Reactivity of Sodium Pentaphospholide Na[cyclo‐P(5)] towards C≡E (E=C, N, P) Triple Bonds

A diglyme solution of Na[cyclo‐P(5)] (1) reacts with alkynes and isolobal nitriles and phosphaalkynes to afford the otherwise elusive (aza)phospholide anions 2 a–c, 4 a,b, and 6. The reaction of Na[cyclo‐P(5)] with alkynes and nitriles was studied by means of DFT methods, which suggested a concerted mechanism for the formation of 2 a and 4 b. The anions 2 a–c, 4 a,b, and 6 coordinate in an η (5)‐fashion towards Fe(II) to give the sandwich (aza)phosphametallocenes 3 a–c, 5 a,b and 7 in moderate to good yields. The new compounds were characterized by means of multinuclear NMR spectroscopy, single‐crystal X‐ray diffraction and cyclic voltammetry.