Author:
Semenova Lioubov I.,White Allan H.
Abstract
Room-temperature single-crystal X-ray structural characterizations are
recorded for hydrated lan- thanoid(III)
bromide/2,2′:6′,2″-terpyridine (tpy) (1 : 1) complexes,
showing all to be ionic and of the form
[(tpy)Ln(OH2)x]Br3.yH2O,
where x and y are 6 and 1 for the
isomorphous series Ln = La(-)Er (and intermediate members, by
presumption), and 5 and various values for Ln = Tm, Yb, Lu. Crystals of
[(tpy)Ln(OH2)6]Br3.H2O
are monoclinic, P
21/c, a
≈ 8·5, b ≈ 18, c ≈
16·3 Å, β ≈ 108°, Z = 4;
for Ln = La, Er, conventional R values on
|F| were 0·048, 0·080 for
No 4027, 1347
‘observed’ (I >
3σ(I)) diffractometer reflections respectively.
The complex
[(tpy)Tm(OH2)5]Br3.H2O
is monoclinic, P
21/c, a
8·506(4), b 17·376(1),
c 15·951(6) Å, β 106·87(3)°,
Z = 4, (quasi-)isomorphous with the Ln =
La-Er array, R 0·065 for
No 2067.
[(tpy)Yb(OH2)5]Br3.4H2O
is triclinic, P 1, a
11·902(2), b 11·639(3),
c 9·831(2) Å, α 98·92(2),
β 106·84(2), γ 92·42(2)°, Z
= 2, R 0·062 for
No 3422, while
[(tpy)Lu(OH2)5]Br3.H2O
is monoclinic, P 21/n,
a 13·635(8), b
9·022(5), c 19·03(1) Å, β
99·02(5)°, Z = 4,
R 0·043 for
No 3139. Despite a common
N3LnO5 coordination sphere in the
last three compounds, subtle differences are found in stereochemistry; in the
N3LnO6 array, one of the outer
water molecules becomes progressively detached as the lanthanoid radius
contracts. Some tendency is found toward the end of the lanthanoid series
toward the formation of di(hydroxy-bridged) neutral dimers,
Ln(OH)Br2/tpy/H2O(1 : 1 :
8)(×2),
[(tpy)(H2O)3Ln(µ-OH)2Ln(OH2)3(tpy)]Br4.10H2O,
monoclinic, C 2/c,
a ≈ 19·5, b ≈
14·5, c ≈ 17·1 Å, β ≈
92°, Z = 4 dimers, thus far defined by full
determinations for the extrema Lu = Er, Lu (and Y),
R 0·055, 0·043, (0·047) for
No 3141, 4591, (2991)
respectively; the dimer is disposed about a crystallographic
2 -axis. An Ln = Dy example, seemingly
isomorphous, has also been characterized by cell determination.