SCHEDULED MAINTENANCE
Crystal structure of 2,trans-4,cis-6,trans-8-tetrachloro-2,4,6,8-tetrakis-(dimethylamino)cyclotetraphosphazene
Abstract
Crystals of the title compound N4P4Cl4(NMe2)4, m.p. 168 °C, are monoclinic with a= 18.76(1), b= 18.86(1), c= 13.67(1)Å, β= 109.17(1)°, space group P21/c, and Z= 8. Atomic positions have been determined by Patterson and Fourier methods from X-ray diffractometer data and refined by least squares to R 0.066 for 3 300 reflections. The asymmetric unit contains two molecules which have the cis-trans-cis-trans arrangement of NMe2 groups as suggested previously. The overall structure is very similar to that of the corresponding fluoro-derivative, N4P4F4(NMe2)4. Ring P–N distances vary from 1.528 to 1.580 Å(mean 1.556 Å); mean values for other parameters are P–N(amine) 1.625 and P–Cl 2.053 Å, and N–P–N 120.9 and P–N–P 136.3°. The ring conformation, intermediate between the saddle and tub, is that expected on the basis of the substituent arrangement.
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