Synthesis and X-Ray Crystal Structure of [(thf)4Ca{Fe2(CO)6(μ-CO)(μ-PPh2)}2]

The reactions of [(thf)4Ca(PPh2)2] with the iron carbonyls Fe2(CO)9 and Fe3(CO)12 in THF yield mixtures of iron carbonyl-containing phosphanides which transform upon prolonged heating into [(thf)4Ca{Fe2(CO)6(μ-CO)(μ-PPh2)}2] (1) with a chemical shift of δ(31P) = 127.9 ppm. The distorted octahedrally coordinated calcium atom binds to four THF molecules (av. Ca-O 234.0 pm) and the bridging carbonyl ligand of the complex anions {Fe2(CO)6(μ-CO)(μ-PPh2)}-[Ca-O 229.8(4), Fe-Fe 257.9(2) pm].