Two polymorphs of [Rh(μ-I)(COD)](2)

The solid-state structure of di-μ-iodido-bis­{[(1,2,5,6-η)-cyclo­octa-1,4-diene]rhodium(I)}, [Rh(2)I(2)(C(8)H(12))(2)] or [Rh(μ-I)(COD)](2), was determined from two crystals with different morphologies, which were found to correspond to two polymorphs containing Rh dimers with significantly different mol­ecular structures. Both polymorphs are monoclinic and the [Rh(μ-I)(COD)](2) mol­ecules in each case possess C(2) v symmetry. However, the core geometry of the butterfly-shaped Rh(2)I(2) core differs substanti­ally. In the C2/c polymorph, the core geometry of [Rh(μ-I)(COD)](2) (B) is bent, with a hinge angle of 96.13 (8)° and a Rh⋯Rh distance of 2.9612 (11) Å. The P2(1)/c polymorph features a more planar [Rh(μ-I)(COD)](2) (P) core geometry, with a hinge angle of 145.69 (9)° and a Rh⋯Rh distance of 3.7646 (5) Å.