A Different Sort of CP

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Science  08 Sep 2006:
Vol. 313, Issue 5792, pp. 1365
DOI: 10.1126/science.313.5792.1365b

To organometallic chemists, a “Cp” notation in molecular formulas is well understood to signify the widely used cyclopentadienyl ligand C5H5. The absence of confusion engendered by this abbreviation highlights the elusiveness of the cyaphide ligand CP: an analog of cyanide in which phosphorus replaces nitrogen. Cordaro et al. have succeeded in coaxing a precursor toward this long-sought diatomic and report isolation of a stable ruthenium complex coordinated to cyaphide through the carbon. Their synthetic route proceeds from a triphenylsilyl (Ph3Si)-coordinated CH2PCl2 fragment to the Ph3Si-C≡P phosphaalkyne through dehydrohalogenation. This molecule coordinates to a cationic Ru center to yield a stable complex that was characterized by x-ray crystallography. Addition of fluoride to a solution of this compound surprisingly led to attack at P rather than at the traditionally fluorophilic Si center. However, phenoxide proved a more cooperative nucleophile, liberating CP from the silyl cap. The resulting complex was characterized crystallographically and by nuclear magnetic resonance spectroscopy in solution; the vibrational spectrum revealed a C≡P stretching band at 1229 cm−1. — JSY

Angew. Chem. Int. Ed. 45, 10.1002/anie.200602499 (2006).

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