Effects of nonspherical tetraalkylammonium cations on the structure and magnetic properties of non-Prussian blue structured manganese(II) Prussian blue analogues.

摘要

Prussian blue (PB) and its analogues (PBAs) hold a unique place in the world of molecule-based magnets (MBM) as they have been the most studied and are the best understood. Even though extensively studied, PB and PBAs continue to offer new and interesting insights into the world of MBM and the phenomenon called magnetism. The work described here provides the first steps in looking at the effects that nonspherical cations can have on the structure and magnetic properties of PBAs. The magnetic properties of several novel PBAs are presented. In this work, the products formed by reacting a non-spherical tetraalkylammonium cation, e.g., [NMe₃Et]+, [NMe₂Et₂]+, and [NMeEt₃]+, with MnII(OAc)₂ acetate are presented. Seven pure compounds have been isolated at the time of this writing.;The reaction of [NMe₃Et]CN with MnII(OAc)₂ in water yielded a lime-green compound of [NMe₃Et]₃Mn₅(CN)₁₃ composition that is a three-dimensional PBA incorporating a pentacyanomaganate ion. Reaction of [NMe₃Et]CN with MnII(OAc)₂ in methanol yielded the product of nominal [NMe₃Et]₅Mn₉(CN)₂₃ composition which exhibits an unprecedented gold color. A second reaction in methanol yielded a product with a molecular formula of nominal [NMe₃Et]₂Mn₃(CN)₈ composition. This compound exhibits a spin-frustrated or spin-glass behavior.;The reaction of [NMe₂Et₂]CN with MnII(OAc)₂ in water yielded a material of [NMe₂Et₂]₃Mn₈(CN)₁₉ composition. Running the reaction in methanol yielded.;[NMe₂Et₂]Mn₃(CN)₇. Analysis of the magnetic data indicates that this compound has all three MnII sites in the high-spin configuration.;The reaction of [NMeEt₃]CN with MnII(OAc)₂ in methanol yields another all high-spin compound with [NMeEt₃]₂Mn₂(CN)₆ composition. This reaction, when carried out in an aqueous solution, yielded the product [NMeEt₃]₃Mn₈(CN)₁₉.