Zur Chemie und Strukturchemie von Phosphiden und Polyphosphiden, 49 [1]. Bildung und Struktur des Henicosaphosphids [Li(12-Krone-4)2]3P21(THF)2 / Chemistry and Structural Chemistry of Phosphides and Polyphosphides, 49 [1]. Formation and Structure of the Henicosaphosphide [Li(12-Crown-4)2]3P21(THF)2

Abstract

Abstract The reaction of Li3P7(DME)3 with crown ether 12-crown-4 and (CHT)Cr(CO)3 yields a reddish oil, from which red crystals of [Li(12-crown-4)2]3P21(THF)2 (1), red crystals of Li2P16(12-crown-4)x(THF)2 as well as a not yet identified yellow substance separates. From this mixture crystals of 1 could be isolated. [Li(12-crown-4)2]3P21(THF)2 (1) crystallizes in the space group P21/a with a = 3021.1(6) pm, b = 1901.5(4) pm, c = 1603.0(4) pm, β = 95.98(3)° and Z = 4 formula units in the unit cell. The structure is characterized by isolated 1 ∞[P21 3-] trianions and Li(12-crown-4)2 cations. The trianion has approximately the symmetry mm2. The bond distances d(P-P) range from 213.9 pm to 226.8 pm and are differentiated by their function in the skeleton. The bond angles β(P-P-P) are in the range 86.1° to 107.7° and image clearly the influence of the repulsion of the non-bonded electron pairs of the strained anion. The curvature of the trianion is approx. 0.8 nm-1 and is three times larger than the curvature evaluated from structural models.