869223-49-4Relevant academic research and scientific papers
Structure and magnetic properties of (meso-tetraphenylporphinato) manganese(III) bis(dithiolato)nickelates
Dawe, Louise N.,Miglioi, Jesse,Turnbow, Laura,Taliaferro, Michelle L.,Shum, William W.,Bagnato, Joshua D.,Zakharov, Lev N.,Rheingold, Arnold L.,Arif, Atta M.,Fourmigue, Marc,Miller, Joel S.
, p. 7530 - 7539 (2005)
The crystal structures of [MnTPP]{Ni[S2C2H(CN)] 2} [MnTPP = (meso-tetraphenylporphinato)manganese(III)] and [MnTPP]{Ni[S2C2(CN)2]2} have been determined. These salts possess trans-μ-coordination of S = 1/2 {Ni[S 2C2H(CN)]2}?- and {Ni[S 2C2(CN)2]2}?- to Mn(III) and form parallel 1-D coordination polymer chains exhibiting νCN at 2210 and 2200 and 2220 and 2212 cm-1, respectively. The bis(dithiolato) monoanions are planar and bridge two cations with MnN distances of 2.339(16), and 2.394(3) A, respectively, which are comparable to related MnN distances observed for [MnTPP][TCNE]?x(solvates). In addition, [MnTP′P]{Ni[S2C2(CN)2] 2} {H2TP′P = mesotetrakis[3,5-di-tert-butyl-4- hydroxyphenyl)porphyrin] and [MnTP′P(OH2)]{Ni[S 2C2(CN)2]2} were prepared. The latter forms isolated paramagnetic ions. The room-temperature values of χ T for 1-D [MnTPP]{Ni[S2C2H(CN)]2}, [MnTPP]-{Ni[S2C2(CN)2]2}, and [MnTP′P]{Ni[S2C2(CN)2]2} are 2.55, 3.28, and 2.86 emu K/mol, respectively. Susceptibility (χ) measurements between 2 and 300 K reveal weak antiferromagnetic interactions with Θ = -5.9 and -0.2 K for [MnTPP]{Ni[S2C2H(CN)] 2} and [MnTPP]{Ni[S2C2(CN)2] 2}, respectively, and stronger antiferromagnetic coupling of -50 K for [MnTP′P]{Ni[S2C2(CN)2]2} from fits of χ(T) to the Curie-Weiss law. The 1-D intrachain coupling, Jintra of [MnTPP]{Ni[S2C2H(CN)]2} and [MnTPP]{Ni[S2C2(CN)2]2} was determined from modeling χT(T) by the Seiden expression (H = -2JS i·Si) with J/kB = -8.00 K (-5.55 cm -1; -0.65 meV) for [MnTPP]{Ni[S2C2H(CN)] 2}, J/kB = -3.00 K (-2.08 cm-1; -0.25 meV) for [MnTP′P]{Ni[S2C2(CN)2]2}, and J/kB = -122 K (-85 cm-1) for [MnTP′P]-{Ni[S 2C2(CN)2]2}. These observed negative Jintra/kB values are indicative of antiferromagnetic coupling. These materials order as ferrimagnets at 5.5,2.3, and 8.0 K, for [MnTPP]{Ni[S2C2H(CN)]2}, [MnTPP]{Ni[S 2C2(CN)2]2}, and [MnTP′P]-{Ni[S2C2(CN)2]2}, respectively, based upon the temperature at which maximum in the 10 Hz χ′(T) data occurs. [MnTP′P]{Ni[S2C 2(CN)2]2} has a coercivity of 17 700 Oe and remanent magnetizations of 7250 emu Oe/mol at 2 K and 17 Oe and 850 emu Oe/mol at 5 K; hence, upon cooling it goes from being a soft magnet to being a very hard magnet.
