Mechanisms of Cyaphide (CP−) Formation

✍ Scribed by Andreas Ehlers; Joseph G. Cordaro; Daniel Stein; Hansjörg Grützmacher

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 463 KB
• Volume: 119
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/ange.200702442

✦ Synopsis

Many complexes and coordination polymers with unique properties have been constructed with the cyanide ion. [1] However, analogous chemistry with the heavier phosphorus congener of cyanide has not been developed. We reported the synthesis and X-ray crystallographic characterization of a complex with a terminal cyaphide ligand, [RuH(dppe) 2 -(CP)] (2; dppe = bis-1,2-diphenylphosphinoethane). [2,3] Herein we present experimental and computational results which suggest a possible mechanism for the formation of 2.

When [RuH(dppe) 2 (P CSiPh 3 )] + (1) was treated with 1.2 equivalents of NaOPh in dry [D 8 ]THF (Scheme 1) and the subsequent reaction was monitored by 31 P{ 1 H} NMR spectroscopy, a new quintet at d = 309.5 (J PP = 27 Hz) ppm and a doublet at d = 62.7 (J PP = 27 Hz) ppm were seen for intermediate X. Over time, this intermediate species disappeared and broader resonances at d = 164.8 and 65.3 ppm appeared for product 2. When two equivalents of NaOPh (relative to 1)

were used, the rate of reaction to form the cyaphide complex 2 was accelerated. A clue to the nature of X was obtained serendipitously when the reaction of NaOPh and 1 was performed in wet acetonitrile. From this reaction a new product was detected in the 31 P NMR spectrum (d = 332.0 (qnt, J PP = 28 Hz), 67.7 (d, J PP = 28 Hz) ppm). Further investigations into this crystalline material by X-ray diffraction revealed the unique l 5 s 3 -phosphaketenylruthenium complex 3 (Figure 1).