The Rise of Phosphaethynolate Chemistry in Early Transition Metals, Actinides, and Rare‐Earth Complexes

Abstract

In the last seven years, chemistry of the phosphaethynolater eagent, Na(OCP)(1,4-dioxane) 2.5 ,h as seen a surge in organic and inorganic chemistry-A renaissance to cyanate chemistry in an ew guise. Whereas there have been many reports of main group reactivity with [OCP] À , largely from group 14, in more recent times the use of electropositive metals has garnereds ignificant interest given their ability to disguise in variouso xidation states. Herein, we report and discuss advances in such studies of [OCP] À with early transition metal and f-block metal scaffolds.

The “Hidden” Reductive [2+2+1]‐Cycloaddition Chemistry of 2‐Phosphaethynolate Revealed by Reduction of a Th‐OCP Linkage

“…In the ATR‐IR spectrum of 2 , the antisymmetric stretch of (OCP) − is clearly identified as a strong absorption at 1678 cm −1 , but the symmetric stretch could not be assigned due to the complexity of the fingerprint region (Figure S2). The solid structure of 2 (Figure 1) reveals Th−O, O−C, and C−P distances of 2.334(3), 1.246(5), and 1.544(5) Å, and Th‐O‐C and O‐C‐P angles of 173.1(3) and 178.8(5)°, respectively, suggesting overall [11] the dominance of P≡C‐O − , rather than − P=C=O, resonance forms, as commonly observed when this anion is coordinated to electropositive metal ions [3] . The Th−N amide and Th−N amine distances are unremarkable.…”

“…Furthermore, cycloaddition reactions of (OCP) − under oxidising or neutral conditions have become well established, producing a variety of novel three, four‐, five‐, or six‐membered phosphorus heterocycles [1] . In contrast, the reduction chemistry of (OCP) − is in its infancy, [1, 3] but the clear picture already is that this closed‐shell anion resists reduction, to avoid populating antibonding orbitals, inevitably leading, when reduction can be effected, to spontaneous fragmentation of the O‐C‐P unit in the majority of cases. Indeed, this has been observed in many low‐valent early d‐block and f‐block cases [1, 3] .…”

“…Indeed, this has been observed in many low-valent early d-block and f-block cases. [1,3] Thus, there are no (OCP) À cycloaddition reactions yet reported under reducing conditions.…”

The “Hidden” Reductive [2+2+1]‐Cycloaddition Chemistry of 2‐Phosphaethynolate Revealed by Reduction of a Th‐OCP Linkage

“…The solid structure of 2 ( Figure 1) reveals Th À O, O À C, and C À P distances of 2.334(3), 1.246 (5), and 1.544 (5) , and Th-O-C and O-C-P angles of 173.1(3) and 178.8(5)8, respectively, suggesting overall [11] the dominance of PC-O À , rather than À P=C=O, resonance forms, as commonly observed when this anion is coordinated to electropositive metal ions. [3] The ThÀN amide and ThÀN amine distances are unremarkable. These data compare well to other actinide-OCP complexes.…”

Unprecedented η3-Coordination and Functionalization of the 2-Phosphaethynthiolate Anion at Lanthanum(III)

“…The (coordination) chemistry of the 2-phosphaethynolate ([OCP] -) anion continues to be a vibrant, highly topical research field in the chemical sciences [1] and has already led to the isolation of a plethora of novel or rare phosphorus-containing heterocycles, [2] the first stable singlet phosphinidene, [3] as well as many (functional) coordination compounds covering the whole periodic table [1], [4] from main group elements [5,6] and transition metals [7] to the lanthanides [8] and actinides. [9] In contrast, the chemistry of the heavier analogues, e.g.…”