Structure and magnetic properties of Ca14MnP11

The compound Ca14MnP11 crystallizes in the Ca14AlSb11 structure type with the tetragonal space group I 4 1 / acd ( Z = 8 ) and lattice parameters of a = 15.3255 ( 7 ) A , c = 20.7565 ( 9 ) at 90 K. The structure consists of MnP49− tetrahedron, P37− trimer, 4 P3− isolated anions and 14 Ca2+ cations. Similar to other compounds of this structure type containing phosphorous, the P37− trimer has a central P atom that is best modeled in the structure as being equally split between two sites. In addition, there is no additional distortion of the manganese-containing tetrahedron compared with the main group analog, Ca14GaP11, suggesting that the Mn oxidation state is Mn2+. Temperature-dependent magnetic susceptibility shows that the compound is paramagnetic over the entire temperature range measured (2–300 K). The data can be fit with a modified Curie–Weiss law and provide an effective magnetic moment of 5.80 (2) B.M. with a Weiss constant of −2.13(2) K and χ 0 = - 9 ( 1 ) × 1 - 5 emu / mol . This moment is significantly higher than those measured for any of the Mn-containing analogs and is consistent with Mn2+. This result will be discussed in light of the electron counting scheme for Mn compounds of the Ca14AlSb11 structure-type.