: Arnold L
authors.initials: AL
authors.lastname: Rheingold