Aryl thiolation

Alkylthio- and arylthio-pyridazines can be prepared from the corresponding halo-substituted pyridazines by using appropriate alkyl and aryl thiolates. 

They doubtless owe their stability to the bulk of the aryl thiolate ligand they have tbp structures with equatorial nitrile that can be displaced by CO to give rare carbonyls of a metal in the +4 oxidation state. 

Ligand A anionic (e.g., halides, pseudohalides, alkyl, aryl, thiolate, alkoxide) ligand N neutral (e.g., amines, imines, phosphines, carbenes, nitriles, isonitriles, NO, CO) ligand C cationic (e.g., NO+)... 

Aryl thiolates react with aryl diazonium ions to give diaryl sulfides. This reaction is believed to be a radical chain process, similar to the mechanism for reaction of... 

In spite of the attention focused on these bulky aryl substituents, especially in main-group chemistry, aryl ligands in which crowding is caused by the presence of ortho-aryl substituents formerly received little attention. In contrast, related terphenyl-substituted phenolate derivatives (e.g., -OC6H3-2,6-Ph2) of the early transition metals have been studied for many years, and zinc terphenolate derivatives have attracted attention (vide infra). A small number of similar aryl thiolate derivatives of transition metals (e.g., Mo, Fe, and Rh) have been characterized and published (vide infra). In addition, the related ligand -C6H2-2,4,6-Ph3 (Triph) had been employed as a ring substituent in bulky porphyrins.24... 

The existence of rate-equilibrium relationships in the SN2 reactions of simple alkyl derivatives is well established (Arnett and Reich, 1980 Lewis and Kukes, 1979 Lewis et al., 1980 Bordwell and Hughes, 1982). A plot of the rate constants for a family of nucleophiles against the pKa for the nucleophiles generates linear Brensted plots whose slopes lie in the range 0.3 to 0.5. A typical example, taken from Bordwell s work (Bordwell and Hughes, 1982) is the reaction of a family of aryl thiolates with -butyl... 

The strong nucleophilicity of aryl thiolate and aryl selenolate anions of tetraphenylphos-... 

Thiolato derivatives of Mo 4- were initially elusive,197 but the use of 2,4,6-alkyl-substituted aryl thiolates has permitted the isolation of several such compounds. l,2-[Mo2Q2(NMe2)4] reacts with LiSR (R = Me, Bu ) to produce l,2-[Mo(SR)2(NMe2)4]198 and this compound reacts with RSH (R = 2,4,6-Me3C6H2) to produce [Mo2(SR)6]. [M02L6] (L = NMe2, OPr OBu ... 

When one carries out additions of RFI using a stoichiometric amount of aryl thiolates, selenates or tellurates, one obtains net perfluoroalkyl thiolation etc., with the tellurate being most reactive [272,273],... 

Structural model systems are difficult to construct for cytochrome P-450 because thiolates do not bind strongly to Fe (III) porphyrin units, and oxidation of the thiolate to disulfides accompanied by reduction to Fe(II) is common (Equation 12.5). A range of models for the Fe(III) resting state have been prepared using open iron (III) porphyrins with alkyl or aryl thiolates, however. 

Ham and coworkers85 have developed a one-pot synthetic method for the formation of aryl-alkyl sulfides, 94, from various alkyl halides and lithium aryl thiolates 93, which are prepared in situ from 92 formed by lithium—halogen exchange of 91, employing n-butyllithium (Scheme 31). The method avoids the use of unstable arylthiols and a catalyst is not required. Several aryl bromides were successfully employed in the reaction, and the corresponding sulfides were obtained in 71 to 96% yields. 

However, in acetonitrile with the ratio PhS Fe 5 1, the mononuclear tetrahedral iron complex [Fe(SPh)4]2 is formed first, which reacts with sulfur to form the iron(III) dimer [Fe SPh),]2-according to equations (67) and (68). No further reaction takes place, but addition of methanol facilitates the reductive elimination of PhSSPh from the dimer to give the 2Fen2FenI cubane complex as in equation (69). Although this series of reactions has been written for PhS-, it appears similar reactions take place with alkyl as well as aryl thiolates. 

Many model compounds have been prepared81 by reacting hemes with alkyl or aryl thiolate in organic solution. Several of them bind CO reversibly and exhibit a strong spectral resemblance to carbonylated cytochromes P450. 

Figure 7 Tailed iron porphyrins used as models of c)7ochrome P450. (a) model designed by Battersby and coworkers, attached at two points (b) TPP derivative with a pendant aryl thiol capable of bonding to the metal (c) a picket fence derivative with a pendant alkyl thiol (d) a chelated heme with a thiolate ligand (e) precursor of a model designed by Tatsimo et al., attached to the porphyrin at two points (f) another TPP derivative with a pendant aryl thiolate ...

Model hemes coordinated to phenoxides and aryl thiolates have been investigated as models of catalase and hemoglobins M (which have tyrosine substituted for either the proximal or distal histidine) and cytochromes P450 (which have the thiolate of cysteine coordinated to... 

A very large series of nitrosyl complexes, [Mo(NO)Tp X Y] has been described where X and Y are halide, alkoxide, aryloxide, alkyl or arylamide, alkyl or aryl thiolate groups. These diamagnetic Mo(NO) + species are regarded as containing 16 valence electrons, with a formal metal oxidation state of 11, assuming NO+ binding, and the metal center could... 

Louie, J., Hartwig, J. F. Transmetalation, Involving Organotin Aryl, Thiolate, and Amide Compounds. An Unusual Type of Dissociative Ligand Substitution Reaction. J. Am. Chem. Soc. 1995,117,11598-11599. 

Although the S-H bond adds readily to alkynes in a free radical chain reaction, the relative ease of addition of S-H to alkenes under the same conditions makes the reaction difficult to stop at the single addition stage. Most commonly a mixture of thiaalkenes and dithiaalkanes is obtained and, in the latter, the sulfurs are on vicinal carbon atoms. Aryl thiolates usually give geminal dithia products. Some typical examples of free radical alkyne RSH insertions are given in Table... 

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