Crystal and molecular structure of trimeric phosphonitrilic isothiocyanate

Abstract

The crystal structure of trimeric phosphonitrilic isothiocyanate, I\T3Ps( NCS)6, has been determined by three-dimensional single-crystal %-ray studies. The compound crystallizes in the triclinic space group P i with a = 11.79 (3), b = 8.02 ( 2 ) , c = 10.31 (1) A, a = 96" 0' (30'), P = 99" 4' (30'), -/ = 97" 28' (33'1, and two molecules per unit cell. The calculated density is 1.70 (2) g c m P ; the experimental density is 1.62 ( 8 ) g ~m -~. The structure was solved from 1246 independent nonzero reflections collected on film by the Weissenberg technique and refined to a conventional R factor of 0.12. The nitrogen atoms of two isothiocyanate groups are bonded t o each phosphorus atom in the six-membered phosphorus-nitrogen ring.Five of the atoms of the phosphonitrilic ri;g are planar, with the sixth atom, a nitrogen, 0.15 A out of the plane. The average P-N bond length ia the ring is 1.58 A with a root-mean-square deviation of 0.05 A; the average P-N (exocyclic) bond length is 1.63 f 0.01 A. IntroductionTimeric phosphonitrilic isothiocyanate was first prepared by Audrieth and c o~o r k e r s .~~~ The isothiocyanate structure as opposed to the thiocyanate structure was assigned on the basis of the infrared s p e~t r u m .~ Stahlberg and Steger6 made a detailed study of the Raman spectrum of this compound in solution and also concluded that the structural unit in this compound is the isothiocyanate. They interpreted the spectrum in terms of D a h molecular symmetry.Crystal and molecular structures have been reported for several other trimeric compounds, including the f l~o r i d e ,~ chloride,8, and bromide, lo but no pseudohalide structure has been determined. This paper reports the results of a three-dimensional X-ray analysis on the structure of trimeric phosphonitrilic isothiocyanate.

Crystal and molecular structure of hexamethylcyclotriphosphazene, (NPMe2)3

“…The X-ray crystallographic analysis of (NPMe,), has been p r o m p t e d b y the recent structure determinations of the methylphosphazenes (NPMe,),-, (2)(3)(4)(5) i n addition to t h e previously k n o w n structure o f (NPMe,), (6). The structure o f (NPMe,), is also of interest in relation to those (22), NMe, (23), NCS (24), and 1/2[2,2'-0C6H4C6H40] (25).…”

The Crystal and Molecular Structure of Tetrameric Phosphonitrilic Isothiocyanate

“…This difference is significant, but was also noticed in the structure of trimeric phosphonitrilic isothiocyanate (18). Hazel1 (19) has suggested that there is a relationship between the MRC angle and the N-C and C-S bond lengths.…”

Synthesis of polyphosphazenes with isothiocyanato, thiourethane, and thiourea side groups

“…A solution of the sodium salt of 2-(2-methoxyethoxy)ethanol was prepared from sodium hydride (2.70 g of a 60% dispersion in mineral oil, 0.0675 mol) and 2-(2methoxyethoxy) ethanol (8.11 g, 0.0676 mol) and was added to the polymer solution dropwise. The reaction mixture was stirred for 3 h at 25 °C to yield 21. The 31P NMR analysis indicated resonances at = -9 ppm for P(OCH2CH2OCH2CH2OCH3)2 units and at = -13 ppm for P(OCH2CH2OCH2CH2OCH3)Cl units.…”