Exceptionally electron-rich, nearly trigonal-planar tricyanidometalate anions [Fe(CN)₃]⁷⁻ and [Ru(CN)₃]⁷⁻ were stabilized in LiSr₃[Fe(CN)₃] and AE_3.5[M(CN)₃] (AE=Sr, Ba; M=Fe, Ru). They are the first examples of group 8 elements with the oxidation state of −IV. Microcrystalline powders were obtained by a solid-state route, single crystals from alkali metal flux. While LiSr₃[Fe(CN)₃] crystallizes in P6₃/m, the polar space group P6₃ with three-fold cell volume for AE_3.5[M(CN)₃] is confirmed by second harmonic generation. X-ray diffraction, IR and Raman spectroscopy reveal longer C−N distances (124–128 pm) and much lower stretching frequencies (1484–1634 cm⁻¹) than in classical cyanidometalates. Weak C−N bonds in combination with strong M−C π-bonding is a scheme also known for carbonylmetalates. Instead of the formal notation [Fe^−IV(CN⁻)₃]⁷⁻, quantum chemical calculations reveal non-innocent intermediate-valent CN^1.67− ligands and a closed-shell d¹⁰ configuration for Fe, that is, Fe²⁻.