Assessing crystal field and magnetic interactions in diuranium-μ-chalcogenide triamidoamine complexes with UIV–E–UIV cores (E = S, Se, Te): implications for determining the presence or absence of actinide–actinide magnetic exchange. Issue 9 (12th July 2017)

• Record Type: Journal Article
• Authors: Gardner, Benedict M.; King, David M.; Tuna, Floriana; Wooles, Ashley J.; Chilton, Nicholas F.; Liddle, Stephen T.
• Is Part Of: Chemical science. Volume 8:Issue 9(2017)
• Page Start: 6207
• Page End: 6217
• Publication Date: 2017-07-12
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7sc01998j
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Analysis of U IV –E–U IV (E = S, Se, Te) complexes reveals their behaviour is due to crystal field effects and not exchange coupling. Abstract : We report the synthesis and characterisation of a family of diuranium(iv )-μ-chalcogenide complexes including a detailed examination of their electronic structures and magnetic behaviours. Treatment of [U(Tren TIPS )] [1, Tren TIPS = N(CH2 CH2 NSiPr i 3 )3 ] with Ph3 PS, selenium or tellurium affords the diuranium(iv )-sulfide, selenide, and telluride complexes [{U(Tren TIPS )}2 (μ-E)] (E = S, 2 ; Se, 5 ; Te, 6 ). Complex2 is also formed by treatment of [U(Tren TIPS ){OP(NMe2 )3 }] (3 ) with Ph3 PS, whereas treatment of3 with elemental sulfur gives the diuranium(iv )-persulfido complex [{U(Tren TIPS )}2 (μ-η 2 :η 2 -S2 )] (4 ). Complexes2–6 have been variously characterised by single crystal X-ray diffraction, NMR, IR, and optical spectroscopies, room temperature Evans and variable temperature SQUID magnetometry, elemental analyses, and complete active space self consistent field spin orbit calculations. The combined characterisation data present a self-consistent picture of the electronic structure and magnetism of2, 5, and6, leading to the conclusion that single-ion crystal field effects, and not diuranium magnetic coupling, are responsible for features in their variable-temperature magnetisation data. The presence of magnetic coupling is often implied and sometimes quantified by such data, and so this study highlights the importance of evaluating other factors, such as crystal field effects, that can produce similar magnetic observables, and to thus avoid misassignments of such phenomena.