Synthesis, Crystal Structure, Magnetic Susceptibility, and Single-Crystal EPR Studies of [DafoneH₂][(CuCl₃H₂O)Cl]

[DafoneH₂][(CuCl₃H₂O)]Cl (dafone = 4,5-diazafluoren-9-one) crystallizes in the monoclinic space group P2₁/c with a = 14.585(2) Å,b = 14.143(7) Å, c = 7.076(6), Å, β = 91.3(2)°, and Z = 4. The crystal contains the unusual chromophore [(CuCl₃H₂O)Cl]^2- showing coordinated water and a semicoordinate Cl^-. Moderately strong antiferromagnetic exchange (J = −72.8 K, with H_ex = −2JŜ₁Ŝ₂) is present. The exchange pathway appears to be via an H-bond involving H₂O and Cl^- of inversion-related molecules. Cl···Cl contacts also exist, but on the basis of geometry, EHMO calculations, and comparison with other systems, they are ruled out as the main exchange pathway. Single-crystal EPR studies (g₁ = 2.069, g₂ = 2.089, g₃ = 2.250) show further weak exchange via H-bonding between the semicoordinate Cl^- and H₂O.