1248544-26-4Relevant academic research and scientific papers
Sulfur donor atom effects on copper(I)/O2 chemistry with thioanisole containing tetradentate N3S ligand leading to μ-1,2-peroxo-dicopper(II) species
Lee, Yunho,Lee, Dong-Heon,Park, Ga Young,Lucas, Heather R.,Narducci Sarjeant, Amy A.,Kieber-Emmons, Matthew T.,Vance, Michael A.,Milligan, Ashley E.,Solomon, Edward I.,Karlin, Kenneth D.
, p. 8873 - 8885 (2010)
To better understand the effect of thioether coordination in copper-O 2 chemistry, the tetradentate N3S ligand LASM (2-(methylthio)-N,N-bis((pyridin-2-yl)methyl)benzenamine) and related alkylether ligand LEOE (2-ethoxy-N,N-bis((pyridin-2-yl)methyl)ethanamine) have been studied. The corresponding copper(I) complexes, [(LASM)Cu I]+ (1a) and [(LEOE)CuI]+ (3a), were studied as were the related compound [(LESE)Cu I]+ (2a, LESE = (2-ethylthio-N,N-bis((pyridin- 2-yl)methyl)ethanamine). The X-ray structure of 1a and its solution conductivity reveal a monomeric molecular structure possessing thioether coordination which persists in solution. In contrast, the C-O stretching frequencies of the derivative Cu(I)-CO complexes reveal that for these complexes, the modulated ligand arms, whether arylthioether, alkylthioether, or ether, are not coordinated to the cuprous ion. Electrochemical data for 1a and 2a in CH 3CN and N,N-dimethylformamide (DMF) show the thioanisole moiety to be a poor electron donor compared to alkylthioether (1a is ～200 mV more positive than 2a). The structures of [(LASM)CuII(CH 3OH)]2+ (1c) and [(LESE)CuII(CH 3OH)]2+ (2c) have also been obtained and indicate nearly identical copper coordination environments. Oxygenation of 1a at reduced temperature gives a characteristic deep blue intermediate [{(L ASM)CuII}2(O22-)] 2+ (1bP) with absorption features at 442 (1,500 M -1 cm-1), 530 (8,600 M-1 cm-1), and 605 nm (10,400 M-1 cm-1); these values compare well to the ligand-to-metal charge-transfer (LMCT) transitions previously reported for [{(LESE)CuII}2(O2 2-)]2+ (2bP). Resonance Raman data for [{(LASM)CuII}2(O2 2-)]2+ (1bP) support the formation of μ-1,2-peroxo species ν(O-O) = 828 cm-1(Δ( 18O2) = 48), νsym(Cu-O) = 547 cm -1 (Δ(18O2) = 23), and νasym(Cu-O) = 497 cm-1 (Δ(18O 2) = 22) and suggest the LASM ligand is a poorer electron donor to copper than is LESE. In contrast, the oxygenation of [(LEOE)CuI]+ (3a), possessing an ether donor as an analogue of the thioether in LESE, led to the formation of a bis(μ-oxo) species [{(LEOE)CuIII}2(O 2-)2]2+ (3bO; 380 nm, ε ～ 10,000 M-1 cm-1). This result provides further support for the sulfur influence in 1bP and 2bP, in particular coordination of the sulfur to the Cu. Thermal decomposition of 1bP is accompanied by ligand sulfoxidation. The structure of [{(LEOE) CuII(Cl)}2]+ (3c) generated from the reductive dehalogenation of organic chlorides suggests that the ether moiety is weakly bound to the cupric ion. A detailed discussion of the spectroscopic and structural characteristics of 1bP, 2bP, and 3bO is presented.
