Das Isosterenpaar SiO/PN, I. Zur Isosterie von Perchlorcyclosiloxanen und Perchlorcyclophosphazenen. Schwingungsspektren und Röntgenstrukturanalyse von (Cl2SiO)3 und (Cl2SiO)4 / The SiO/PN Isoelectronic Pair, I. Perchlorocyclosiloxanes and Perchlorocyclophosphazenes. Vibrational Spectra and X-Ray Structure Analysis of (Cl2SiO)3 and (Cl2SiO)4

Abstract

Hexachlorocyclotrisiloxane (2) and octachlorocyclotetrasiloxane (4) were prepared by reaction of SiCl4 with O2 at 955 °C. Their mass spectra are compared with those of the isoelectronic cyclophosphazenes. The vibrational spectra of 2 and 4 are very similar and closely related to that of (PNCl2)3, but clearly different from that of the puckered (PNCl2)4 molecule. The X-ray examination of 2 and 4 reveals planarity of the (SiO)n, n = 3 and 4 ring systems, with d(Si—O) on average 1.619(4) and 1.584(3) A, respectively.