Synthesis of Trinuclear, Dinuclear and Mononuclear Carbamato-Zinc Complexes from Tetranuclear Precursors: A Top-Down Synthetic Approach to New Carbamates

In this work we report on the synthesis of new mono-, bi- and trinuclear carbamato-Zn complexes by reaction of the tetranuclear precursor [ZnEt(O2CNR2)](4) (R = iPr and iBu) with the nitrogen bases pyridine, N,N,N',N'-tetramethylguanidine (tmg) and bis(N,N,N',N'-tetramethylguanidino)naphthalene (btmgn). The only reaction product obtained with pyridine is the dinuclear complex [(py)ZnEt(O2CNR2)](2). In the case of reaction of [ZnEt(O2CNR2)](4) with tmg, the dinuclear species [(tmg)ZnEt(O2CNR2)](2) (for molar ratios of 1:4) and the mononuclear bis-carbamato complex [(tmg)(2)Zn-(O2CNR2)(2)] (for molar ratios of 1:8) were obtained. Finally, the mono- and trinuclear carbamates [(btmgn)ZnEt(O-2-CNR2)] and [(btmgn)Zn3Et3(O2CNR2)(3)] were formed in the reaction between [ZnEt(O2CNR2)](4) and btmgn (molar ratios 1:4 and 1:2, respectively). All products were structurally characterized by X-ray diffraction. Using this top-down approach the synthesis of a variety of oligonuclear carbamato-Zn complexes becomes possible. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)