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(meso-Tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphinato)manganese(III) tetracyanoethenide, (MnTP'P)(TCNE), is a soluble molecule-based magnet made of trans-mu(sub 2)-bound (TCNE).- subunits. With interchain distances, the Curie temperature becomes unusually high. The magnetic susceptibility obeys the Curie-Weiss relation between 115 and 250 K. The (MnTP'P)(TCNE) polymer has short intrachain and long interchain Mn...Mn separations.

Electrochemical, spectroscopic, and X-ray crystallographic studies of organometallic compounds such as (Cp*M(ligand)M'Cp*)n (M, M' = Fe, Co, Ni; n = O, 1+, 2+; ligand = pentalene, indacene), indicate that delocalized strong electron coupling exists between metal sites. The oxidation state does not significantly change the molecular structure of the organometallic compounds and the Cp*M moieties occupy the opposite faces of the fused nu-bridging ring systems.

The existence of electronic triplet species near the fine structure splitting of the tetraethylammonium 2,3,5,6-tetracyano-p-benzoquinonide is revealed in the electron paramagnetic resonance spectroscopy of single crystals of tetraethylammonium. The fine-structure splitting provides information on the spin-spin interaction matrices. The information is expressed as functions of the angle of crystals in three orthogonal planes.

Single-crystal polarized neutron diffraction studies of tetracyanoethenide free radical, (TCNE)(.-), show that the spin density is not completely localized on central sp(2)-carbon nuclei. The spin distribution across the radical reveals that a singly-occupied orbital of this radical is the pi(*) antibonding MO. Diffraction studies and theoretical analysis help understand the ferromagnetic spin-coupling pathway of molecule-based magnets.

The synthesis of tetracyano-1,4-benzoquinone (TCBQ or cyanil), its dihydro form (TCBQH2) and three ionic forms leads to a study of their structures and behavior as electron acceptors. TCBQH2 is prepared by treatment of bromanil with methanolic sodium cyanide. TCBQ is prepared from the disilver salt of TCBQH2. The study reveals TCBQ to be the strongest electron acceptor yet known,so strong that it can deprotonate even such as strong oxidant as 2,3-dichloro-5,6-dicyanohydroquinone. Its protonated salts exhibit unusually short intermolecular hydrogen bonds.

The hydrostatic pressure dependence of the magnetic ordering temperature, Tc(P), for the interpenetrating, diamondoid lattice-structured, weak ferromagnet (= canted antiferromagnet) Li+[TCNE]˙− (TCNE = tetracyanoethylene) reversibly increases from 20.9 to 23.4 K at 9.73 kbar, an increase of 12% with a rate of increase, dTc/dP, of 0.27 K kbar−1. The 5 T magnetization increased by 672% from 186 emu Oe mol−1 at ambient pressure to an average of 1440 emuOe mol−1 upon application of pressure. The remanent magnetization initially increases 30% from 10.8 to 14.0 emuOe mol−1 from ambient to 0.06 kbar, and increases further by 6% to a maximum of 14.8 emuOe mol−1 at 0.56 kbar before declining by 22% to 11.5 emuOe mol−1 at 9.73 kbar. The pressure-dependent coercive field, Hcr(P), initially decreases by 42% from 31.1 Oe at ambient pressure to 18 Oe at 0.06 kbar, then increases to 52 Oe at 9.73 kbar. The canting angle, α, increases by 28% from 0.52° to 0.66° at 0.06 kbar, then decreases by 23% to 0.51° at 9.73 kbar, as well as increases by 2% from 0.536° to 0.548° from 1.8 to 2.5 K, before decreasing by 79% to 0.117° at 19 K. The interlattice interactions are attributed to be the primary exchange mechanism. Thus, α(T) and α(P) have similar dependencies that are attributed to a competition between an increase and a decrease in the intra- and interlayer C⋯N interlattice separations as the temperature and pressure increases. [ABSTRACT FROM AUTHOR]

The facile synthesis, crystal structure, and magnetic properties of a hydroxo-bridged copper(II) cubane complex are reported. It is concluded that the single multistep reaction yields a new copper cubane complex with outer-sphere H-bonding that cause significant variations in the stability ad solid-state bonding parameters of the metal cluster.

The thermal hysteresis of the magnetic susceptibility of the molecule-based solid [Co (super III) Cp2](super +)[Fe(super III)I4](super -) is reported. Bistable materials have great potential in next-generation sensor, switching, and actuator devices.

