Rational Design of Electronically Labile Dinuclear Fe and Co complexes with 1,10-Phenanthroline-5,6-Diimine: A DFT study

A series of coordination compounds of redox-active 1,10-phenanthroline-5,6-diimine with Co^II bis-diketonates and Fe^II dihydrobis(pyrazolyl)borates has been computationally designed by means of density functional theory (DFT UB3LYP*/6-311++G(d,p)) calculations of their electronic structure, energy characteristics, and magnetic properties. Four types of complexes differing by the nature and position of the terminal metal-centered fragments have been considered. The performed systematic calculations have revealed the systems capable of undergoing thermally initiated spin-state switching rearrangements, including those governed by the synchronized mechanisms of spin crossover and valence tautomerism. The predicted magnetic characteristics allow one to consider the dinuclear cobalt complexes and heterometallic Co/Fe compounds with 1,10-phenanthroline-5,6-diimine as building blocks for molecular and quantum electronics devices. © 2019 Wiley Periodicals, Inc.

Hybrid materials of Ni NP@MOF prepared by a simple synthetic method

We demonstrate a novel, simple synthetic method for metal (Ni) NPs in a MOF using the partial thermal decomposition of nickel(II) 2,5-dihydroxyterephthalate (Ni-MOF-74). The Ni NPs inside the Ni-MOF-74 are several nanometers in size, and the size can be precisely controlled by the heating conditions.

Theoretical modeling of valence tautomeric dinuclear cobalt complexes. Adducts of CoII diketonates with cyclic redox-active tetraone ligands

B3LYP*/6-311++G(d,p) calculated two-step VT rearrangement of a Co(ii) diketonate and a pyrene-4,5,9,10-tetraone 2 : 1 adduct occurs with the migration of paramagnetic centers.

Valence tautomeric dinuclear adducts of Co(ii) diketonates with redox-active diquinones for the design of spin qubits: computational modeling

DFT calculations performed on dinuclear adducts of Co(ii) diketonates with redox-active diquinones showed that with the proper structural tuning of the ligands, these paramagnetic complexes possess the properties required in a 2-qubit molecular system.

Photoswitchable stable charge-distributed states in a new cobalt complex exhibiting photo-induced valence tautomerism

We report the synthesis and magnetic and photomagnetic behaviour of a novel valence tautomeric cobalt complex, [Co(3,5-dbbq)₂(μ-bpym)] (1) (3,5-dbbq = 3,5-di-tert-butyl-1,2-benzoquinone and μ-bpym = 2,2′-bipyrimidine). The synthesis is performed by reacting Co₂(CO)₈ and μ-bpym in the presence of the ligand 3,5-dbbq in a mixed solvent under inert atmosphere. The magnetic behavior clearly shows the presence of electron transfer from the catecholate ligand to the cobalt center, producing valence tautomers of [Co^II(SQ)₂] with a transition temperature (T_1/2) of 215 K. Photomagnetic studies, performed via both SQUID magnetometry and X-band electron paramagnetic resonance, show the clear presence of photoinduced valence tautomerism, at temperatures considerably higher than previous systems. A metastable charge distribution is observed, strengthening previous investigations on the character of mixed valence ligands. Entropy-driven valence tautomeric interconversion is observed, and drives the transition to the most stable charge distribution. The complex has the ability to coordinate and can be used as a photoswitchable building block, with the photomagnetic characterisation evidencing a metastable state lifetime of the photo-induced valence tautomeric process of ca. 2.9 × 10⁴ s below 20 K. The observed yields are higher than ones in similar systems, showing that tiny changes in the molecular structures may have a huge impact.