Synthesis of cationic complexes [(C4Me4)CoL]+ (L is naphthalene, phenanthrene, and anthracene)

Crystal structure of [(1,2,3,4,11,12-η)-anthracene]tris-(tri-methyl-stann-yl)cobalt(III)

The first reported structure of a cobalt complex containing an η⁶-anthracene ligand is presented. The anthracene ligand is nearly flat and coordinates the metal asymmetrically, such that the ring junction carbon atoms are slightly further from the cobalt center than are the other four.

The asymmetric unit of the title structure, [Co(η⁶-C₁₄H₁₀){Sn(CH₃)₃}₃], contains two independent mol­ecules. Each anthracene ligand is η⁶-coordinating to a Co^III cation and is nearly planar [fold angles of 5.4 (3) and 9.7 (3)°], as would be expected for its behaving almost entirely as a donor to a high-oxidation-state metal center. The slight fold in each anthracene ligand gives rise to slightly longer Co—C bond lengths to the ring junction carbon atoms than to the other four. Each Co^III cation is further coordinated by three Sn(CH₃)₃ ligands, giving each mol­ecule a three-legged piano-stool geometry. In each of the two independent mol­ecules, the trio of SnMe₃ ligands are modeled as disordered over two positions, rotated by approximately 30%, such that the C atoms nearly overlap. In one mol­ecule, the disorder ratio refined to 0.9365 (8):0.0635 (8), while that for the other refined to 0.9686 (8):0.0314 (8). The mol­ecules are well separated, and thus no significant inter­molecular inter­actions are observed. The compound is of inter­est as the first structure report of an η⁶-anthracene cobalt(III) complex.