Reactions of iron, carbon, and silicon in Pr/Ni eutectic (which has a melting point of 465 °C) have produced three carbometalate intermetallics with structures featuring trigonal planar FeC3 species. The ternary phase Pr12Fe5C15 has the hexagonal Y12Re5C15 structure type; it features FeC3 and Fe3C9 units surrounded by praseodymium cations. The Fe3C9 cluster can be viewed as a cyclic trimer of corner-sharing FeC3 species. The cubic phase Pr21Fe8Si7C12 (an analog of the La21Fe8Sn7C12 type) features Fe4C6 clusters which have previously been described as Fe4 tetrahedra edge-capped by carbon, but are also recognizable as tetramers of corner-sharing FeC3 units. The tetragonal phase Pr62Fe21Si16C32 (with a new structure type) has a 3-D network of corner-sharing FeC3 units, creating a zeolite-like framework that surrounds praseodymium and silicon sites. The quaternary Pr/Fe/Si/C phases are often seen as competing products, likely due to the similarities of their structures and stoichiometric ratios; modification of heating profile has proven to be a useful way to isolate each of these compounds. The magnetic properties are determined by the ordering of praseodymium moments.

Structurally related carbometalates grown from Pr/Ni flux

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.