Anions of π‐Acidic N‐nitrosulfonyl/carboxy Amides and Their Re Complexes

• Published in: ChemistrySelect (Weinheim) 2016-07, Vol.1 (10), p.2096-2101
• Main Authors: Bohle, D. Scott, Chua, Zhijie
• Format: Article
• Language: English
• Subjects: Ligand Effects; N Ligands; Nitrogen acids; pi-interactions
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201600277

The synthesis of the potassium salts of the nitrogen acids N‐nitroamide {N‐nitroacetamide, K[CH3C(O)NNO2] (1)}, N‐nitrosulfonamide {N‐nitro‐p‐tolylsulfonamide, K[p‐tolylSO2NNO2] (2)} and N‐nitrocarbamates {N‐nitromethylcarbamate, K[CH3OC(O)NNO2] (3), N‐nitroethylcarbamate, K[C2H5OC(O)NNO2] (4)} are described. Reaction of 1–4 with [Re(CH3CN)2(CO)2(PPh3)2](X) (X=ClO4 or BF4) gave the corresponding new Re(I) nitrogen acid complexes Re(η2‐nitrogen acid)(CO)2(PPh3)2 5–8 in good yields. Complex 5 and 6 can also be obtained from the reaction of N‐nitroacetamide (1‐H) or N‐nitro‐p‐tolylsulfonamide (2‐H) respectively with the basic Re(I) hydride complex, Re(H)(CO)2(PPh3)3. Electron withdrawing N‐Nitro derivatives are excellent η2‐ligands! These are easily made by (a) the oxidative addition of the nitrogen acid to the low valent Re complex with L=H, PPh3 or by (b) direct substitution by the anion in a bis(acetonitrile) complex L=CH3CN. The structural and spectroscopic results illustrate the π‐accepting character of these nitrogen acids.