Title
Phosphorescence and Structure of a Tetrameric Copper(I)-Amide Cluster
Document Type
Article
Publication Date
7-27-1998
Abstract
The colorless copper(I) cluster [CuN(Si(CH3)3)2]4, which contains a square-planar Cu4N4 core, phosphoresces in CH2Cl2 solution (λmax, 512 nm; lifetime, 30 μs) and in the solid state at room temperature. Its electronic absorption spectrum in CH2Cl2 consists of two intense bands at 283 and 246 nm; these transitions, as well as the phosphorescence, are likely to involve population of MOs reflecting substantial Cu⋯Cu interactions. Solid [CuN(Si(CH3)3)2]4 luminesces with approximately the same spectrum as that of the CH2Cl2 solutions. At 77 K, the solid-state luminescence red-shifts slightly (λmax, 524 nm) and narrows substantially (fwhm, 2400 cm-1; vs 3500 cm-1 at 300 K); the emission lifetime in glassy Et2O solution is 690 μs. X-ray analysis of crystals of [CuN(Si(CH3)3)2]4 at 130 and 296 K shows that, although the previously reported structure solution (in space group I2/m, with the molecules on 2/m sites; Eur. J. Solid State Inorg. Chem. 1992, 29, 573-583) is approximately correct, the lattice is actually primitive, P2/n, and the only crystallographically required symmetry element for the molecule is a 2-fold axis. C24H72Cu4N4Si8: monoclinic, space group P2/n, Z = 2. At 130 K, a=9.285(3) Å, b = 13.393-(3) Å, c = 17.752(5) Å, and β = 90.53(2)°. [At 296 K, a = 9.3773(4) Å, b = 13.5836(7) Å, c = 17.814(2) Å, and β = 90.207(7)°.] At 130 K, the Cu and N atoms in the cluster are planar within 0.007 Å, and the Cu-N and Cu⋯Cu distances are 1.917(4)-1.925(4) and 2.6770(7)-2.6937(7) Å, respectively. Despite the low volatility of the compound, it can be used as a precursor for chemical vapor deposition (CVD) of copper metal, under H2 carrier gas, with both source and substrate at ca. 200 °C. Smaller amounts of Cu metal films are also deposited when the substrate temperature is as low as 145 °C (in the dark) or 136-138 °C (under Pyrex-filtered Xe arc lamp illumination). Thus, Cu CVD with this precursor shows slight photochemical enhancement.
Publication Source (Journal or Book title)
Inorganic Chemistry
First Page
3785
Last Page
3791
Recommended Citation
James, A., Laxman, R., Fronczek, F., & Maverick, A. (1998). Phosphorescence and Structure of a Tetrameric Copper(I)-Amide Cluster. Inorganic Chemistry, 37 (15), 3785-3791. https://doi.org/10.1021/ic971341p