Hydroxamic Acid Complexes of Rhodium

Ono percent aqueous solution of rhodium chloride was treated with concentrated solution of oxaldihydroxamic acid and a little alcohol; the mixture after acidification with, a few ml. of acetic acid was refluxed for 6-7 hours when a brown precipitate was obtained. It was filtered, washed repeatedly with hot water, alcohol and ether and finally dried over sulpharic acid. The residue was analysed (Found: Rh, 37.26; C, 13.15; H, 1.12; N, 14.69). Rh2C6H6O12,N6 requires Rh, 36.78; C, 12.85, H, 1.07 and N 15%. The hydroxamic acid behaves as a quadridentate ligand. Tho compound was insoluble in alcohol, carbon tetrachloride, acetone, ethyl acetate, ether, benzene nitrobenzene carbon disulphide phenylhydrazine, alkali and ammonia but soluble in mineral acide. The insolubility of the compound in alkali indicated the absence of acidic N-H. The enolic form of the hydroxamic acid perhaps complexes with the metal ion giving the structure