112596-25-5Relevant academic research and scientific papers
Lewis base properties of 1λ5-phospha-3,5-dithia-2,4,6-triazines: Crystal and molecular structures of Ph2PS2N3Me+CF3SO 3- and trans-(Ph2PS2N3)2SnCl4 and the electronic structure of H2PS2N3H+
Chivers, Tristram,Liblong, Stephen W.,Richardson, John F.,Ziegler, Tom
, p. 860 - 867 (2008/10/08)
The behavior of Ph2PS2N3 toward Lewis and Br?nsted acids has been investigated, and the following adducts have been isolated: Ph2PS2N3H+BF4 -, Ph2PS2N3H+CF3SO 3, Ph2PS2N3Me+CF3SO 3-, Ph2PS2N3·BCl3, and (Ph2PS2N3)nSnCl4 (n = 1, 2). The progress of the reaction of Ph2PS2N3 with tetrafluoroboric acid was followed by 31P NMR and UV-visible spectroscopies. The adducts exhibit strong visible absorption bands at 410-430 nm. The crystal and molecular structures of Ph2PS2N3Me+CF3SO 3- (5) and trans-(Ph2PS2N3)2SnCl4 (6) have been determined by X-ray crystallography. The crystals of 5 are monoclinic and belong to the space group P21/a, with a = 11.857 (3) A?, b = 13.708 (2) A?, c = 12.417 (3) A?, β = 111.410(11)°, V = 1879.0(7) A?3, and Z = 4. The final R and Rw values were 0.050 and 0.054, respectively. The crystals of 6 are monoclinic and belong to the space group P21/n, with a = 9.238 (1) A?, b = 10.586 (1) A?, c = 21.752 (4) A?, β = 95.320 (8)°, V = 2118.1 (5) A?3, and Z = 2. The final R and Rw values were 0.037 and 0.042, respectively. In both adducts, coordination occurs at a nitrogen atom adjacent to the phosphorus atom of the PS2N3 ring and the coordinated nitrogen atom is lifted 0.78 and 0.71 A? for 5 and 6, respectively, out of the plane formed by the remaining five atoms (SNSNP) of the heterocyclic ring. The P-N bond distances of 1.65-1.67 A? are slightly longer in the adducts compared to those of the parent ring system (d(P-N) = 1.62 A?), but coordination to nitrogen does not cause a notable difference in the lengths of the two P-N bonds in either 5 or 6. There are pronounced inequalities in the S-N bond lengths of the NSNSN unit in the adducts. The S-N bond lengths involving the coordinated nitrogen are 1.71 A?, the adjacent S-N bond distances are 1.63-1.64 A?, and the other two S-N bonds have values in the range 1.55-1.56 A?. The geometry around the tin atom in 6 is approximately octahedral with the two heterocyclic rings occupying trans positions. Ab initio Hartree-Fock-Slater SCF calculations of the electronic and electrostatic components of the protonation energies for the model protonated species H2PS2N3H+ show that the preference for protonation at the nitrogen atom adjacent to phosphorus can be attributed entirely to the electrostatic energy contribution. The conformational changes and hypsochromic shift that occur upon adduct formation are discussed in the context of the calculated electronic structures of the model system H2PS2N3 by using the experimental geometries for Ph2PS2N3 and its methylated derivative.