To identify the genesis of the differing magnetic behaviors for the ferro- (FO) and metamagnetic (MM) polymorphs of [FeCp*2][TCNQ] (Cp* = pentamethylcyclopentadienide; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane) the low temperature (18 ± 1 K) structures of each polymorph were determined from high-resolution synchrotron powder diffraction data. Each polymorph possesses chains of alternating S = 1/2 [FeCp*2]˙+ cations and S = 1/2 [TCNQ]˙+, but with differing relative orientations. These as well as an additional paramagnetic polymorph do not thermally interconvert. In addition, the room and low (<70 ± 10 K) temperature structures of the MM polymorph, MMRT and MMLT, respectively, differ from that previously reported at 167 K (−106 °C) MM structure, and no evidence of either phase transition was previously noted even from the magnetic data. This transition temperature and enthalpy of this phase transition for MMRTMM was determined to be 226.5 ± 0.4 K (−46.7 ± 0.4 °C) and 0.68 ± 0.04 kJ mol−1 upon warming, respectively, from differential calorimetry studies (DSC). All three MM phases are triclinic (P1¯) with the room temperature phase having a doubled unit cell relative to the other two. The lower temperature phase transition involves a small rearrangement of the molecular ions and shift in lattice parameters. These three MM and FO polymorphs have been characterized and form extended 1-D chains with alternating S = 1/2 [FeCp*2]˙+ cations, and S = 1/2 [TCNQ]˙− anions, whereas the fifth, paramagnetic (P) polymorph possesses S = 0 π-[TCNQ]22− dimers. At 18 ± 1 K the intrachain Fe⋯Fe separations are 10.738(2) and 10.439(3) Å for the FO and MMLT polymorphs, respectively. The key structural differences between FO and MMLT at 18 ± 1 K are the 10% shorter interchain N⋯N and the 2.8% shorter intrachain Fe⋯Fe separation present for MMLT. Computational analysis of all nearest-neighbor spin couplings for the 18 K structures of FO and MMLT indicates that the intrachain [FeCp*2]˙+⋯[TCNQ]˙− spin couplings (H = −2Si·Sj) are the strongest (4.95 and 6.5 cm−1 for FO and MMLT, respectively), as previously hypothesized, and are ferromagnetic due to their S = 1/2 spins residing in orthogonal orbitals. The change in relative [TCNQ]˙−⋯[TCNQ]˙− orientations leads to a computed change from the ferromagnetic interaction (0.2 cm−1) for FO to an antiferromagnetic interaction (−0.1 cm−1) for MMLT in accord with its observed antiferromagnetic ground state. Hence, the magnetic ground state cannot be solely described by the dominant magnetic interactions. [ABSTRACT FROM AUTHOR]

Research has been conducted on the trinuclear Co (super)II complexes with bridging dicyanamides and a tris-chelated HAT (HAT= 1,4,5,8,9,12-hexaazatriphenylene). Results indicate the existence of the magnetic exchange pathway in the structure.

The reactions of MnII(O2CCH3)2 with NEt3Me+CN− and NEt2Me2+CN− form (NEt3Me)2MnII5(CN)12 (1) and (NEt2Me2)2MnII5(CN)12 (2), respectively. Structure model‐building and Rietveld refinement of high‐resolution synchrotron powder diffraction data revealed a cubic [a=24.0093 Å (1), 23.8804 Å (2)] 3D extended structural motif with adjacent tetrahedral and octahedral MnII sites in a 3:2 ratio. Each tetrahedral MnII site is surrounded by four low‐spin octahedral MnII sites, and each octahedral MnII site is surrounded by six high‐spin tetrahedral MnII sites; adjacent sites are antiferromagnetically coupled in 3D. Compensation does not occur, and magnetic ordering as a ferrimagnet is observed at Tc=13 K for 2 based on the temperature at which remnant magnetization, Mr(T)→0. The hysteresis has an unusual constricted shape with inflection points around 50 and 1.2 kOe with a 5 K coercivity of 16 Oe and remnant magnetization, Mr, of 2050 emuOe mol−1. The unusual structure and stoichiometry are attributed to the very ionic nature of the high‐spin N‐bonded MnII ion, which enables the maximization of the attractive van der Waals interactions through minimization of void space via a reduced ∠ MnNC. This results in an additional example of the AxMnIIy(CN)x+2y (x=0, y=1; x=1, y=3; x=2, y=1; x=2, y=2; x=2, y=3; x=3, y=5; and x=4, y=1) family of compounds possessing an unprecedented stoichiometry and lattice motif that are cation adaptive structured materials. [ABSTRACT FROM AUTHOR]

Polymer-based V(tetracyanoethylene)x.y(solvent) magnets with low density, low power loss and high resistivity to wear and friction are used in low and static frequency magnetic shielding and inductive processes. The magnets have a high room temperature permeability value of 13 which is essential for all shielding applications.