X-ray structure of 3-diphenylmethylene-2-(2,4,6-tri-t-butylphenyl)thiaphosphirane 2-sulfide: The first thiaphosphirane with exo-methylene

The title compound was prepared by sulfurization of a 1-phosphaallene and its x-ray structure analysis showed the following notable features of the thiaphosphirane ring: P-S = 2.101(2), P-C = 1.770(5) and S-C = 1.767(5) Å (remarkably short), and ∠SPC = 53.5(2), ∠PSC = 53.6(2) and ∠PCS = 72.9(2)°.     

Chemistry of Several Sterically Bulky Molecules with P=P,P=C,and C≡P Bond

Several sterically protected, low-coordinate organophosphorus compounds with P=P, P=C, and C≡P bond are described in this study. Molecules such as diphosphenes, phosphaalkenes, 1-phosphaallenes, 1,3-diphosphaallenes, 3,4-diphosphinidenecyclobutenes, and phosphaalkynes are stabilized with an extremely bulky 2,4,6-tri-t-butylphenyl (Mes*) group. The synthesis, structures, physical, and chemical properties of these molecules are discussed, together with some successful applications in catalytic organic reactions.     

Synthesis,Structure, and Radical Anion of the First Stable p‐Phosphaquinone

Significant localization of the unpaired electron on the phosphorus atom of phosphasemiquinone radical anion 1 was revealed by EPR spectroscopy. This species was generated by reduction of 1 , the first stable p‐phosphaquinone. Employment of the 3,5‐di‐tert‐butyl‐4‐oxocyclohexa‐2,5‐dien‐1‐ylidene moiety was essential for the synthesis as well as the effective kinetic protection of 1 .     

X-ray Structure of a Pentacarbonyltungsten Complex of 1-Phosphaallene

The structure of a tungstenpentacarbonyl complex of 3, 3-dipheny1-1-(2,4,6-tri-t-butylpheny1)-1-phosphaallene has been determined by X-ray analysis.     

Reaction of dichlorocarbene with 1-(2,4,6-tri-t-butylphenyl)-1-phosphaallenes

1-(2,4,6-Tri-t-butylphenyl)-1-phosphaallene reacted with dichlorocarbene to give 2-dichloromethylene-1-(2,4,6-tri-t-butylphenyl)-1-phosphirane. The structure was confirmed by X-ray crystal structure analysis. A similar isomerization product was obtained in the reaction of dichlorocarbene with 3-phenyl-1-(2,4,6-tri-t-butylphenyl)-1-phosphaallene.     

Reactions of a sterically protected 2,3‐dichloro‐1,4‐diphospha‐1,3‐butadiene with some alkyl and hydrido lithium reagents

The reactions of 2,3‐dichloro‐1,4‐diphospha‐1,3‐butadiene, which is sterically protected with the 2,4,6‐tri‐t‐butylphenyl group, with some nucleophiles, including alkyllithium reagents and lithium aluminum hydrides, afforded 1,2‐diphosphinoacetylenes or 3‐phosphino‐1‐phosphaallenes. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:171–176, 2000     

Synthesis and Structure of Sterically Crowded Triarylphosphine Bearing 4-Bromo-2,6-Bis(4-tert-Butylphenyl)Phenyl Group

Abstract

A novel sterically crowded triarylphosphine bearing a 2,6-diaryl-4-bromophenyl group, [4-bromo-2,6-bis(4-tert-butylphenyl)phenyl]bis(2,4,6-triisopropylphenyl)phosphine (1), was synthesized. The X-ray crystallography revealed that the bond angles and lengths around the phosphorus atom (110.9°, 1.846 Å) are comparable to those of tris(2,4,6-triisopropylphenyl)phosphine and its derivatives. Triarylphosphine 1 is reversibly oxidized to the radical cation at the potential close to that of the typical sterically crowded (bromoaryl)phosphine, (4-bromo-2,6-diisopropylphenyl)bis(2,4,6-triisopropylphenyl)phosphine, and exhibits the UV absorption at long wavelength (λ_max 332 nm) characteristic of the sterically crowded triarylphosphines. Thus, triarylphosphine 1 can be regarded to be a promising candidate for the key synthetic intermediate or building block to the functional molecules bearing sterically crowded triarylphosphine moieties.