Pivalate complexes of copper(ii) with aliphatic amines as potential precursors for depositing nanomaterials from the gas phase

Abstract

New copper(II) complexes with pivalate and primary aliphatic amines [Cu₂(RNH₂)₂(μ-O₂C^tBu)₄]_n, where R = ^tBu, ^sBu, ⁱPr, and Et were synthesised and characterised. These and the known complexes with tertiary triethylamine [Cu₂(Et₃N)₂(μ-O₂C^tBu)₄] were investigated for use as precursors in chemical vapour deposition (CVD) and focused electron beam induced deposition (FEBID) methods by thermal analysis and sublimation experiments. TGA studies have shown that copper derivatives in the gas phase occur even at atmospheric pressure. For preliminary CVD experiments, the selected copper compound [Cu₂(^tBuNH₂)₂(μ-O₂C^tBu)₄]_n was used. Moreover, the so-called ‘sensitivity’ to high-energy electrons studied in thin layers of compounds was confirmed by observations using electron microscopes. These results reveal that the obtained complexes can be promising for the vapour deposition methods. Additionally, the used pivalate-amine ligand system allowed four single crystals to grow through partial release of the secondary ligand in the air. The following multinuclear complexes [Cu₃(^tBuNH₂)₂(μ-O₂C^tBu)₆]_n, [Cu₃(^sBuNH₂)₂(μ-O₂C^tBu)₆]_n, [Cu₃(ⁱPrNH₂)₂(μ₃-OH)₂(μ-O₂C^tBu)₄], and [Cu₂₀(EtNH₂)₆(μ₃-OH)₂₄(OH)(H₂O)₅(NO₃)(μ-O₂C^tBu)₈](^tBuCO₂)₆·13H₂O were characterized.