Crystal structure of K[Zn(CO)].

The crystal structure of K[Zn(CO)], hexa-potassium tetra-carbonato-zincate(II), comprises four unique potassium cations (two located on a general position, and two on the twofold rotation axis of the space group 2/) and a [Zn(CO)] anion. The Zn atom of the latter is located on the twofold rotation axis and is surrounded in a slightly distorted tetra-hedral manner by two pairs of monodentately binding carbonate groups, with Zn-O distances of 1.9554 (18) and 1.9839 (18) Å. Both carbonate groups exhibit a slight deviation from planarity, with the C atom being shifted by 0.008 (2) and 0.006 (3) Å, respectively, from the plane of the three O atoms. The coordination numbers of the potassium cations range from 6 to 8, using a threshold of 3.0 Å for K-O bonding inter-actions being significant. In the crystal structure, [KO] polyhedra and [Zn(CO)] groups share O atoms to build up the framework structure.