Theoretical study on the singlet potential energy surface of CHOP system

Quantum Chemical Calculations on CHOP Derivatives—Spanning the Chemical Space of Phosphinidenes, Phosphaketenes, Oxaphosphirenes, and COP− Isomers

“…120°), strongly suggests the cyclic nature of 1a , although with a certainly elongated endocyclic P–O bond (Table 1) for which no bond critical point (BCP) was found. Moreover, the “acyclic” structure “ 3 ” reported by Fu and coworkers [9] turns out to be erroneously drawn because, according to their data, the P–C–O angle (84.35°) is even more acute than the one reported herein for 1a and, therefore, unambiguously corresponds to an oxaphosphirene species. The P–O bond in 1a is by far the weakest (most flexible) bond according to its lowest relaxed force constant ( k 0 = 0.869 mdyn/Å), compared to the P–C (4.527 mdyn/Å) and C–O (5.510 mdyn/Å) bonds, in agreement with the reported compliance constants computed at the CCSD(T)(fc)/cc-pVTZ level [22].…”

“…With this aim, the PES of the parent oxaphosphirene ring system 1a was thoroughly explored and allowed the location of ten closed-shell molecular CHOP species, together with a fragmentation pathway (Scheme 2). Only significant differences with a previous report computed at the rather similar (see the Computational Details) QCISD(T)/6-311++G(3df,2p)//MP2/6-311++G(d,p) level [9] deserve comments. Another previous report described the geometry and relative energies of five of the closed-shell minima at the more modest B3LYP/6-311G** level [8].…”

“…Somewhat similar is the situation for strained ring systems containing phosphorus for which phosphiranes ( IV ) and 1 H -phosphirenes ( V ) [5] may serve as good cases in point. An existing synthetic challenge is represented by oxaphosphiranes ( VI ) [6,7], only experimentally described as a ligand in transition metal complexes, being valuable due to a high potential in polymer chemistry, and oxaphosphirenes ( VII ) [8,9] (a 3-phosphinyl-1 H -oxaphosphirene was computed as one of the possible CHOP isomers [10]) for which not even a (failed) attempt exists in the literature; the latter may stem from a (discouraging) degree of antiaromaticity [11]. The first stable derivative of a phosphaketene, possessing the general formula RP=C=O, was reported by Appel (R = Mes* = 2,4,6-tri- tert -butylphenyl) [12,13], and which remained the only derivative for a long time.…”

HPCO—A Phosphorus‐Containing Analogue of Isocyanic Acid

“…[16] Numerous theoretical studies have focused on the different isomers of the HPCO system, predicting HPCO to be 23 kcal mol À1 more stable than HOCP,w ith an activation barrier for interconversion of 70 kcal mol À1 . [17][18][19][20][21][22] These computational studies have stimulated further research, indicating that HPCO might be stable in interstellar space.All successful experimental HPCO studies thus far have tried to mimic interstellar conditions,such as low gas-phase concentration of HPCO or the use of noble gas matrices.T hus,t here are two studies of the generation of HPCO by gas discharges of highly dilute PH 3 /CO mixtures (in He or Ar), which allowed the recording of infrared [23] and microwave spectra of HPCO. [24,25] These studies have corroborated the presence of HPCO and not the isomeric HOCP.M ore recently,H PCO has been proposed as an intermediate in the formation of phosphinecarboxamides and phosphinidene-carbene adducts in the reaction of PCO À with ammonium and imidazolium salts, respectively.…”

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].…”