The structure of pentachromium(ii) extended metal atom chain [Cr(tpda)Cl] (2), which behaves as a single molecule magnet at low temperature, was investigated by Density Functional Theory (DFT) calculations and spectroscopic studies without the constraints of a crystal lattice (Htpda = N,N-bis(pyridin-2-yl)pyridine-2,6-diamine). DFT studies both in the gas phase and including CHCl solvent effects indicate that an unsymmetric structure (C point group), with pairs of formally quadruply-bonded metal ions and one terminal metal center, is slightly more stable (2.9 and 3.9 kcal mol) than a symmetric structure (D point group). Isotopically-labelled samples (2-d and 2-d) have then been prepared to aid in molecular symmetry determination by combined H andH NMR studies in dichloromethane solution. The spectra are strongly suggestive of a symmetric (D) framework, indicating fast shuttling between the two unsymmetric forms over the timescale of NMR experiments. Procedures for a high-yield Pd-free synthesis of Htpda and for site-selective post-synthetic H/D exchange of aromatic Htpda hydrogens are also reported.
A novel seed layer for the formation of slab‐like transparent copper films on glass and plastic substrates is reported, based on a mixed molecular monolayer and an ultra‐thin (0.8 nm) aluminium layer both deposited from the vapour phase, which substantially outperforms the best nucleation layer for optically thin copper films reported to date. Using this hybrid layer, the metal percolation threshold is reduced to <4 nm nominal thickness and the long‐term stability of sub‐10 nm films towards oxidation in air is comparable to that of silver films of the same thickness fabricated using the best reported seed layer for optically thin silver films to date. The underlying reason for the remarkable effectiveness of this hybrid nucleation is elucidated using a combination of photoelectron spectroscopy, small angle X‐ray studies, atomic force microscopy and transmission electron microscopy.
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