RbCo(CO)4 crystallizes in the monoclinic C2/c space group. Rb(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(1) atoms. Co(1) is bonded in a tetrahedral geometry to one C(1), one C(2), one C(3), and one C(4) atom. There are four inequivalent C sites. In the first C site, C(1) is bonded in a linear geometry to one Co(1) and one O(1) atom. In the second C site, C(2) is bonded in a linear geometry to one Co(1) and one O(2) atom. In the third C site, C(3) is bonded in a linear geometry to one Co(1) and one O(3) atom. In the fourth C site, C(4) is bonded in a linear geometry to one Co(1) and one O(4) atom. There are four inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1) and one C(4) atom. In the second O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one C(1) atom. In the third O site, O(2) is bonded in a distorted single-bond geometry to one Rb(1) and one C(2) atom. In the fourth O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1) and one C(3) atom.
RbCo(CO)4 crystallizes in the monoclinic C2/c space group. Rb(1) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(1) atoms. The Rb(1)-O(2) bond length is 2.95 Å. The Rb(1)-O(3) bond length is 2.96 Å. The Rb(1)-O(4) bond length is 3.01 Å. There is one shorter (3.01 Å) and one longer (3.24 Å) Rb(1)-O(1) bond length. Co(1) is bonded in a tetrahedral geometry to one C(1), one C(2), one C(3), and one C(4) atom. The Co(1)-C(1) bond length is 1.73 Å. The Co(1)-C(2) bond length is 1.74 Å. The Co(1)-C(3) bond length is 1.75 Å. The Co(1)-C(4) bond length is 1.74 Å. There are four inequivalent C sites. In the first C site, C(1) is bonded in a linear geometry to one Co(1) and one O(1) atom. The C(1)-O(1) bond length is 1.18 Å. In the second C site, C(2) is bonded in a linear geometry to one Co(1) and one O(2) atom. The C(2)-O(2) bond length is 1.18 Å. In the third C site, C(3) is bonded in a linear geometry to one Co(1) and one O(3) atom. The C(3)-O(3) bond length is 1.17 Å. In the fourth C site, C(4) is bonded in a linear geometry to one Co(1) and one O(4) atom. The C(4)-O(4) bond length is 1.17 Å. There are four inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1) and one C(4) atom. In the second O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Rb(1) and one C(1) atom. In the third O site, O(2) is bonded in a distorted single-bond geometry to one Rb(1) and one C(2) atom. In the fourth O site, O(3) is bonded in a distorted single-bond geometry to one Rb(1) and one C(3) atom.