Synthesis, Crystal Structure, and Properties of MnNCN, the First Carbodiimide of a Magnetic Transition Metal

Synthesis, single-crystal structure determination, and magnetic properties are reported for manganese carbodiimide, MnNCN. The presumably unstable but inert phase adopts the trigonal system (R3̄m) with a = 3.3583(4) Å, c = 14.347(2) Å, V = 140.13(3) Å3, and Z = 3. Divalent manganese is octahedrally coordinated by nitrogen atoms at 2.26 Å, and the NCN2- unit adopts the linear [NCN]2- carbodiimide shape with two CN double bonds of 1.23 Å. MnNCN contains high-spin Mn(II) with five unpaired electrons and behaves like an antiferromagnet with an ordering temperature below 30 K.