The inherent atomic level structural control of synthetic chemistry enables the creation of qubits, the base units of a quantum information science system, designed for a target application. For quantum sensing applications, enabling optical read-out of spin in tunable molecular systems, akin to defect-based systems, would be transformative. This approach would bring together molecular tunability with optical read-out technology. In theory, nickel ions in octahedral symmetry meet all the criteria for optical readout of spin. Yet, to the best of our knowledge, there are no pulse EPR studies on Ni 2+ molecules. We identified two compounds featuring highly symmetric Ni 2+ centers, thereby engendering weak zero-field splitting to enable EPR addressability: [Ni(phen) 3 ](BF 4 ) 2 (1) and [Ni(pyr 3 ) 2 ](BF 4 ) 2 (2) (phen = 1,10-phenanthroline; pyr 3 = tris-2-pyridyl-methane). Crucially, these complexes feature the requisite strong field ligands to enable emission for optical addressability. We extracted axial zero-field splitting parameters of D = +0.9 cm −1 and +2.7 cm −1 for 1 and 2, respectively, enabling pulse EPR measurements. Both compounds produce emission at λ max = 938−944 nm. The aggregate of these results expands the catalogue of qubit materials to Ni 2+ -based compounds and offers a future pathway for optical readout of these molecules.
Double deprotonation of bis(2-mercapto-4-methylphenyl)amine ([SNS]H) followed by addition to NiCl(PR) in air-free conditions afforded [SN(H)S]Ni(PR) (1a, R = Cy; 1b, R = Ph) complexes, characterized as diamagnetic, square-planar nickel(II) complexes. When the same reaction was conducted with 3 equiv of KH, the diamagnetic anions K{[SNS]Ni(PR)} were obtained (K[2a], R = Cy; K[2b], R = Ph). In the presence of air, the reaction proceeds with a concomitant one-electron oxidation. When R = Cy, a square-planar, S = / complex, [SNS]Ni(PCy) (3a), was isolated. When R = Ph, the bimetallic complex {[SNS]Ni(PPh)} ({3b}) was obtained. This bimetallic species is diamagnetic; however, in solution it dissociates to give S = / monomers analogous to 3a. Complexes 1-3 represent a hydrogen-atom-transfer series. The bond dissociation free energies (BDFEs) for 1a and 1b were calculated to be 63.9 ± 0.1 and 62.4 ± 0.2 kcal mol, respectively, using the corresponding p K and E°' values. Consistent with these BDFE values, TEMPO reacted with 1a and 1b, resulting in the abstraction of a hydrogen atom to afford 3a and 3b, respectively.
The second quantum revolution harnesses exquisite quantum control for a slate of diverse applications including sensing, communication, and computation. Of the many candidates for building quantum systems, molecules offer both...
A new multimetallic construct has been developed utilizing a redox-active metalloligand. The molybdenum complex, Mo[SNS] 2 {1; [SNS]H 3 = bis(2-mercapto-p-tolyl)amine}, has been shown to coordinate to Ni(dppe) {dppe = 1,2bis(diphenylphosphanyl)ethane} through two cis thiolate donors to generate heterobimetallic Mo[SNS] 2 Ni(dppe) (2) and heterotrimetallic Mo[SNS] 2 {Ni(dppe)} 2 (3). X-ray diffraction studies confirm the presence of formal metal-metal bonds between [a] 5574 electron distribution. Given the evidence for a direct communication pathway between the two nickel centers in neutral 3, it is surprising that 3 + shows localized behavior. Current efforts are aimed at understanding the communication pathways resulting in this non-coupled mixed-valent system.
Metrics & MoreArticle Recommendations * sı Supporting Information ABSTRACT: "Open-framework chalcogenides" are an important class of materials that combine porosity with semiconductor behavior, and yet fundamental aspects of their conductivity remain unexplored. Here, we report a combined experimental−computational approach to the iconic subclass of materials TMA 2 MGe 4 Q 10 (TMA = tetramethyl ammonium; M = Mn, Fe, Co, Ni, Zn; Q = S, Se). Direct current (DC) conductivity measurements and density functional theory (DFT) modeling reveal that metal ion and chalcogenide identities dominate key properties of the band structures, while impedance spectroscopy reveals purely electronic band-type transport in the Fe frameworks and redox-type mixed ion−electron conductivity in the others. Redox chemistry and computation suggest that the unique conductivity of Fe arises from its propensity toward Fe 2+ /Fe 3+ mixed valency as a source of ptype doping and from its highly covalent bonds that ensure high carrier mobilities. Taken together, these results demonstrate openframework chalcogenides as a well-defined platform for understanding porous semiconductors and for achieving highly tunable electronic performance.
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