The interplay between spin densities and magnetic superexchange interactions: case studies of mono- and trinuclear bis(oxamato)-type complexes

Abstract

For future molecular spintronic applications the possibility to modify and tailor the magnetic properties of transition-metal complexes is very promising. One of such possibilities is given by the countless derivatization offered by carbon chemistry. They allow for altering chemical structures and, in doing so, to tune magnetic properties of molecular spin-carrying compounds. With emphasis on the interplay of the spin density distribution of mononuclear and magnetic superexchange couplings of trinuclear bis(oxamato)-type complexes we review on efforts on such magneto-structural correlations.

Effect of the Diamagnetic Single-Crystalline Host on the Angular-Resolved Electron Nuclear Double Resonance Experiments: Case of Paramagnetic [nBu4N]2[Cu(opba)] Embedded in Diamagnetic [nBu4N]2[Ni(opba)]

“…The diamagnetic analog with Ni­(II) instead of Cu­(II) is also available in the form of [ n Bu 4 N] 2 [Ni­(opba)], and both compounds can be cocrystallized . The mixed single-crystal MIX studied in the present work comprises 1% of [ n Bu 4 N] 2 [Cu­(opba)] imbedded in the host lattice of [ n Bu 4 N] 2 [Ni­(opba)] …”

“…19,21−23 The paramagnetic Cu(II) ion in M1 is coordinated by pairwise linked two nitrogen and two oxygen donor atoms (Figure 1b). The 23 Since the MIX crystal lacks an explicit crystal habit, to orient it such that the magnetic field H is normal to the xy-plane of M1 (i.e., H||z-axis) (Figure 1b), detailed measurements of the angular dependences of the ESR spectra were carried out at T = 20 K. The H||z-axis geometry can be identified by the maximum extent of the ESR spectrum. In Figure 2a Cu nuclear spins I = 3/2.…”

“…The mononuclear [ n Bu 4 N] 2 [Cu­(opba)] complex composed of the magnetic core [Cu­(opba)] 2– ( M1 ) and the counterion [ n Bu 4 N] + ( L1 ) is of a substantial interest as a precursor for the synthesis of magnetic polynuclear complexes with a large structural variability. − B. Bräuer et al studied this complex before with ESR and ENDOR in a powder form and solution, consequently determined the g -tensor and the hyperfine (HF) tensors A 63 Cu and A 14 N . On this basis, the spin density on the central metal ion and the ligands was estimated, providing a clue to evaluate magnetic superexchange pathways in the respective polynuclear complexes. ,− The paramagnetic Cu­(II) ion in M1 is coordinated by pairwise linked two nitrogen and two oxygen donor atoms (Figure b). The L1 2 M1 complex forms well-ordered single crystals.…”

Towards molecular spintronics

“…In this Thematic Series we summarize selected examples of the collaborative work in which at least two groups were involved. The range of considered molecules spans from heterotrinuclear bis(oxamato)-type and bis(oxamidato)-type complexes [ 1 – 3 ], to exchange-coupled dinickel complexes [ 4 ], metallo-phthalocyanines [ 5 – 7 ], metallo-porphyrins [ 8 – 9 ] and charge-transfer complexes [ 10 – 11 ], to metal-free molecules like pentacene-derivatives [ 12 ], fullerenes [ 13 ], trimesic acid [ 14 ], or organic ferromagnets [ 15 ]. Besides the internal cooperation, the Research Unit greatly profited from excellent talks and thorough discussions with external guests joining our scientific workshops and we are happy to host six articles from our invited guests with topics beyond the molecular systems investigated in our Research Unit, for example: theoretical predictions on metal/C 60 interfaces [ 16 ], magneto-resistive donor/acceptor transistors [ 17 ], spin-crossover complexes [ 18 ], ferromagnetic thin films obtained from organic blends [ 19 ], and theoretical calculations on 2D porphyrin-based networks for spintronics [ 20 ].…”