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

Synthetic routes to a range of thioaroyl complexes of tungsten and molybdenum are reported. Successive treatment of [M(CO) 6 ] (M = Mo, W) with LiC 6 H 4 OMe-4·LiBr, (CF 3 CO) 2 O, and 2,2-bipyridyl (bipy) provides [M(⋮CC 6 H 4 OMe-4)Br(CO) 2 (bipy)], which react with methylthiirane to provide the thioaroyl complexes [M(η 2 -SCC 6 H 4 OMe-4)Br(CO) 2 (bipy)] and the dithiocarboxylate complexes [M(η 2 -S 2 CC 6 H 4 OMe-4)Br(CO) 2 (bipy)]. [Mo(⋮CC 6 H 4 Me-4)(CO) 2 {HB(pz) 3 }] (pz = pyrazol-1-yl), [Mo(⋮CC 6 H 4 OMe-4)(CO) 2 {HB(pz) 3 }] (obtained from [Mo(⋮CC 6 H 4 OMe-4)Br(CO) 2 (γ-picoline) 2 ] and K[HB(pz) 3 ]), and [Mo(⋮C 4 H 3 S-2)(CO) 2 {HB(pz) 3 }] (obtained directly from [Mo(CO) 6 ], 2-thienyllithium, (CF 3 CO) 2 O, and K[HB(pz) 3 ]) react with methylthiirane to provide primarily [Mo(η 2 -SCR)(CO) 2 {HB(pz) 3 }] in addition to small amounts of the corresponding dithiocarboxylates [Mo(η 2 -S 2 CR)(CO) 2 {HB(pz) 3 }], which also arise from treatment of [Mo(η 2 -SCR)(CO) 2 {HB(pz) 3 }] with methylthiirane or elemental sulfur. [Mo(⋮CC 6 H 2 Me 3 -2,4,6)(CO) 2 {HB(pz) 3 }] failed to react with methyllirane, while [Mo(⋮CC 6 H 4 OMe-4)(CO) 2 (η-C 5 H 5 )] provided exclusively the dithiocarboxylate derivative. The mixed selenothiocarboxylates [Mo(η 2 -SSeCR)(CO) 2 {HB(pz) 3 }] (R = C 6 H 4 OMe-4, C 4 H 3 S-2) are obtained by treating [Mo(η 2 -SCR)(CO) 2 {HB(pz) 3 }] with Li 2 Se 2, while [Mo(η 2 -SOCC 6 H 4 Me-4)(CO) 2 {HB(pz) 3 }] results from hydrolysis of the product of the reaction of [Mo(η 2 -SCC 6 H 4 Me-4)(CO) 2 {HB(pz) 3 }] with [Me 2 SSMe]BF 4 . Alkylation of [Mo(η 2 -SCC 6 H 4 Me-4)(CO) 2 {HB(pz) 3 }] with [Et 3 O]BF 4 provides the thiolatocarbene salt [Mo(η 2 -EtSCC 6 H 4 Me-4)(CO) 2 {HB(pz) 3 }], while the analogues [Mo(η 2 -MeSCC 6 H 4 Me-4)(CO) 2 {HB(pz) 3 }]BF 4 and [Mo(η 2 -MeSCC 4 H 3 S-2)(CO) 2 {HB(pz) 3 }]BF 4 result from the reactions of [Mo(⋮CR)(CO) 2 {HB(pz) 3 }] with [Me 2 SSMe]BF 4 . The reactions of these salts with the nucleophiles Li[Et 3 BH] and Me 3 CSH provide the thioalkyl complexes [Mo(η 2 -MeSCHC 4 H 3 S-2)(CO) 2 {HB(pz) 3 }], [Mo(η 2 -MeSCHC 6 H 4 OMe-4)(CO) 2 {HB(pz) 3 }], and [Mo(η 2 -MeSC(SCMe 3 )C 6 H 4 OMe-4)(CO) 2 {HB(pz) 3 }]. The heterobimetallic thioaroyl complex [MoFe(μ-SCC 6 H 4 Me-4)(CO) 5 {HB(pz) 3 }] is obtained from the reaction of [Mo(η 2 -SCC 6 H 4 Me-4)(CO) 2 {HB(pz) 3 }] with [Fe 2 (CO) 9 ].