Hydrostannylation of phosphaalkenes [1]

Abstract

Hydrostannylation reactions of the phosphaalkenes 9,11, and 21 with the triorganotin hydrides 1 proceed by different routes. Whereas the trior‐ganotin hydrides 1a,b undergo regioselective 1,2‐addition to the P/C double bond of the P‐aminophosphaalkene 9 to furnish the 2‐stannylphosphanes 17a,b, the 1,2‐addition products to the P‐halophosphaalkenes 11 and 21 can only be postulated as the reactive intermediates 20 and 23, respectively. The reactions of 11 with 1a,b proceed with cleavage of the triorganotin halide via the diphosphene 15 to furnish the cyclophosphanes 18 and 19. On the other hand, the hydrostannylation reactions of the phosphaalkene 21 are not selective, and the 1,3‐diphosphetane 22 is isolated as one of the reaction products. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:453–460, 1998

Dimers and Trimers of Diphosphenes: A Wealth of Cyclo‐Phosphanes

“…These values compare well with those of other P 4 ring systems, in which fold angles span a wide range from 173 to 110° 34. 35 This demonstrates the high flexibility of the four‐membered ring system due to a flat energy potential for that kind of deformation.…”

Low‐Temperature Isolation of the Bicyclic Phosphinophosphonium Salt [Mes*2P4Cl][GaCl4]

“…The bicyclic system is folded along the P1P2 and C19C22 axes (angles between least squares planes: P3‐P4‐P1‐P2/P1‐P2‐C22‐C19/C22‐C19‐C20‐C21 72.1°/63.2°). The P 4 ring system is rather flat (fold angle: 159°), but well within typical parameters (110°–173°) 54. 55 P1 sits in a distorted tetrahedral environment, and the other P atoms exhibit trigonal pyramidal coordination.…”

Trimethylsilylated Allyl Complexes of Nickel. The Stabilized Bis(π-allyl)nickel Complex [η3-1,3-(SiMe3)2C3H3]2Ni and Its Mono(π-allyl)NiX (X = Br, I) Derivatives

“…The sole characterization for (MeP) 4 was a singlet in the 31 P NMR spectrum at −67.7 ppm, a value recorded at 160 °C; no 1 H or 13 C NMR data were reported. Although the 31 P chemical shift is reasonable (a variety of cyclotetraphosphanes have 31 P NMR chemical shifts in the range from −50 to −80 ppm , ), it is not definitive for (RP) 4 rings, as evidenced by the considerably more deshielded values displayed by [(C 5 Me 5 )P] 4 (−39.0 ppm) and {[(SiMe 3 ) 2 CH]P} 4 (−14.6 ppm) …”

“…Although the 31 P chemical shift is reasonable (a variety of cyclotetraphosphanes have 31 P NMR chemical shifts in the range from -50 to -80 ppm 58,59 ), it is not definitive for (RP) 4 rings, as evidenced by the considerably more deshielded values displayed by [(C 5 -Me 5 )P] 4 (-39.0 ppm) 60 and {[(SiMe 3 ) 2 CH]P} 4 (-14.6 ppm). 61 The energetics of the transformation of PMe 3 to (MeP) 4 are reasonable, 56 but in order for the latter to be the product of the reaction of 1 with PMe 3 , multiple steps involving demethylation and P-P formation must be involved. Why such a transformation should occur with 1 but has not been reported with the unsubstituted (C 3 H 5 ) 2 Ni may be related to the relatively unencumbered coordination environment of the latter.…”