Fourier transform microwave spectroscopy of the CH2CP(X̃  2B1) radical

Abstract

The hyperfine resolved rotational spectrum of the CH2CP radical in the X̃ 2B1 ground electronic state has been observed for the first time using a Fourier transform microwave spectrometer in combination with a pulsed discharge nozzle. The radical was produced by discharging a mixture of PH3 and C2H2 diluted in either Ar or Ne. A total of 25 hyperfine components of the 202–101 and 303–202 transitions have been measured which enabled us to precisely determine hyperfine coupling constants for both phosphorus and hydrogen nuclei. Spin densities on the phosphorus and β-carbon atoms, estimated from the hyperfine coupling constants, suggest that the radical forms an allenic structure (CP double bond) that is modified by a phosphoryl structure (CP triple bond), which is consistent with the theoretical estimation obtained previously by an ab initio calculation. The nature of the CP chemical bond in the radical is investigated in comparison with the corresponding nitrogen bearing counterparts.

A Combined Density Functional Theory and Coupled Cluster Method Investigation of the Structural Properties and Stabilities of Radical CH2CP and Its Isomers

“…The unpaired electron occupies the out-of-plane p orbital, agreeing with previous experimental results. 12 The results of stronger carbon-phosphorus double bond and weaker carbon-carbon double bond can be considered to come of electron transfer from a single electron on -C and located electrons on the out-of-plane carbon-phosphorus π bond to the carbon-carbon bond which has lower electron density.…”

“…The experimental results also suggested that the CH 2 CP radical forms an allenic structure rather than a phosphoryl form. To our knowledge, besides the two pioneering experimental investigations 11,12 noticed above, the relative stability or geometrical structures of the various possible isomers of compounds CH 2 CP are not known. Then, a detailed knowledge about the structure, bonding, stability, and isomerization properties of various CH 2 CP isomers is very desirable and helpful for understanding the nature of CH 2 CP system.…”

“…Simultaneously, the molecule proved theoretically to be planar, being similar to its nitrogen analogue CH 2 CN. 13,14 Ozeki and co-workers 12 have observed the hyperfine resolved rotational spectrum of the CH 2 CP radical in the X 2 B 1 ground electronic state using a Fourier transform microwave spectrometer. The experimental results also suggested that the CH 2 CP radical forms an allenic structure rather than a phosphoryl form.…”

“…10 More recently, another species with carbon-phosphorus multiple bond, CH 2 CP, which is the derivative of the methyl radical resulting from substitution of one of the hydrogen atoms by a CP group, is investigated by Ahmad 11 and Ozeki. 12 Ahmad et al 11 experimentally studied the rotational, centrifugal distortion, and spin-rotation coupling constants of CH 2 CP radical by laboratory submillimeter-wave spectroscopy. Simultaneously, the molecule proved theoretically to be planar, being similar to its nitrogen analogue CH 2 CN.…”

Theoretical investigation on the radical-neutral reaction mechanism of CP with CH2CO and the structural nature of several low-lying intermediates

“…Considering of the product distribution of CN with CH 2 CO, we think that some important and interesting carbon-phosphorusbearing molecules, such as HCP [19][20][21]22], HCCP [23][24][25][26][27], HOCP [28][29][30][31][32][33][34], CH 2 CP [35][36][37], and HCCCP [38][39][40], may be possible products in the reactions of carbon monophosphide (CP), the phosphorus analogue of CN, with CH 2 CO. The CP radical is a well-known interstellar molecule [41,42].…”