A Singlet Phosphinidene Stable at Room Temperature Liu Liu, David A. Ruiz, Dominik Munz, Guy Bertrand  Chem  Volume 1, Issue 1, Pages 147-153 (July 2016) DOI: 10.1016/j.chempr.2016.04.001 Copyright © 2016 Elsevier Inc. Terms and Conditions

Chem 2016 1, 147-153DOI: (10.1016/j.chempr.2016.04.001) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 1 Schematic Representation of (Phosphino)phosphinidenes A Considered in This Study, Including A2 and A4, which Have Been Trapped and Isolated, Respectively Chem 2016 1, 147-153DOI: (10.1016/j.chempr.2016.04.001) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 2 Synthesis and Reactivity of phosphaketene 2a (Top) Synthesis of phosphaketene 2a (see also Figures S1–S3), which undergoes CO elimination under UV irradiation, generating transient phosphinidene A2. (Bottom) In the absence of trapping agent, A2 dimerizes to produce 3a (see also Figures S4–S6), whereas in the presence of 1-adamantyl isocyanide, the expected phosphinidene-isonitrile coupling product 4a is obtained (bottom left and right, respectively; see also Figures S7–S9). A molecular view of 3a and 4a in the solid state is shown; H atoms are omitted for clarity (orange, P; blue, N). Chem 2016 1, 147-153DOI: (10.1016/j.chempr.2016.04.001) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 3 Synthesis and Reactivity of Bulky phosphaketene 2b (Top) Synthesis and reactivity of phosphinidene A4 (see also Figures S10–S29). (Bottom left) 31P NMR spectrum of A4 (asterisk denotes unidentified impurity; see also Figure S20). (Bottom right) Molecular view of 4c in the solid state; H atoms and solvent molecules are omitted for clarity (orange, P; blue, N). Chem 2016 1, 147-153DOI: (10.1016/j.chempr.2016.04.001) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 4 Computational Analysis of phosphinidenes A (A and B) Optimized structures of A2 (A) and A4 (B) show the protection of the phosphinidene center by 2,6-bis[(4-tert-butylphenyl)methyl]-4-methylphenyl substituents (Ar**) (orange, P; blue, N). (C) HOMO of A2: in-plane P1-P2 π orbital. (D) HOMO-1 of A2: out-of-plane P1-P2 π orbital. (E) HOMO-8 of A2: P1-P2 σ-bonding orbital. (F) LUMO of A2: P1-P2 π*-antibonding orbital. (G) The four main resonance structures of A2 as predicted by natural resonance theory (NRT). (H) The two resonance structures of NHCs as predicted by NRT at the same level of theory. Chem 2016 1, 147-153DOI: (10.1016/j.chempr.2016.04.001) Copyright © 2016 Elsevier Inc. Terms and Conditions