Methylidenephosphine.

Methylphosphinidene (CH3P) and its rearrangement to phosphaethylene (CH2PH): toward the observation of ground-state triplet CH3P

“…Employing configuration interaction in conjunction with the TZ2P basis set can reduce this error to about 5%. 21 The experimental vibrational frequencies in Table II were obtained in a low-temperature IR spectrum by Pellerin et al 5 They assigned a strong band at 2260 cm-1 to the P-H stretch and tentatively assigned a large band at 850 cm-1 to the C=P stretching frequency. Our TZ2P CISD frequency of 2402 cm-1 for the P-H stretch agrees quite well with the above experimental value and can be compared with the experimental values of 2287.5 cm-1 in (CH3)2PH22 and of 2305 cnr1 in CH3PH223 after reducing the TZ2P CISD frequencies by 5%.…”

Dehydrochlorination of α-Chlorophosphines, a Simple and General Route to Phosphaalkenes

“…The gaseous flow exiting from the VGSR device can also be condensed on a KBr window cooled to 77 K, and the IR spectra of the phosphaalkenes 3a−e can thus be immediately recorded at this temperature in order to minimize the decomposition of the species (see below). From theoretical calculations, the large band at 850 cm -1 , initially attributed to the ν CP stretching frequencies of 3a , must be reassigned to the CH 2 bending frequency which has a very strong intensity. After reexamination of the IR spectra, we attributed the weak band at 1012 cm -1 to the CP stretching frequency.…”

“…They involve either elimination of hexamethyldisiloxane from the stable P-silylated phosphaalkene precursors, the bis(dehydrochlorination) of α-dichlorophosphines, or the base-induced rearrangement of primary ethynylphosphines . While most of the phosphaalkynes are fairly stable in solution at room temperature, − simple phosphaalkenes are highly unstable and undergo self-condensation reactions even at low temperature . This high reactivity probably accounts from the fact that only a few IR and NMR data have been reported to date and that synthetic applications of such compounds remains challenging.…”

“…However, when the leaving group is bonded to the carbon atom, the HX elimination (X = Cl, F) is favored. We 4a,,, and others 7a,13 have used this approach to prepare different phosphaalkenes and phosphaalkynes. In this paper we report a general preparation of primary and secondary α-chlorophosphines and the subsequent formation of simple phosphaalkenes by dehydrochlorination of these compounds either in the gas phase or in the liquid phase.…”

Expanding the Analogy Between P=C and C=C Bonds to Polymer Science

“…In their landmark paper on the first detection of unstable phosphaalkenes, including HP=CH 2 , Hopkinson, Kroto, Nixon, and Simmons reported short half lives (1-2 min) for these species [80]. In later studies on the preparation of HP=CH 2 , it was mentioned that the compound was not stable at 77 K in the solid state and forms a polymer of low solubility [81]. The generation of the transient phosphaalkenes RP= C(H)CH 3 (R=H, Me, Ph) by the base-induced rearrangement of RP(H)CH=CH 2 , reportedly led to a "slow polymerization ... in the absence of chemical trapping agents" (R=H) [82].…”