title: Facile pyrazolylborate ligand degradation at lanthanide centers: X-ray crystal structures of pyrazolylborinate-bridged bimetallics.
abstract: Adventitious hydrolysis of a number of different complexes with the molecular formula Ln(Tp(Me2))(2)X [Tp(Me2) = (HB(dmpz)(3)), where X is a basic anionic ligand] in various solvents, yielded crystals of highly insoluble dimers of the general formula [Ln(Tp(Me2))(mu-BOp(Me2))](2) (1) [Ln = La, Ce, Sm; BOp(Me2) = (HBO(dmpz)(2))(2)(-); dmpzH = 3,5-dimethylpyrazole]. The results of several single-crystal X-ray determinations are reported. One metal nitrogen distance, that lying across from the two negatively charged bridging oxygen atoms, is 0.06 A longer than the others, suggesting an unusual trans influence at a lanthanide center. The formation of 1 is proposed to involve the intermediacy of Ln(Tp(Me2))(2)OH formed by protonolysis with adventitious water.
authors.affiliation: Departamento de Química, ITN, Estrada Nacional 10, 2686-953 Sacavém, Portugal.
authors.forename: Angela
authors.initials: A
authors.lastname: Domingos
authors.forename: Mark R J
authors.initials: MR
authors.lastname: Elsegood
authors.forename: Anna C
authors.initials: AC
authors.lastname: Hillier
authors.forename: Guanyang
authors.initials: G
authors.lastname: Lin
authors.forename: Sung Ying
authors.initials: SY
authors.lastname: Liu
authors.forename: Irene
authors.initials: I
authors.lastname: Lopes
authors.forename: Noémia
authors.initials: N
authors.lastname: Marques
authors.forename: Graham H
authors.initials: GH
authors.lastname: Maunder
authors.forename: Robert
authors.initials: R
authors.lastname: McDonald
authors.forename: Andrea
authors.initials: A
authors.lastname: Sella
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Steed
authors.forename: Josef
authors.initials: J
authors.lastname: Takats