Triply Bonded Gallium≡Phosphorus Molecules: Theoretical Designs and Characterization

Abstract

The effect of substitution on the potential energy surfaces of triple-bonded RGa≡PR (R = F, OH, H, CH, SiH, SiMe(SitBu), SiiPrDis, Tbt (CH-2,4,6-{CH(SiMe)}), and Ar* (CH-2,6-(CH-2,4,6-i-Pr))) compounds was theoretically examined by using density functional theory (i.e., M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp). The theoretical evidence strongly suggests that all of the triple-bonded RGa≡PR species prefer to select a bent form with an angle (∠Ga-P-R) of about 90°. Moreover, the theoretical observations indicate that only the bulkier substituents, in particular, for the strong donating groups (e.g., SiMe(SitBu) and SiiPrDis) can efficiently stabilize the Ga≡P triple bond. In addition, the bonding analyses (based on the natural bond orbital, the natural resonance theory, and the charge decomposition analysis) reveal that the bonding characters of such triple-bonded RGa≡PR molecules should be regarded as [Formula: see text]. In other words, the Ga≡P triple bond involves one traditional σ bond, one traditional π bond, and one donor-acceptor π bond. Accordingly, the theoretical conclusions strongly suggest that the Ga≡P triple bond in such acetylene analogues (RGa≡PR) should be very weak.

Simulations Suggest Possible Triply Bonded Phosphorus≡E13 Molecules (E13 = B, Al, Ga, In, and Tl)

“…: E13 = PR2) are studied. The respective computational results for RB☰PR [28], RAl☰PR [29], RGa☰PR [30], RIn☰PR [31], and RTl☰PR [32] are…”

“…That is to say, it is easy for the RE13PR species to migrate to the corresponding doubly bonded R2E13 = P: or: E13 = PR2 isomers rather than to the triply bonded RE13 ☰ PR molecules. The theoretical evidence strongly suggests that the experimental detection of RE13☰PR that features small groups is very unlikely so they are not discussed in this section [28][29][30][31][32].…”

“…In order to avoid the London dispersion forces [36], the dispersion-corrected M06-2X/Def2-TZVP level of theory [37] is used to compute geometrical parameters and some properties. The respective results for RB☰PR [28], RAl☰PR [29], RGa☰PR [30], RIn☰PR [31], and RTl☰PR [32] are shown in Tables 1-5. The same level of theory is also used to determine the feasibility of producing triply bonded R'E13 ☰ PR´compounds (Scheme 1 and Tables 1-5).…”

“…Also, molecules that feature a phosphorus double bond have been the subject of many experimental and theoretical studies of structure and reactivity [15][16][17][18][19][20][21][22][23][24][25][26][27]. However, little is known about the molecules that feature a phosphorus triple bond [28][29][30][31][32]. In particular, whether it is possible to anticipate the stability of the R-E13 ☰ phosphorus-R (E13 = B, Al, Ga, In, and Tl) species based on the effects of substituents, since the R-E13 ☰ phosphorus-R systems are isoelectronic to the R-E14 ☰ E14-R (E14 = C, Si, Ge, Sn, and Pb) compound from the valence electron viewpoints.…”

Bonding and Reactivity of Gallium and Aluminium Coordination Complexes

“…Theoretical studies have been performed on the target phosphinidene species in their most basic forms (HAlPH and HGaPH) with idealised M-P double 235 and triple 236 bonding. The HMPH species is 177.7 kJ mol -1 and 188.4 kJ mol -1 higher in energy than tautomers AlPH2 and GaPH2 respectively, significantly higher in comparison with the H3MPH3, H2MPH2, HMPH2 and MP compounds also modelled.…”