Reactivity of Divalent Germanium Alkoxide Complexes Is in Sharp Contrast to the Heavier Tin and Lead Analogues

The chemistry of β-diketiminate germanium alkoxide complexes has been examined and shown to be in sharp contrast to its heavier congeners. For instance, (BDI)­GeOR (BDI = [{N­(2,6-ⁱPr₂C₆H₃)­C­(Me)}₂CH], R = ⁱPr, ^sBu, ^tBu) does not react with carbon dioxide to form a metal carbonate complex. Addition of aliphatic electrophiles, such as methyl iodide or methyl triflate, results in the net oxidative addition to the germanium, giving cationic tetravalent germanium complexes, [(BDI)­Ge­(Me)­OR]­[X] (X = I, OTf). An examination of the contrasting reactivities of the alkoxide ligand and the germanium loan pair with Lewis acids yielded the unusual germanium­(II)–copper­(I) adduct, {μ²-Cu₂I₂}­[(BDI)­GeO^tBu]₂. This complex not only displays a rare example of a divalent Ge–Cu bond, but is the first example in which a planar Cu₂I₂ diamond core possesses a three-coordinate copper bound to another metal center.