Crystal and Molecular Structure of the Macrocyclic Nickel (II) Complex Ni(C22H22H4): Dibenzo[b,i][5, 7, 12, 14] Tetramethyl [1, 4, 8, 11] Tetraazacyclotetradeca-2, 4, 7, 9, 12, 14-Hexaeneatonickel (II)

The crystal and molecular structure of the four-coordinate complex Ni(C₂₂H₂₂N₄) containing the tetramethyldibenzotetraaza[14] annulene ligand has been determined from three-dimensional X-ray diffraction data. The complex crystallized in the monoclinic space group C_2h⁵-P2₁/n with cell dimensions a=14.7967(10), b=11.2169(6), c=11.4510(6) Å, and β=98.467(5)° with Z=4. The final agreement indices from the least-square refinement of 245 variables with 3111 observations F>3σ(F), are R=0.050, R_w=0.037. The structure has a pronounced saddle-shaped conformation with Ni atom at the saddle point coordinated to four nitrogen atoms. The average Ni-N distance is 1.866(3) Å. The delocalized propane-1,3-diiminato chelate rings and the benzene rings are linked by nominally single C-N bonds.