A fourth polymorph in the family of BEDT‐TTF salts with thiocyanatocuprate(I) anions: (BEDT‐TTF) 4 Cu 3 (NCS) 5

A new crystallographic modification was found in the family of BEDT‐TTF salts containing thiocyanatocuprate(I) anions. The cation radical salt crystallizes in the P ${\bar {1}}$ space group with a  = 8.2720(9) Å, b  = 19.099(2) Å, c  = 43.758(5) Å, α  = 81.088(4)°, β  = 87.253(4)°, γ  = 83.790(4)°, V  = 6786.2(13) Å 3 at 150 K. The BEDT‐TTF radical cations pack in an α‐type motif, but every four columns, there is a slip in the layer. Where this slip occurs, the stacks are coupled in a β″ manner. The material exhibits semiconductive behavior with an activation energy of 0.13 eV above 250 K and 0.22 eV below.Packing motif of the (BEDT‐TTF) 4 Cu 3 (NCS) 5 structure.