Structure and Magnetic Properties of (<i>m</i><i>eso</i>-Tetraphenylporphinato)manganese(III) Bis(dithiolato)nickelates

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[S2C2H(CN)]2}•- and {Ni[S2C2(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) Å, 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 = meso-tetrakis[3,5-di-tert-butyl-4-hydroxyphenyl)porphyrin] and [MnTP‘P(OH2)]{Ni[S2C2(CN)2]2} were prepared. The latter forms isolated paramagnetic ions. The room-temperature values of χT 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 = −2JSi·Sj) 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[S2C2(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[S2C2(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[S2C2(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.