Abstract
The compound crystallized in a monoclinic system, and was characterized thus: P21/n; a = 8.821(5)Å, b = 14.971(5)Å, c = 14.473(5)Å, β = 101.306(5)°, Z = 4, V = 1874.20(24)Å3. The crystal structure was solved by direct methods and refined by full-matrix least-squares on F2 to final values of R1 = 0.0528 and wR2 = 0.1574. An acyl-group of the dimethylacetylene dicarboxylate ligand underwent a 1,2-acyl shift, while forming a vinylidene dianion, which newly bridged to the cis-dicyclopentadienyldiiron-group by the (μ,η1:η1)-bond fashion with atomic distances of Fe1-Fe2 2.5028(15)Å, C1-C2 1.342(4)Å, and Fe1-C1 1.917(3)Å, Fe2-C1 1.901(3)Å, respectively.
