[ A ([18]crown‐6)] 2 [Pt(CO) 3 ] ⋅ 10 NH 3 ( A =K, Rb) – A crystal structure containing the long postulated [Pt(CO) 3 ] 2−

The compound [A([18]crown-6]2[Pt(CO)3] ⋅ 10 NH3 (A=K, Rb, [18]crown- 6=1,4,7,10,13,16-Hexaoxacyclooctadecane) containing the anion [Pt(CO)3]2− was the unexpected result of a reaction between K6Rb6Ge17, Pt(CO)2(PPh3)2, [18]crown-6 and [2.2.2]-crypt. This compound represents the first example of a mononuclear carbonyl platinate and expands the list of known group 10 carbonyl metallates. The central anion has a trigonal planar shape with an approximate D3h symmetry. Theoretical investigations confirm the trigonal planar structure of the carbonylate and give insight into the electronic structure. The calculations reveal a strong charge density at the central platinum atom, while the HOMO shows a dispersion of the residual electrons under and over the carbonyl plane