Alkylation of organoiron thiolate complexes

Treichel, P. M.; Schmidt, Mark S.; Koehler, Siegmund

doi:10.1016/s0022-328x(00)99259-3

Cited by 10 publications

(3 citation statements)

References 11 publications

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“…Recently, Carrano and co-workers demonstrated the efficacy of hydrogen bonding in attenuating the nucleophilicity of zinc-bound thiolates, results which may provide insight into the biological mechanism for regioselective S-alkylation of the Cys 4 Zn active site in the Ada protein. Alkylations of organometallic iron(II)−thiolates have also been examined, , demonstrating the importance of metal−thiolate orbital energies in governing the reactivity of these complexes …”

Section: Introductionmentioning

confidence: 99%

Electronic Structure Control of the Nucleophilicity of Transition Metal−Thiolate Complexes: An Experimental and Theoretical Study

et al. 2004

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New metal(II)-thiolate complexes supported by the tetradentate ligand 1,5-bis(2-pyridylmethyl)-1,5-diazacyclooctane (L(8)py(2)) have been synthesized and subjected to physical, spectroscopic, structural, and computational characterization. The X-ray crystal structures of these complexes, [L(8)py(2)M(S-C(6)H(4)-p-CH(3))]BPh(4) (M = Co, Ni, Zn), reveal distorted square-pyramidal divalent metal ions with four equatorial nitrogen donors from L(8)py(2) and axial p-toluenethiolate ligands. The reactions of the complexes with benzyl bromide produce isolable metal(II)-bromide complexes (in the cases of Co and Ni) and the thioether benzyl-p-tolylsulfide. This reaction is characterized by a second-order rate law (nu = k(2)[L(8)py(2)M(SAr)(+)][PhCH(2)Br]) for all complexes (where M = Fe, Co, Ni, or Zn). Of particular significance is the disparity between k(2) for M = Fe and Co versus k(2) for M = Ni and Zn, in that k(2) for M = Ni and Zn is ca. 10 times larger (faster) than k(2) for M = Fe and Co. An Eyring analysis of k(2) for [L(8)py(2)Co(SAr)](+) and [L(8)py(2)Ni(SAr)](+) reveals that the reaction rate differences are not rooted in a change in mechanism, as the reactions of these complexes with benzyl bromide exhibit comparable activation parameters (M = Co: DeltaH() = 45(2) kJ mol(-)(1), DeltaS() = -144(6) J mol(-)(1) K(-)(1); M = Ni: DeltaH() = 43(3) kJ mol(-)(1), DeltaS() = -134(8) J mol(-)(1) K(-)(1)). Electronic structure calculations using density functional theory (DFT) reveal that the enhanced reaction rate for [L(8)py(2)Ni(SAr)](+) is rooted in a four-electron repulsion (or a "filled/filled interaction") between a completely filled nickel(II) d(pi) orbital and one of the two thiolate frontier orbitals, a condition that is absent in the Fe(II) and Co(II) complexes. The comparable reactivity of [L(8)py(2)Zn(SAr)](+) relative to that of [L(8)py(2)Ni(SAr)](+) arises from a highly ionic zinc(II)-thiolate bond that enhances the negative charge density on the thiolate sulfur. DFT calculations on putative thioether-coordinated intermediates reveal that the Co(II)- and Zn(II)-thioethers exhibit weaker M-S bonding than Ni(II). These combined results suggest that while Ni(II) may serve as a competent replacement for Zn(II) in alkyl group transfer enzymes, turnover may be limited by slow product release from the Ni(II) center.

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Section: Introductionmentioning

confidence: 99%

Electronic Structure Control of the Nucleophilicity of Transition Metal−Thiolate Complexes: An Experimental and Theoretical Study

et al. 2004

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“…In an effort to avoid the requirement of stoichiometric amounts of Ag(I), the activation of a thiolate ligand as a leaving group was investigated. The approach is based on the work by Treichel et al, where a thiophenyl ligand was replaced by bromide, using ethylation of the sulfur as an activation process . We prepared the thiophenyl complex 13 in racemic form and activated it by methylation with methyl triflate to give 14 (not isolated).…”

Section: Resultsmentioning

confidence: 99%

Preparation and Structure of Chiral Carbene Complexes of Manganese and Iron from Terminal Alkynes

Semmelhack

Lindenschmidt

2001

Organometallics

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“…However, 3 was much more air sensitive. Other compounds of the formula (η 5 -C 5 R 5 )Fe(CO)(PR‘ 3 )(SR‘‘) (R‘‘ = alkyl, aryl) have been observed to undergo facile one electron oxidations, as well as alkylation at sulfur (CH 3 CH 2 Br, 21 °C, CHCl 3 ) . However, in view of the modest diastereoselectivities, no elaboration of the thiolate ligand of 3 was attempted.…”

Section: Resultsmentioning

confidence: 99%

Diallyl Sulfide Complexes of Chiral Iron and Ruthenium Lewis Acids: Ylide Generation and Diastereoselective [2,3] Sigmatropic Rearrangements To Give Thiolate Complexes with New Carbon Stereocenters

et al. 1996

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Reactions of the racemic iron diallyl sulfide complex [(η5-C5H5)Fe(CO)(PPh3)(S(CH2CHCH2)2)]+BF4 - and t-BuOK (CH2Cl2 or THF, −80 to −60 °C) give the thiolate complex (η5-C5H5)Fe(CO)(PPh3)(SCH(CHCH2)CH2CHCH2) (65−92%) as 77−68:23−32 mixtures of SS,RR/SR,RS Fe,S C diastereomers. Reactions of the enantiomerically pure ruthenium diallyl sulfide complexes [(η5-C5H5)Ru(S,S-chiraphos)(S(CH2CRCH2)2)]+PF6 - (5 +PF6 -; R = a, H; R = b, CH3) and t-BuOK (CH2Cl2, −98 °C) give the thiolate complexes (η5-C5H5)Ru(S,S-chiraphos)(SCH(CRCH2)CH2CRCH2) as 78:22 (8a, >99%) and 87:13 (8b, 97%) mixtures of chromatographically separable SSS/SSR P C ,P‘ C ‘,S C diastereomers. These transformations likely involve intermediate sulfur ylides as described in the title. Reactions of 8a,b with CH3I or PhCH2I and then NaI (acetone, reflux) give, via cationic methyl or benzyl sulfide complexes, enantiomerically enriched R‘SCH(CH2CRCH2)CRCH2 (R/R‘ = H/CH3, 75%; CH3/CH3, 71%; H/PhCH2 and CH3/PhCH2, >99%) and (η5-C5H5)Ru(S,S-chiraphos)(I) (6, ≥97%). Complex 6 is readily recycled to enantiomerically pure 5a,b +PF6 - (NH4 +PF6 -, CH3OH, S(CH2CRCH2)2; 94−97%).

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Alkylation of organoiron thiolate complexes

Cited by 10 publications

References 11 publications

Electronic Structure Control of the Nucleophilicity of Transition Metal−Thiolate Complexes: An Experimental and Theoretical Study

Electronic Structure Control of the Nucleophilicity of Transition Metal−Thiolate Complexes: An Experimental and Theoretical Study

Preparation and Structure of Chiral Carbene Complexes of Manganese and Iron from Terminal Alkynes

Diallyl Sulfide Complexes of Chiral Iron and Ruthenium Lewis Acids: Ylide Generation and Diastereoselective [2,3] Sigmatropic Rearrangements To Give Thiolate Complexes with New Carbon Stereocenters

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