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Bond Stretching and Redox Behavior in Coinage Metal Complexes of the Dichalcogenide Dianions [(SPh 2 P) 2 CEEC(PPh 2 S) 2 ] 2− (E=S, Se): Diradical Character of the Dinuclear Copper(I) Complex (E=S)
Author(s) -
Konu Jari,
Chivers Tristram,
Tuon Heikki M.
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201100891
Subject(s) - chemistry , ligand (biochemistry) , redox , isomerization , metathesis , crystallography , stereochemistry , reactivity (psychology) , diselenide , metal , medicinal chemistry , diradical , diphenyl diselenide , monomer , polymerization , inorganic chemistry , singlet state , selenium , medicine , biochemistry , polymer , receptor , alternative medicine , physics , organic chemistry , pathology , nuclear physics , excited state , catalysis
The metathetical reactions of a) [Li(tmeda)] 2 [(S)C(PPh 2 S) 2 ] (Li 2 ⋅ 3 c ) with CuCl 2 and b) [Li(tmeda)] 2 [(SPh 2 P) 2 CSSC(PPh 2 S) 2 ] (Li 2 ⋅ 4 c ) with two equivalents of CuCl both afford the binuclear Cu I complex {Cu 2 [(SPh 2 P) 2 CSSC(PPh 2 S) 2 ]} ( 5 c ). The elongated (C)SS(C) bond (ca. 2.54 and 2.72 Å) of the dianionic ligand observed in the solid‐state structure of 5 c indicate the presence of diradical character as supported by theoretical analyses. The treatment of [Li(tmeda)] 2 [(SPh 2 P) 2 CSeSeC(PPh 2 S) 2 ] (Li 2 ⋅ 4 b ) and Li 2 ⋅ 4 c with AgOSO 2 CF 3 produce the analogous Ag I derivatives, {Ag 2 [(SPh 2 P) 2 CEEC(PPh 2 S) 2 ]} ( 6 b , E=Se; 6 c , E=S), respectively. The diselenide complex 6 b exhibits notably weaker AgSe(C) bonds than the corresponding contacts in the Cu I congeners, and the 31 P NMR data suggest a possible isomerization in solution. In contrast to the metathesis observed for Cu I and Ag I reagents, the reactions of Li 2 ⋅ 4 b and Li 2 ⋅ 4 c with Au(CO)Cl involve a redox process in which the dimeric dichalcogenide ligands are reduced to the corresponding monomeric dianions, [(E)C(PPh 2 S) 2 ] 2− ( 3 b , E=Se; 3 c , E=S), and one of the gold centers is oxidized to generate the mixed‐valent Au I /Au III complexes, {Au[(E)C(PPh 2 S) 2 ]} 2 ( 7 b , E=Se; 7 c , E=S), with relatively strong aurophilic Au I ⋅⋅⋅Au III interactions. The new compounds 5 c , 6 b , c and 7 b , c are characterized in solution by NMR spectroscopy and in the solid state by X‐ray crystallography ( 5 c , 6 b , 7 b and 7 c ) and by Raman spectroscopy ( 5 c and 6 c ). The UV‐visible spectra of coinage metal complexes of the type 5 , 6 and 7 are discussed in the light of results from theoretical analyses using time‐dependent density functional theory.