ic991170j_si_002.pdf (1.03 MB)
Homotrinuclear Lanthanide(III) Arrays: Assembly of and Conversion from Mononuclear and Dinuclear Units†
journal contribution
posted on 2000-01-15, 00:00 authored by Ika A. Setyawati, Shuang Liu, Steven J. Rettig, Chris OrvigThe reactions of potentially hexadentate H2bbpen (N,N ‘-bis(2-hydroxybenzyl)-N,N ‘-bis(2-pyridylmethyl)ethylenediamine, H2L1), H2(Cl)bbpen (N,N ‘-bis(5-chloro-2-hydroxybenzyl)-N,N ‘-bis(2-pyridylmethyl)ethylenediamine, H2L2), and H2(Br)bbpen (N,N ‘-bis(5-bromo-2-hydroxybenzyl)-N,N ‘-bis(2-pyridylmethyl)ethylenediamine,
H2L3) with Ln(III) ions in the presence of a base in methanol resulted in three types of complexes: neutral
mononuclear ([LnL(NO3)]), monocationic dinuclear ([Ln2L2(NO3)]+), and monocationic trinuclear ([Ln3L2(X)n(CH3OH)]+), where X = bridging (CH3COO-) and bidentate ligands (NO3-, CH3COO-, ClO4-) and n is 4. The
formation of a complex depends on the base (hydroxide or acetate) and the size of the respective Ln(III) ion. All
complexes were characterized by infrared spectroscopy, mass spectrometry, and elemental analyses; in some
cases, X-ray diffraction studies were also performed. The structures of the neutral mononuclear [Yb(L1)(NO3)],
dinuclear [Pr2(L1)2(NO3)(H2O)]NO3·CH3OH and [Gd2(L1)2(NO3)]NO3·CH3OH·3H2O, and trinuclear [Gd3(L3)2(CH3COO)4(CH3OH)]ClO4·5CH3OH and [Sm3(L1)2(CH3COO)2(NO3)2(CH3OH)]NO3·CH3OH·3.65H2O were solved
by X-ray crystallography. The [LnL(NO3)] or [Ln2L2(NO3)]+ complexes could be converted to [Ln3L2(X)n(CH3OH)]+ complexes by the addition of 1 equiv of a Ln(III) salt and 2−3 equiv of sodium acetate in methanol. The
trinuclear complexes were found to be the most stable of the three types, which was evident from the presence
of the intact monocationic high molecular weight parent peaks ([Ln3L2(X)n]+) in the mass spectra of all the
trinuclear complexes and from the ease of conversion from the mononuclear or dinuclear to the trinuclear species.
The incompatibility of the ligand denticity with the coordination requirements of the Ln(III) ions was proven to
be a useful tool in the construction of multinuclear Ln(III) metal ion arrays.