High magnetic anisotropy is a key property of paramagnetic shift tags, which are mostly studied by NMR spectroscopy, and of single molecule magnets, for which magnetometry is usually used. We successfully employed both these methods in analyzing magnetic properties of a series of transition metal complexes, the so-called clathrochelates. A cobalt complex was found to be both a promising paramagnetic shift tag and a single molecule magnet because of it having large axial magnetic susceptibility tensor anisotropy at room temperature (22.5 × 10 m mol) and a high effective barrier to magnetization reversal (up to 70.5 cm). The origin of this large magnetic anisotropy is a negative value of zero-field splitting energy that reaches -86 cm according to magnetometry and NMR measurements.

Modern nanophotonics has witnessed the rise of “electric anapoles” (EDAs), destructive interferences of electric and toroidal electric dipoles, actively exploited to resonantly decrease radiation from nanoresonators. However, the inherent duality in Maxwell equations suggests the intriguing possibility of “magnetic anapoles,” involving a nonradiating composition of a magnetic dipole and a magnetic toroidal dipole. Here, a hybrid anapole (HA) of mixed electric and magnetic character is predicted and observed experimentally via dark field spectroscopy, with all the dominant multipoles being suppressed by the toroidal terms in a nanocylinder. Breaking the spherical symmetry allows to overlap up to four anapoles stemming from different multipoles with just two tuning parameters. This effect is due to a symmetry‐allowed connection between the resonator multipolar response and its eigenstates. The authors delve into the physics of such current configurations in the stationary and transient regimes and explore new ultrafast phenomena arising at sub‐picosecond timescales, associated with the HA dynamics. The theoretical results allow the design of non‐Huygens metasurfaces featuring a dual functionality: perfect transparency in the stationary regime and controllable ultrashort pulse beatings in the transient. Besides offering significant advantages with respect to EDAs, HAs can play an essential role in developing the emerging field of ultrafast resonant phenomena.

The title complex ( tBuPCP)­IrH­(Cl) (1; tBuPCP = κ3-2,6-(CH2PtBu2)2C6H3) appeared to be moderately active in NHMe2·BH3 (DMAB) dehydrogenation, allowing the systematic spectroscopic (variable-temperature NMR and IR) investigation of the reaction intermediates and products, under both stoichiometric and catalytic regimes, combined with DFT/M06 calculations. The formation of the hexacoordinate complex (tBuPCP)­IrHCl­(η1-BH3·NHMe2) (3) stabilized by a NH···Cl hydrogen bond is shown experimentally at the first reaction step. This activates both B–H and Ir–Cl bonds, initiating the precatalyst activation and very first DMAB dehydrogenation cycle. The same geometry is suggested by the DFT calculations for the key intermediate of the catalytic cycle, (tBuPCP)­IrH2(η1-BH3·NHMe2) complex (6). In these complexes, DMAB is coordinated trans to the ipso carbon, allowing the steric repulsion between the amine–borane and tert-butyl groups at the phosphorus atoms to be overcome. Under catalytic conditions (2–5 mol % of 1) the hydride complex (tBuPCP)­IrH­(μ2-H2BH2) (5) was identified, which is not a dormant catalytic species but the steady-state intermediate formed as a result of the B–N bond breaking. DMAB dehydrogenation yields the borazane monomer H2BNMe2 (detected by 11B NMR); dimerization of this species gives the final product [H2BNMe2]2 and (tBuPCP)­IrH4 as the catalyst resting state. The scenario of B–N bond cleavage in DMAB leading to byproducts of dehydrogenation such as bis­(dimethylamino)­hydroborane and (tBuPCP)­IrH­(μ2-H2BH2) (5) is proposed. The results obtained allow us to suggest the mechanism of catalytic DMAB dehydrocoupling that could be generalized to other processes.

The Ir III hydride ( tBu PCN)IrHCl (1) containing the tridendate unsymmetrical pincer ligand tBu PCN − { tBu PCN(H) = 1-[3-[(ditert-butylphosphino)methyl]phenyl]-1H-pyrazole} has been exploited as ammonia borane (NH 3 BH 3 , AB) and amine boranes dehydrogenation catalyst in THF solution at ambient temperature. 1 releases one H 2 equivalent per AB equivalent, with concomitant cyclic poly(aminoboranes) formation [B-(cyclotriborazanyl)-amine-borane (BCTB) and cyclotriborazane (CTB)] as the final "spent fuel". 1 has been found to have superior catalytic activity than its symmetrical analogue ( tBu PCP)IrHCl, with recorded TOF values of 580 h −1 (AB in THF) and 401 h −1 (DMAB in toluene) at ambient temperature. The reaction has been analyzed experimentally through multinuclear [ 11 B, 31 P{ 1 H}, 1 H] NMR and IR spectroscopy, kinetic rate measurements, and kinetic isotope effect determination with deuterated AB isotopologues. The hydride/borohydride intermediate ( tBu PCN)IrH(η 2 -BH 4 ) (2) is the catalyst resting state formed during the dehydrogenation process; it is detected by a variable-temperature multinuclear NMR of the reaction course (in the 190−323 K range). A DFT modeling of the reaction mechanism using DMAB as substrate has been performed with the geometry optimization in toluene at the M06 level of theory. The combination of the kinetic and computational data reveals that a simultaneous B−H/N−H activation occurs in the presence of 1, after the preliminary amine borane coordination to the metal center.

Herein, we report a new trigonal prismatic cobalt(II) complex that behaves as a single molecule magnet. The obtained zero‐field splitting, which is also directly accessed by THz‐EPR spectroscopy (−102.5 cm−1), results in a large magnetization reversal barrier U of 205 cm−1. Its effective value, however, is much lower (101 cm−1), even though there is practically no contribution from quantum tunneling to magnetization relaxation.