Thioether-ligated nickel(I) complexes for the activation of dioxygen

The preparation of phenyltris[1-adamantyl(thiomethyl)]borate [PhTtAd], which incorporates the large 1-adamantyl thioether substituent, is described. This derivative was sought to permit the preparation of four-coordinate nickel(I) complexes. Following a synthetic scheme for the related tert-butyl ligand, [PhTtBut], the following complexes were prepared and characterized fully, [PhTtAd]Ni(CO), [PhTtAd]Ni(PMe3) and [ʹ2PhTtAd]Ni((eta)2-CH2SAd). The last species is a degradation product resulting from attempted reduction of the nickel(II) precursor, [PhTtAd]NiCl, in the absence of a ligand suitable for trapping the nickel(I) fragment.