Understanding Spin Structure in Metallacrown Single-Molecule Magnets using Magnetic Compton Scattering

• Published in: Journal of the American Chemical Society Vol. 136; no. 13; pp. 4889 - 4892
• Main Authors: Deb, Aniruddha, Boron, Thaddeus T, Itou, Masayoshi, Sakurai, Yoshiharu, Mallah, Talal, Pecoraro, Vincent L, Penner-Hahn, James E
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02-04-2014
• Subjects: Crown Compounds - chemistry; Dysprosium - chemistry; Gadolinium - chemistry; Magnetic Phenomena; Magnetics - methods; Magnets - chemistry; Manganese - chemistry; Yttrium - chemistry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja501452w

The 3d–4f mixed metallacrowns frequently show single-molecule magnetic behavior. We have used magnetic Compton scattering to characterize the spin structure and orbital interactions in three isostructural metallacrowns: Gd2Mn4, Dy2Mn4, and Y2Mn4. These data allow the direct determination of the spin only contribution to the overall magnetic moment. We find that the lanthanide 4f spin in Gd2Mn4 and Dy2Mn4 is aligned parallel to the Mn 3d spin. For Y2Mn4 (manganese-only spin) we find evidence for spin delocalization into the O 2p orbitals. Comparing the magnetic Compton scattering data with SQUID studies that measure the total magnetic moment suggests that Gd2Mn4 and Y2Mn4 have only a small orbital contribution to the moment. In contrast, the total magnetic moment for Dy2Mn4 MCs is much larger than the spin-only moment, demonstrating a significant orbital contribution to the overall magnetic moment. Overall, these data provide direct insight into the correlation of molecular design with molecular magnetic properties.