[1][2][3][4] tetraazaphosphapentalenes (TAPP), [5] tetraazathiapentalenes (TATP), [6][7] tetraazaselenapentalenes (TASP), [8][9] and their derivatives (Scheme 1) are of special interest owing to their unusual electronic structure and chemical behavior which is governed by the striking orientations of the heteroatoms. These heterocyclic systems promise a variety of applications including in organic synthesis, redox chemistry, and in industry, military, and space programs. Some examples of these applications include the derivatization of p-hypervalent heterocyclic TATP, [10][11][12] the synthesis of versatile heterocyclic compounds, [13][14][15] exotic metal carbene chemistry, [16][17][18][19][20] shaped charges for downhole penetrators, [21] and thermally stable high-energy materials. [22][23][24][25][26] Much attention has been focused on the preparation (precursors and methods) and properties of the heterocyclic tetraazapentalenes and their derivatives because their applications depend significantly on their thermal stability, performance, and synthetic practicality.We are interested in the preparation of high-nitrogencontent energetic materials, heterocyclic high-density materials, and green primary explosives for a wide variety of applications through the utilization of tetrazines, [27] tetrazoles, [28] triazines, [29] furazans, [30] triazoles, [31] pyridines, [32] and azetidines.[33] Our interest in heterocyclic tetraazapentalenes was to probe the explosive performance (detonation velocity (V D ) and detonation pressure (P CJ )) of previously synthesized, thermally stable high-energy compounds and to Scheme 1. The structures of tetraazapentalenes (TAPs), tetraazaphosphapentalenes (TAPPs), tetraazathiapentalenes (TATPs), and tetraazaselenapentalenes(TASPs).