Strong exchange coupling in lanthanide bis-(phthalocyaninato) sandwich compounds

Journal Article · Mon Apr 15 04:00:00 EDT 1991 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.347794· OSTI ID:5769408

Trojan, K L; Hatfield, W E; Kepler, K D; Kirk, M L ^[1]

---

1. Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290 (US)

Bis (phthalocyaninato) lanthanide sandwich compounds, which have the formula Pc{sup 2-}LnPc{sup 1-}, have been synthesized for Ln=terbium, holmium, and lutecium. Low-temperature magnetic susceptibility data for Ho(Pc){sub 2} and Tb(Pc){sub 2} show a reduction in moment from that which is expected for the lanthanide free ion value, which correlates with an antiferromagnetic exchange between the lanthanide {ital f} electrons and the phthalocyaninato ligand radical electron. The {ital g} factors determined from least-squares fitting of the Curie--Weiss law to the magnetic data show excellent agreement to the {ital g} factors calculated for the strongly coupled state. Magnetic moments calculated from the experimentally determined Curie constants are also in good agreement with those expected for the strongly coupled state. Low-temperature magnetic susceptibility data for Lu(Pc){sub 2} follows the Curie--Weiss law with a limiting moment of 1.8 {mu}{sub {ital B}} at 100 K. Since lutecium has a {sup 1}{ital S}{sub 0} ground state, only the phthalocyanine(1-) ligand would be expected to contribute to the magnetic susceptibility in this system. Room-temperature electron paramagnetic resonance measurements show no transitions at or near {ital g}=2, indicative of a free radical, due to the strong antiferromagnetic coupling of the ligand radical electron with the lanthanide {ital f} electrons. In the case of LuPc{sub 2}, where no unpaired {ital f} electrons exist, a transition at {ital g}=2.00 is present.

• OSTI ID: 5769408
• Journal Information: Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Vol. 69:8; ISSN 0021-8979; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ANTIFERROMAGNETISM
COUPLING
CURIE POINT
DYES
HETEROCYCLIC COMPOUNDS
HOLMIUM COMPOUNDS
LUTETIUM COMPOUNDS
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
MAGNETISM
ORGANIC COMPOUNDS
PHTHALOCYANINES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
TERBIUM COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE