Chromium complexes with mixed Group 15 elements as ligands. Synthesis and characterisation of the first cyclo-P2As ligand in [CrCp(CO)2(3-P2As)]

Reaction of [{CrCp(CO)2}2(µ-2-P2)] 1 with PCl5 or ECl3 (E = P, As or Sb) led to cyclo-P2E ligand complexes [CrCp(CO)2(3-P3)] 2 and [CrCp(CO)2(3-P2As)] 4. The eliminated [CpCr(CO)2] fragment of 1 is converted into [CrCp(µ-Cl)Cl]2 3. Co-crystals of 4 and 2 were characterised by Total Reflection X-ray Fluorescence Analysis and by single crystal X-ray diffraction analysis, revealing the tetrahedral CrP2As core