Synthetic Applications of (Me3SiNSN)2E (E = S, Se) in Chalcogen-Nitrogen Chemistry: Formation and Structural Characterization of Cl2TeESN2 (E = S, Se) and [PPh4]2[Pd2(μ-Se2N2S)X4] (X = Cl, Br)

Chalcogen bonding in synthesis, catalysis and design of materials

Chalcogen bonding is a type of noncovalent interaction in which a covalently bonded chalcogen atom (O, S, Se or Te) acts as an electrophilic species towards a nucleophilic (negative) region(s) in another or in the same molecule. In general, this interaction is strengthened by the presence of an electron-withdrawing group on the electron-acceptor chalcogen atom and upon moving down in the periodic table of elements, from O to Te. Following a short discussion of the phenomenon of chalcogen bonding, this Perspective presents some demonstrative experimental observations in which this bonding is crucial for synthetic transformations, crystal engineering, catalysis and design of materials as synthons/tectons.

Experimental and computational investigations of platinum complexes of selenium diimide and some novel selenium–nitrogen ligands

The reaction of selenium diimide Se[N(t-Bu)]2 and PtCl2 afforded an N,N′-chelated complex [PtCl2{N,N′-Se[N(t-Bu)]2}] (1) in good yield and [PtCl2{N,N′-SeO[NH(t-Bu)]2}] (2) as a minor product. Attempts to prepare 2 by direct reaction of SeOCl2 with Li[NH(t-Bu)] in toluene followed by addition of PtCl2 produced cyclic Se4[N(t-Bu)]4 in solution (77Se NMR spectrum) and a small amount of the complex [PtCl3{Se,Se′,Se″-Se4[N(t-Bu)]4}][Pt2Cl5{Se,Se′,Se″-Se3[N(t-Bu)]2}]·3MeCN (3·3MeCN), which contains tridentate Se4[N(t-Bu)]4 in the cation and the novel, acyclic bridging ligand [SeN(t-Bu)SeN(t-Bu)Se]2– in the anion. The reaction of Se[N(t-Bu)]2 with [PtCl2(NCPh)2] in THF produced the dinuclear complex [Pt2Cl6{SeN(t-Bu)C(Ph)NH}2]·2C4H8O (4·2THF) as the major product and only a few crystals of 1. The possible formation of SeO[NH(t-Bu)]2 or 2 by the reaction of Se[N(t-Bu)]2 or 1, respectively, with adventitious water and the pathway for the production of 4 were investigated through density functional theory calculations. The X-ray structures of 1, 2, 3·3MeCN, and 4·2THF have been determined.

Relativistic effects on the 125Te and 33S NMR chemical shifts of various tellurium and sulfur species, together with 77Se of selenium congeners, in the framework of a zeroth-order regular approximation: applicability to tellurium compounds

The relativistic effects on σ(Te), σ(Se), and σ(S) were evaluated separately by scalar and spin–orbit terms for various species containing Te, Se, and S nuclei. The applicability of σ^t(Te)_Rlt-so to analyze δ(Te)_obsd and the trend in the nuclei are discussed.