Coaggregation of Paramagnetic d- and f-Block Metal Ions with a Podand-Framework Amine Phenol Ligand

• Published in: Inorganic chemistry Vol. 39; no. 3; pp. 508 - 516
• Main Authors: Xu, Zhiqiang, Read, Paul W., Hibbs, David E., Hursthouse, Michael B., Abdul Malik, K. M., Patrick, Brian O., Rettig, Steven J., Seid, Mehran, Summers, David A., Pink, Maren, Thompson, Robert C., Orvig, Chris
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 07-02-2000
• Subjects: Amines - chemistry; Contrast Media - chemistry; Ligands; Magnetics; Metals, Rare Earth - chemistry; Models, Molecular; Molecular Structure; Nickel - chemistry; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Phenols - chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic991171b

This report covers initial studies in the coaggregation of nickel (Ni2+) and lanthanide (Ln3+) metal ions to form complexes with interesting structural and magnetic properties. The tripodal amine phenol ligand H3tam (1,1,1-tris(((2-hydroxybenzyl)amino)methyl)ethane) is shown to be particularly accommodating with respect to the geometric constraints of both transition and lanthanide metal ions, forming isolable complexes with both of these ion types. In the solid-state structure of [Ni(H2tam)(CH3CN)]PF6·2.5CH3CN·0.5CH3OH (1), the Ni(II) center has a distorted octahedral geometry, with an N3O2 donor set from the [H2tam]- ligand and a coordinated solvent (acetonitrile) occupying the sixth site. The reaction of stoichiometric amounts of H3tam with the Ni(II) ion in the presence of lanthanide(III) ions provides [LnNi2(tam)2]+ cationic complexes which contain coaggregated metal ions. These complexes are isolable and have been characterized by a variety of analytical techniques, with mass spectrometry proving to be particularly diagnostic. The solid-state structures of [LaNi2(tam)2(CH3OH)1/2(CH3CH2OH)1/2(H2O)]ClO4·0.5CH3OH·0.5CH3CH2OH·4H2O (2), [DyNi2(tam)2(CH3OH)(H2O)]ClO4·CH3OH·H2O (6), and [YbNi2(tam)2(H2O)]ClO4·2.58H2O (9) have been determined. Each complex contains two octahedral Ni(II) ions, each of which is encapsulated by the ligand tam3- in an N3O3 coordination sphere; each [Ni(tam)]- unit caps the lanthanide(III) ion via bridging phenoxy oxygen donor atoms. In 2, La3+ is eight-coordinated, while in 6, Dy(III) is seven- (to “weakly eight-”) coordinated, and Yb(III) in 9 has a six-coordination environment. The complexes are symmetrically different, 2 possessing C 2 symmetry and 6 and 9 having C 1 symmetry. Magnetic studies of 2, 6, and 9 indicate that antiferromagnetic exchange coupling between the Ni(II) and Ln(III) ions increases with decreasing ionic radius of Ln(III).