Thomas Pugh

A Low-Symmetry Dysprosium Metallocene Single-Molecule Magnet with a High Anisotropy Barrier.

The single-molecule magnet (SMM) properties of the isocarbonyl-ligated dysprosium metallocene [Cp*2 Dy{μ-(OC)2 FeCp}]2 (1Dy ), which contains a rhombus-shaped Dy2 Fe2 core, are described. Combining a strong axial [Cp*](-) ligand field with a weak equatorial field consisting of the isocarbonyl ligands leads to an anisotropy barrier of 662 cm(-1) in zero applied field. The dominant thermal relaxation pathways in 1Dy involves at least the fourth-excited Kramers doublet, thus demonstrating that prominent SMM behavior can be observed for dysprosium in low-symmetry environments.

Iron- and Cobalt-Catalyzed Synthesis of Carbene Phosphinidenes

Abstract In the presence of stoichiometric or catalytic amounts of [M{N(SiMe3)2}2] (M=Fe, Co), N‐heterocyclic carbenes (NHCs) react with primary phosphines to give a series of carbene phosphinidenes of the type (NHC)⋅PAr. The formation of (IMe4)⋅PMes (Mes=mesityl) is also catalyzed by the phosphinidene‐bridged complex [(IMe4)2Fe(μ‐PMes)]2, which provides evidence for metal‐catalyzed phosphinidene transfer.

Yttrium Complexes of Arsine, Arsenide, and Arsinidene Ligands

Deprotonation of the yttrium–arsine complex [Cp′3Y{As(H)2Mes}] (1) (Cp′=η5-C5H4Me, Mes=mesityl) by nBuLi produces the μ-arsenide complex [{Cp′2Y[μ-As(H)Mes]}3] (2). Deprotonation of the As–H bonds in 2 by nBuLi produces [Li(thf)4]2[{Cp′2Y(μ3-AsMes)}3Li], [Li(thf)4]2[3], in which the dianion 3 contains the first example of an arsinidene ligand in rare-earth metal chemistry. The molecular structures of the arsine, arsenide, and arsinidene complexes are described, and the yttrium–arsenic bonding is analyzed by density functional theory.

Strong Exchange Coupling in a Trimetallic Radical‐Bridged Cobalt(II)‐Hexaazatrinaphthylene Complex

Abstract Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18‐c‐6 produces [{K(18‐c‐6)}HAN], which contains the S=1/2 radical [HAN].−. The [HAN].− radical can be transferred to the cobalt(II) amide [Co{N(SiMe3)2}2], forming [K(18‐c‐6)][(HAN){Co(N′′)2}3]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt–ligand antiferromagnetic exchange and J≈−290 cm−1 (−2 J formalism). In contrast, the CoII centres in the unreduced analogue [(HAN){Co(N′′)2}3] are weakly coupled (J≈−4.4 cm−1). The finding that [HAN].− can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks.

Magnetic frustration in a hexaazatrinaphthylene-bridged trimetallic dysprosium single-molecule magnet

The synthesis, structure and magnetic properties of the HAN-bridged tri-dysprosium complex [{(thd)3Dy}3HAN] (1) are described. The complex is an SMM that shows two relaxation processes owing to the presence of two geometrically distinct Dy3+ sites in 1. Ab initio calculations reveal that the magnetic ground state of 1 is characterized by magnetic frustration.

CCDC 1484572: Experimental Crystal Structure Determination

Related Article: Thomas Pugh, Nicholas F. Chilton, Richard A. Layfield|2017|Chemical Science|8|2073|doi:10.1039/C6SC04465D

CCDC 1448295: Experimental Crystal Structure Determination

Related Article: Jani O. Moilanen, Nicholas F. Chilton, Benjamin M. Day, Thomas Pugh, Richard A. Layfield|2016|Angew.Chem.,Int.Ed.|55|5521|doi:10.1002/anie.201600694