Thioaldehydes complexes

The synthesis of the thioaldehyde complex 63 somewhat paralleled the synthesis outlined in Scheme 17. In this case, sulfur and hydrogens were transferred to the vinylidene ligand in a single step [Eq. (14)].187... 

Similarly, the thioaldehyde complexes 66a,b were formed via addition of thiols to the vinylidene complex 64 and elimination of ethene. The vinylidene complex 64 reacted with benzyl mercaptan to yield the isolable intermediate 65. On heating 65 lost ethene in a first-order reaction to give 66b.188 The complexes 66a-d could also be prepared from the benzyne-(hydrido) complex 67 and thiols RCH2SH (Scheme 18).188... 

The thioaldehyde complexes 81a,b were formed from the thiolato complexes 80a,b on treatment with PMe3 (Scheme 21). The thiolato compounds were obtained from 79 and MeCH2SH or PhCH2SH. Although the complexes 81a,b were stable even in refluxing benzene for several hours, they... 

Another route to thioaldehyde and thioketone complexes uses the tungstate [W(CO)5SH] as the precursor. When [W(CO)5SH] was treated with ketones in the presence of trifluoroacetic acid, thioketone complexes [W(CO)5 S = C(R1)R2 ] were formed. Analogously, thiobenzaldehyde complexes were obtained from [W(CO)sSH]- and benzaldehydes bearing electron-releasing para substituents. Benzaldehyde, benzaldehydes with electron-withdrawing substituents, and aliphatic aldehydes did not react. Presumably, the binuclear dianion [p,-S W(CO)5 2]2 is an intermediate in the reaction, as on acidification of a mixture of [ju,-S W(CO)5 2]2 and p-N, A -dimethylaminobenzaldehyde the thioaldehyde complex [W(CO)5 S = C(C6H4NMe2-p)H ] is formed.143... 

A thioaldehyde complex (93) was formed, although in very poor yield (<1%), when the l,3-dithiolane-2-thione complex 92 was deprotonated with LDA at low temperature, treated with CS2, and finally alkylated with [Et30]BF4 [Eq. (19)]. No reaction took place in the absence of CS2. Studies using 14C-labeled CS2 confirmed that CS2 was incorporated into the complex.62... 

Complexes with a bridging vinylidene ligand were also used as the starting compound for the synthesis of thioaldehyde complexes. Sequential treatment of 104 with cyclohexene sulfide, HBF4, and Li[BHEt3] gave the thioaldehyde complexes 105 [Eq. (24)].209... 

To obtain thioaldehyde complexes, Muraoka and coworkers573 have synthesized a new reagent [PPh4][W(CO)5SH] according reaction 164 ... 

These observations, along with kinetic isotope effect studies and Hammett correlation studies, support a concerted elimination by a-bond metathesis involving a four-membered transition state (Eq. 2) [23]. A large kinetic isotope effect is observed for the loss of methane from methyl amide complexes lb and lh (Eqs. 3 and 4), comparable to those observed by Buchwald and coworkers for formation of zirconium rj2-thioaldehyde complexes [25] and by Bercaw and coworkers for formation of tantalum rf- imine complexes [5a] through similar transition states. 

Several rj -thioaldehyde complexes and their reactions with electro-and nucleophiles... 

Oxidation of the cobalt atom in an a,/ -unsaturated thioaldehyde complex, 42, by trityltetrafluoroborate (64) or Ag ions (65) affords an ionic dicobalt complex, 43, containing the organosulfur figment as a bridging ligand. A zirconocene thioaldehyde complex, [ZrCp2( -SCHR)], prepared... 

The thioketene dimetallic complex 493 reacts with H to give an anionic thioacyl complex (494). Protonation of494, by cleavage of a metal - carbon bond, gives a thioaldehyde complex (495) which is stabilized by PPhj... 

While addition of 2 equiv of sodium dithiocarbamate salts to [WCl(CPh) (CO)2py2l also affords ketenyl complexes [W(C0) PhCC(0) (S2CNR2)2], with [H2NEt2][S2CNEt2] a quite different reaction occurs. Remarkably, the thioaldehyde complex [W(CO)(SCHPh)(SCNEt2)(S2CNEt2)] is formed in 96%... 

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