Structures of Phosphaethylenes and a 1-Phosphaallene Containing Phosphorus in Lower Coordination State

Abstract

The X-ray analyses of sterically protected Z-2-r-butyldimethylsilyloxy-2-phenylphosphaethylene ( Z-2) and 3.3-diphenyl-1-phosphaallene (3) were carried out and the structures of the parent compounds, HP=CH, and HP=C=CH,. were optimized by ub inirio methods.

Topochemical [2+2] Dimerization of Kinetically Stabilized 1‐Phosphaallenes in the Solid State

“…[13] The resonance structure [HP ϩ C Ϫ ϭCH 2 ] was also suggested although its contribution was found to be negligible. [9,13] These results hence correspond to the reactivity of 5. In contrast, 1 cyclized at positions corresponding to the terminal CϭC bond.…”

“…The bond lengths and angles in the ϪPϭCϭC moiety are nearly identical to those of 1-(2,4,6-tri-tert-butylphenyl)-3,3-diphenyl-1-phosphaallene. [9] Two molecules of 1 are paired in the crystalline state and the hydrogen atom bonded to the C2 atom is in close proximity to the aromatic ring of the other molecule. Indeed, the CHϪπ interaction is assumed to be a noncovalent interaction operating in the crystal structure.…”

ChemInform Abstract: X‐Ray Structure of 3‐Diphenylmethylene‐2‐(2,4,6‐tri‐t‐butylphenyl) thiaphosphirane 2‐Sulfide: The First Thiaphosphirane with exo‐ Methylene.

“…The P-C(1) bond length of the ring (1.770(5) A) is similar to that for 5 (1.795(7 A). slightly longer than that for the 1-phosphaallene 1 (1.327(5) A) [7,141. The benzene ring of the 2,4,6tri-t-butylphenyl group is distorted to an envelope form and atoms C(4)-C(8) are coplanar.…”

“…The starting material, 3,3-diphenyl-1-(2,4,6-tri-t-butylpheny1)-1 -phosphaallene (1) was prepared by either reaction of a lithium silylphosphide with diphenylketene [3] or reaction of a 1-silyl-2-phosphaethenyl-lithium with benzophenone 161 (Scheme 1). The title compound, 3-diphenylmethylene-2-(2,4,6tri-t-butylpheny1)thiaphosphirane 2-sulfide (3) was prepared by sulfurization of 1 by the method previously described by ourselves [7]. When the ,'P nuclear magnetic resonance (NMR) spectrum was taken during the reaction, a peak appeared at tip 79 and indicated the initial formation of the l- Compound 3 is a phosphorus analogue of allene episulfide, which is thermodynamically more stable than its valence isomer, cyclopropanethione [ll] (Scheme 2).…”

“…The ultraviolet spectra were (2) LS( 1 )-P-C( 1 ) 53.5( 2) P-C( 1 ) 1.770(5) LP-C(l )-S( 1) 72.9(2) 1.767(5) LP-S(l )-C(l ) 53.6(2) 1.923 (2) LP-C( 1 )-C(2) 1 51 . 1 (4) S(1 ) -W ) P-S(2) P-C (3) 1.833(5) LS(1 )-C(1 )-C(2) 133.2(4) 1.340 (7) LS(l)-P-C(3) 106.1 (1) 1.476 (7) LC ( 1 ) Equivalent isotropic U is defined as one-third the trace of the orthogonalized Ui, tensor. measured on a Hitachi 340 spectrometer.…”