Structural investigations of phosphorus–nitrogen compounds. 2. The structures of N₃P₃(NH₂)₂Cl₄, N₃P₃(NPPh₃)(NH₂)Cl₄ and N₃P₃(NPPh₃)Cl₅ and a comparison with other phosphazenylphosphazenes. The relationship of conformation in the solid state to conformation in solution

Abstract

The crystal structures of 2,2-diamino-4,4,6,6-tetrachlorocyclotriphosphazatriene, N3P3(NH2)2C14 (1), and of 2-amino-2-triphenylphosphazenyl-4,4,6,6-tetrachlorocyclotriphosphazatriene, N3P3(NPPh3)-(NH2)C14 (2), have been determined and that of 2-triphenylphosphazenyl-2,4,4,6,6-pentachlorocyclotriphosphaz~:riene, N3P3(NPPh3)C15 (3), has been redeterminc,l by X-ray analysis. [Crystal data: For compound (1) the presence of geminal NH2 groups is established. Compound (2) is the first triphenylphosphazenyl derivative with a type III conformation, and compound (3) has a type I conformation. Structures are compared with those of related compounds. The relationship between conformation in the solid state as determined by dihedreal angles of the phosphazenyl substituent relative to the ring and the preferred conformations in solution as measured by 4j(pp) spin-spin coupling constants is discussed.

Syntheses, Molecular Structures, and Complex Formation of Geminal Di(2-pyridylmethylamino)-substituted Cyclotriphosphazenes

“…The former are attached to the ring nitrogen atoms by one extraordinary short bond (P2±N1 1.559(3), P3±N3 1.549(3) A Ê ) and one the length of which lies in the typical range for phosphazenes (P2±N2 1.588(3), P3±N2 1.584(3) A Ê ). The endocyclic angles of ∼120°are similar to those found in N 3 P 3 (NH 2 ) 2 Cl 4 [25]. The atomic distances around P1 are significantly longer.…”

Structural investigations of phosphorus–nitrogen compounds. 7. Relationships between physical properties, electron densities, reaction mechanisms and hydrogen-bonding motifs of N3P3Cl(6 − n)(NHBu t ) n derivatives

“…( lone-pair of electrons on the N atom towards the P atom. This bond shortening might have been even greater were it not for the conformation of the NHBu t substituents, one of which is in almost a complete Type II conformation, while the other is between Type I and III [an explanation of these conformational types is given by Fincham et al (1986)]. The backdonation is also demonstrated by the sum of the bond angles around the exocyclic N atoms of 358.8 (2) , showing their trigonal planar character.…”

Phosphorus–nitrogen compounds. Part 54. The reactions of geminal N3P3(NH2)2Cl4and of N3P3(NH2)Cl5with alkoxide ions in alcohols. The geminal P(NH2)2to non-geminal P(NH2)(OR) rearrangement. The crystal structures of trans-N3P3(NH2)2(OPrn)4, cis-N3P3(NH2)2(OMe)4Fincham1, Parkes2, Shaw3 et al. 1988J. Chem. Soc., Dalton Trans.21020View full textAdd to dashboardCite

“…In the present system this is obscured by hydrogen-bonding effects, which as we have shown elsewhere have profound effects on bond lengths and angles. 29 In the present structures we note that NH, substituents forming two hydrogen bonds have somewhat shorter P-N bonds than those which form only one and this effect appears to be more pronounced than the differences between geminal and non-geminal amino alkoxy structures. It has been shown e l ~e w h e r e , ~' , ~~ that in general, bondangle changes provide a more reliable guide than bond-length changes relating to electron donor-acceptor properties.…”