Reduction of [Mo2O5] by mercaptopropionic acid in an aqueous medium. Isolation and characterization of a dinuclear oxo- and 3-sulfido-proprionato(2-)-bridged molybdenum(IV) compound

Abstract

Reaction of Cp à 2 Mo 2 O 5 with HSCH 2 CH 2 COOH in acidic (by CF 3 COOH) 50:50 MeOH-H 2 O solvent at room temperature yields compound Cp à 2 Mo 2 (l-O)(l-SCH 2 CH 2 CO 2 ) 2 , a dinuclear diamagnetic Mo IV compound with a two-leg-sharing bis(four-legged piano stool) structure and a Mo-Mo distance of 2.6833(6) Š. A reaction monitoring by ESI MS shows the formation of an intermediate 18 mass units heavier, interpreted as a dihydroxo analogue. Electrochemistry shows a reversible, pH independent oxidation process and an irreversible, pH-dependent reduction process. Contrary to a recently published analogous reaction with the closely related HSCH 2 COOH substrate, this process does not lead to C-S bond cleavage.

A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc–CH2CH2–S–S–CH2CH2–Fc

“…For example, the S–S bond length of the related literature complex, (2 RS ,5 SR )-2,5-diferrocenyl-1,6-dibenzoyl-3,4-dithiahexane, A , is 2.019 Å . This value appears to be representative for complexes containing a −CH 2 –CHR–S–S–CHR–CH 2 – chain fragment in its structure. − By contrast, the S(1)–C(1) and S(2)–C(13) bond distances of 20 are on average 0.01–0.03 Å shorter than in these cited complexes. The C(1)–S(1)–­S(2)–C(13) dihedral angle of 20 , 90.2°, also compares well with the average of those of the cited literature complex (86.7°).…”

Reaction of [Cp∗2W2O5] with mercaptocarboxylic acids: Addition rather than reduction. Isolation and characterization of Cp∗WO2(SCH2CH2COOH)

“…It is important to underline that the solution color during all these manipulation remained pale yellow, consistent with the fact that the metal maintains its d 0 configuration for the oxidation state þ6. During the analogous reaction of the Mo congener, on the other hand, the metal reduction to Mo IV was accompanied by a color change to deep red [19].…”

“…A few years ago, we have reported on the interaction between [Cp * 2 Mo 2 O 5 ] and mercaptocarboxylic acids, HS(CH 2 ) n COOH (n ¼ 1, mercaptoacetic or thioglycolic acid [18]; n ¼ 2, mercaptopropionic acid [19]), which resulted in the isolation and characterization of dinuclear Mo IV products, [Cp * 2 Mo 2 (m-S)(m-SCH 2 COO) 2 ] in the first case and [Cp * 2 Mo 2 (m-O)(m-SCH 2 CH 2 COO) 2 ] in the latter. One of the reasons for investigating the interaction of these substrates, in particular the thioglycolic acid, with the Mo VI complex was as model for the action of cysteine in molybdenum hydroxylase enzymes [20].…”

High oxidation state organomolybdenum and organotungsten chemistry in protic environments

“…A comparison of the results obtained for the reduction of Compound [Cp * 2 Mo 2 O 5 ] has also been reduced by compounds containing a S-H bond, namely HS(CH 2 ) n COOH (n = 1, 2) in an aqueous environment (MeOH-H 2 O acidified with CF 3 COOH) [144,145]. These reactions leads to very similar dinuclear products of Mo IV with formula [(Cp * Mo) 2 (-S(CH 2 ) n CO 2 ) 2 (-E)], curiously differing by the nature of E (S for n = 1 [144] and O for n = 2 [145]), see Scheme 10.…”

“…These reactions leads to very similar dinuclear products of Mo IV with formula [(Cp * Mo) 2 (-S(CH 2 ) n CO 2 ) 2 (-E)], curiously differing by the nature of E (S for n = 1 [144] and O for n = 2 [145]), see Scheme 10. The electrons for the reductions are provided by the S-H bonds, yielding compounds HOOC(CH 2 ) n SS(CH 2 ) n COOH which cocrystallize in each case with the organometallic product as H-bonded interstitial molecules.…”