Abstract : CuI reacts with SEt(2) in hexane to afford the known strongly luminescent 1D coordination polymer (
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Abstract : CuI reacts with SEt(2) in hexane to afford the known strongly luminescent 1D coordination polymer (Et(2)S)(3)Cu(4)(mu(3)-I)(4)}(n) (1). Its X-ray structure has been redetermined at 115 235 and 275 K in order to address the behavior of the cluster-centered emission and is built upon Cu(4)(mu(3)-I)(4) cubane-like clusters as secondary building units (SBUs) which are interconnected via bridging SEt(2) ligands. However we could not reproduce the preparation of a coordination polymer with composition (Et(2)S)(3)Cu(4)(mu(3)-Br)(4)}(n) as reported in Inorg. Chem. 1975 14 1667. In contrast the autoassembly reaction of SEt(2) with CuBr results in the formation of a novel 1D coordination polymer of composition (Cu(3)Br(3))(SEt(2))(3)(n) (2). The crystal structure of 2 has been solved at 115 173 195 and 235 K. The framework of the luminescent compound 2 consists of a corrugated array with alternating Cu(mu(2)-Br)(2)Cu rhomboids which are connected through two bridging SEt(2) ligands to a tetranuclear open-cubane Cu(4)Br(4) SBU ligated on two external Cu atoms with one terminal SEt(2). The solid-state luminescence spectra of 1 and 2 exhibit intense halide-to-metal charge-transfer emissions centered at 565 and 550 nm respectively at 298 K. A correlation was also noted between the change in the full width at half-maximum of the emission band between 298 and 77 K and the relative flexibility of the bridging ligand. The emission properties of these materials are also rationalized by means of density functional theory (DFT) and time-dependent DFT calculations performed on 1.
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