Synthesis and Structures of [LCu(I)(SSiⁱPr₃)] (L = triphos, carbene) and Related Compounds

Abstract

The mononuclear Cu(I) complexes [LCu(I)(SSi(i)Pr3)] (L = 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos), 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes)) have been prepared by ligand displacement from [LCu(I)Cl] with (i)Pr3SiS(-). Both compounds are colorless, diamagnetic species and have been characterized structurally by X-ray crystallography. The compounds [(IMes)Cu(η(1)κ(S)-SC(O)CH3)] and [(triphos)Cu(η(1)κ(S)-SC(S)OCH3)] have been prepared in the context of synthesis aimed at [LCu(η(1)κ(S)-SCOS)] and [LCu(η(1)κ(S)-SCS2)] complexes, which are intended as synthons toward an analogue of the Mo(μ-OSCO)Cu intermediate proposed as occurring in the catalytic cycle of carbon monoxide dehydrogenase (CODH).

A W/Cu Synthetic Model for the Mo/Cu Cofactor of Aerobic CODH Indicates That Biochemical CO Oxidation Requires a Frustrated Lewis Acid/Base Pair

“…Furthermore, these complexes were isolated in the Mo V /Cu I redox state rather than the Mo VI /Cu I state needed for CO oxidation in the native enzyme, lacked dithiolate ligation at Mo to mimic the molybdopterin group, and featured coordinatively saturated Cu I sites that were therefore deactivated toward cooperative CO activation. Synthetic attempts by the groups of Tatsumi, , Holm, , and others − at overcoming some or all of those shortcomings failed to produce unsupported M–(μ 2 -S)–Cu bridges (M = Mo or W). The prevailing view from these studies is that M­(O eq )–(μ 2 -S)–Cu systems are unstable toward intermolecular O/S disproportionation that produces thermodynamically stable M­(μ 2 -S) 2 Cu cores.…”

Tethered Polynuclear Copper–Chalcogenolate Assemblies Enabled via NHC Ligation

“…Orange block-shaped crystals suitable for X-ray diffraction were obtained after 2 days. The crystals were washed with 2 × 10 mL of diethyl ether and 2 × 10 mL of pentane and dried under dynamic vacuum for further analyses (75% yield): mp 186−189 °C; 1 H NMR (CDCl 3 , 599.36 MHz, 25 °C) δ 7.51 (t, 3 J HH = 7.0 Hz, 4H, para-CH), 7.32 (d, 3 J HH = 7.6 Hz, 8H, meta-CH), 7.10 (s, 4H, NCH), 3.62 (s, 4H, Cp-H), 3.43 (s, 4H, Cp-H), 2.86 (s, 4H, CH 2 ), 2.60 (sept, 3 J HH = 7.0 Hz, 8H, CH(CH 3 ) 2 ), 1.32 (d, 3 J HH = 7.0 Hz, 24H, CH(CH 3 ) 2 ), 1.22 (d, 3 J HH = 7.0 Hz, 24H, CH(CH 3 ) 2 ); 13 ,62.21;H,6.64;N,4.40. Found: C,61.43;H,6.88;N,4.30.…”

“…Colorless block-shaped crystals suitable for X-ray diffraction were obtained after 4−5 days. The crystals were washed with 3 × 10 mL of pentane and dried under dynamic vacuum for further analyses (82% yield): mp above 260 °C; ,71.45;H,7.91;N,4.68;S,5.35. Found: C,72.06;H,8.12;N,4.47;S,5.58.…”

“…The crystals were washed with 3 × 10 mL of pentane and dried under dynamic vacuum for further analyses. Repeating the reaction in benzene at room temperature followed by pentane diffusion in the gas phase to the mother liquor yielded colorless plate crystals of 4 suitable for X-ray diffraction (60% yield): mp decomposed at ∼240−245 °C; 1 H NMR (CDCl 3 , 599.40 MHz, 25 °C) δ 7.45 (t, 3 J HH = 6.6 Hz, 4H, para-CH), 7.28 (d, 3 J HH = 6.6 Hz, 8H, meta-CH), 7.11 (s, 4H, NCH), 3.05 (s, 4H, CH 2 ), 2.63 (sept, 3 J HH = 6.4 Hz, 8H, CH(CH 3 ) 2 ), 1.91 (s, 12H, Ar−CH 3 ) 1.34 (d, 3 J HH = 6.4 Hz, 24H, CH(CH 3 ) 2 ), 1.22 (d, 3 J HH = 6.4 Hz, 24H, CH(CH 3 ) 2 ), ppm; 13 C,61.18;H,7.55;N,2.80. Found: C,58.69;H,6.05;N,2.23.…”

“…Repeating the reaction in benzene at room temperature followed by pentane diffusion in the gas phase to the mother liquor yielded colorless plate crystals of 4 suitable for X-ray diffraction (60% yield): mp decomposed at ∼240−245 °C; 1 H NMR (CDCl 3 , 599.40 MHz, 25 °C) δ 7.45 (t, 3 J HH = 6.6 Hz, 4H, para-CH), 7.28 (d, 3 J HH = 6.6 Hz, 8H, meta-CH), 7.11 (s, 4H, NCH), 3.05 (s, 4H, CH 2 ), 2.63 (sept, 3 J HH = 6.4 Hz, 8H, CH(CH 3 ) 2 ), 1.91 (s, 12H, Ar−CH 3 ) 1.34 (d, 3 J HH = 6.4 Hz, 24H, CH(CH 3 ) 2 ), 1.22 (d, 3 J HH = 6.4 Hz, 24H, CH(CH 3 ) 2 ), ppm; 13 C,61.18;H,7.55;N,2.80. Found: C,58.69;H,6.05;N,2.23. Although these results are outside the range viewed as establishing analytical purity, they are provided to illustrate the best values obtained to date as crystals of 5 precipitate with a second material.…”