[BP 2 ] 3⊖ and [BAs 2 ] 3⊖ , Zintl Anions with Propadiene Structure

It is not the composition of the compounds K 3 BX 2 ( 1 : X = P, 2 : X = As) that enforces the propadiene‐like structure on their anions [XBX] 3⊖ which was established by X‐ray structure analyses and vibration spectra. Bond lengths of d B−P = 176.7 and d B−As = 186.8 pm were determined; these correspond to a Pauling bond order of 1.9. The compounds 1 and 2 , the first ternary boron phosphides and arsenides, are accessible at 1000–1100 K from the elements or by use of BP and BAs, respectively.