Facile synthesis of mixed-ligand bis(dicarbollyl) complexes of nickel

• Novel synthetic procedure for the synthesis of mixed-ligand nickelacarboranes.
• Two-step reaction yielding mixed-ligand Ni(IV) complexes in good yields.
• Reaction of bis(phosphine)nickelacarborane with substituted dicarbollide-dianions.
• Oxidation of the paramagnetic Ni(III) complexes to diamagnetic Ni(IV) compounds.

Four mixed-ligand bis(dicarbollyl)nickel(IV) complexes 4b-e were prepared in good yields via a two-step procedure including (1) ligand exchange reactions between the nickelacarborane complex 3,3-(PPh3)2-closo-3,1,2-NiC2B9H11 (1) and the appropriate substituted dicarbollide-dianions generated from the TBA-salts of nido-carborane anions [7,8-C2B9H11(R)]− {R = 3-[(CH2)5C16H9] (2b); 5-[m-CF3C6H4] (2c); 5-[p-CH3OC6H4] (2d); and 1-[C≡CTIPS] (2e)} in THF and (2) subsequent oxidation of the prepared paramagnetic intermediate Ni(III) complexes 3b-e by FeCl3 in acetonitrile. Target compounds were characterized using a combination of spectroscopic techniques. The structure of 4e was determined using X-ray diffraction.

A number of mixed-ligand bis(dicarbollyl)nickel(IV) complexes were prepared in good yields via ligand exchange reactions between the nickelacarborane complex 3,3-(PPh3)2-closo-3,1,2-NiC2B9H11 and various substituted dicarbollide-dianions (generated from the TBA-salts of nido-carboranes) in THF and subsequent oxidation of the prepared paramagnetic intermediate bis(dicarbollyl)nickel(III) complexes by FeCl3 in acetonitrile.Figure optionsDownload as PowerPoint slide