Metallathiirenes. 4.¹ Thioaroyl Complexes of Molybdenum(II) and Tungsten(II)

Abstract

Synthetic routes to a range of thioaroyl complexes of tungsten and molybdenum are reported. Successive treatment of [M(CO)6] (M = Mo, W) with LiC6H4OMe-4·LiBr, (CF3CO)2O, and 2,2-bipyridyl (bipy) provides [M(⋮CC6H4OMe-4)Br(CO)2(bipy)], which react with methylthiirane to provide the thioaroyl complexes [M(η2-SCC6H4OMe-4)Br(CO)2(bipy)] and the dithiocarboxylate complexes [M(η2-S2CC6H4OMe-4)Br(CO)2(bipy)]. [Mo(⋮CC6H4Me-4)(CO)2{HB(pz)3}] (pz = pyrazol-1-yl), [Mo(⋮CC6H4OMe-4)(CO)2{HB(pz)3}] (obtained from [Mo(⋮CC6H4OMe-4)Br(CO)2(γ-picoline)2] and K[HB(pz)3]), and [Mo(⋮C4H3S-2)(CO)2{HB(pz)3}] (obtained directly from [Mo(CO)6], 2-thienyllithium, (CF3CO)2O, and K[HB(pz)3]) react with methylthiirane to provide primarily [Mo(η2-SCR)(CO)2{HB(pz)3}] in addition to small amounts of the corresponding dithiocarboxylates [Mo(η2-S2CR)(CO)2{HB(pz)3}], which also arise from treatment of [Mo(η2-SCR)(CO)2{HB(pz)3}] with methylthiirane or elemental sulfur. [Mo(⋮CC6H2Me3-2,4,6)(CO)2{HB(pz)3}] failed to react with methyllirane, while [Mo(⋮CC6H4OMe-4)(CO)2(η-C5H5)] provided exclusively the dithiocarboxylate derivative. The mixed selenothiocarboxylates [Mo(η2-SSeCR)(CO)2{HB(pz)3}] (R = C6H4OMe-4, C4H3S-2) are obtained by treating [Mo(η2-SCR)(CO)2{HB(pz)3}] with Li2Se2, while [Mo(η2-SOCC6H4Me-4)(CO)2{HB(pz)3}] results from hydrolysis of the product of the reaction of [Mo(η2-SCC6H4Me-4)(CO)2{HB(pz)3}] with [Me2SSMe]BF4. Alkylation of [Mo(η2-SCC6H4Me-4)(CO)2{HB(pz)3}] with [Et3O]BF4 provides the thiolatocarbene salt [Mo(η2-EtSCC6H4Me-4)(CO)2{HB(pz)3}], while the analogues [Mo(η2-MeSCC6H4Me-4)(CO)2{HB(pz)3}]BF4 and [Mo(η2-MeSCC4H3S-2)(CO)2{HB(pz)3}]BF4 result from the reactions of [Mo(⋮CR)(CO)2{HB(pz)3}] with [Me2SSMe]BF4. The reactions of these salts with the nucleophiles Li[Et3BH] and Me3CSH provide the thioalkyl complexes [Mo(η2-MeSCHC4H3S-2)(CO)2{HB(pz)3}], [Mo(η2-MeSCHC6H4OMe-4)(CO)2{HB(pz)3}], and [Mo(η2-MeSC(SCMe3)C6H4OMe-4)(CO)2{HB(pz)3}]. The heterobimetallic thioaroyl complex [MoFe(μ-SCC6H4Me-4)(CO)5{HB(pz)3}] is obtained from the reaction of [Mo(η2-SCC6H4Me-4)(CO)2{HB(pz)3}] with [Fe2(CO)9].

Reactions of Tungsten Alkylidynes with Thionyl Chloride

“…In contrast, the addition of sulfur or selenium to alkylidyne complexes of group 6 metals [M(⋮CR)L 2 (η-C 5 H 5 )] [M = Mo, W; R = C 6 H 4 Me-4, CH 2 CMe 3 ; L = CO, P(OMe) 3 ] provides dichalcocarboxylate complexes [M(E 2 CR)L 2 (η-C 5 H 5 )] (E = S, Se) . Similar compounds are obtained with cyclohexene episulfide in place of elemental sulfur; however thioacyl complexes are the initial products with methylthiirane . The electrophilic “SMe + ” transfer reagent [Me 3 S 2 ]BF 4 has been employed by Kreissl to generate bidentate thiolatocarbene complexes .…”

Metallathiirenes. 5.1 Bis- and Tris(methimazolyl)borato Thiocarbamoyl Complexes of Molybdenum(II)

“…We have reported previously the synthesis of a range of thioaroyl and thiocarbamoyl (thiocarboxamide) (Chart ) complexes of molybdenum(II) and tungsten(II), though at the time structural data were not available for these compounds. In unrelated work, our studies on the chemistry of poly(methimazolyl)borates H n B(mt) 4 - n ( n = 1, 2; mt = methimazolyl; Chart ) led to the observation of an unprecedented B−H activation process which resulted in the formation of the first metallaboratrane .…”

Reactions of Osmium Carbyne Complexes OsCl3(≡CR)(PPh3)2 (R = CH═CPh2, CH2Ar) with Bromine and Hydrogen Peroxide

“…To the best of our knowledge, the reactions of 12 and 14 with H 2 O 2 to give 13 and 15 , respectively, are the first examples of oxidation reactions of carbyne complexes to give acylcarbyne complexes. In fact, oxidation of substituents on carbyne ligands has been rarely observed previously, although a number of oxidation reactions of carbyne complexes at the metal centers or the metal–carbyne bonds are known. The only example we are aware of is the sulfuration of the PPh 2 substituent in Tp*­(CO) 2 WCPPh 2 to afford a mixture of the thiophosphorylcarbyne complex Tp*­(CO) 2 ­W­{CP­(S)­Ph 2 } and the thioacyl complex Tp*­(CO) 2 W­{η 2 -SCP­(S)­Ph 2 } …”