Facile pyrazolylborate ligand degradation at lanthanide centers: X-ray crystal structures of pyrazolylborinate-bridged bimetallics.
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.
Domingos
Angela
A
Departamento de Química, ITN, Estrada Nacional 10, 2686-953 Sacavém, Portugal.
Elsegood
Mark R J
MR
Hillier
Anna C
AC
Lin
Guanyang
G
Liu
Sung Ying
SY
Lopes
Irene
I
Marques
Noémia
N
Maunder
Graham H
GH
McDonald
Robert
R
Sella
Andrea
A
Steed
Jonathan W
JW
Takats
Josef
J