Thioketones complexes

Thus, pentacarbonyl(thioketone) complexes [M(CO)5L] were prepared by irradiation of solutions of [M(CO)6] (M = Cr, Mo, W) in the presence of thioketones L (L = thiobenzophenone, adamantanethione)119 [Eq. (4)] and by refluxing solutions of [Mo(CO)6] in tetrahydrofuran (THF) in the presence of L = p,p -disubstituted thiobenzophenones, thiofenchnone, and thiocamphor, respectively.120 The formation of two diastereomers of the thiocamphor complex was observed, probably due to a high inversion barrier at sulfur. Only one isomer of the thiofenchnone complex could be detected. However, fluxional behavior could not be ruled out.120... 

Binuclear thioketone complexes containing an S = C-C=C fragment were obtained when [ (775-CsH5)Mo(CO)3 2] was treated in refluxing benzene with the thiones thiosantonin and androsta-l,4-diene-17-one-3-thione. The heterodiene coordinates via the S=C moiety in a 172 mode to one metal and via the C = C bond to the other metal.124... 

In addition to group 6 metal heterocarbonyl complexes, some thioketone complexes of other metals have also been prepared by the substitution route. The synthesis of the binuclear complex [Mn(CO)2 S = C(Ph)[(T75-C5FLt) Mn(CO)3] (775-C5H5)] (5) was achieved by reaction of [Mn(CO)2(thf) ( -CsHs)] with cymantrenyl(phenyl)thioketone." Similarly, the tetracar-... 

With some complexes, thiobenzophenone coordination is succeeded by an orthometallation. Photolysis of [Re2(CO)io] in the presence of various thiobenzophenones yielded, as expected, the binuclear complexes [Re2 (CO)4V-S = C(C6H4R-/>)2 ] (7). On subsequent thermolysis the monomeric orthometallated thioketone complexes 8 were formed (Scheme 2).125 In the thermal reaction at elevated temperatures the orthometallated com-... 

Modifications of the route described earlier are (a) the conversion of [M(CO)6] (M = Mo, W) into the chloro-bridged binuclear trianions 10, which subsequently react with S = C(C6H4OMe-p)2 to give the thioketone complexes, and (b) reduction of [W(CO)6] by sodium amalgam to give the dianion [W2(CO)i0]2 and treatment of the latter with thiobenzophenones, adamantanethione, or thiocamphor (Scheme 3).128... 

The dimeric thioketone complex 13 was obtained from [PdCl4]2- and thiopivaloylferrocene [Eq. (5)].137... 

The reactivity of the complexes 25 is similar to that of a dimeric-orthometallated thioketone complex obtained by the reaction of 2,5-... 

Several other reactions of thiophene complexes lead to thioaldehyde or thioketone complexes.78 113 114,154-162 Some examples are summarized in Scheme 11. 

The first examples of a chalcogen insertion into a transition metal-carbene bond were reported in 1981. Stirring solutions of the pentacarbonyl-(diarylcarbene)tungsten complexes 39 in pentane in the presence of solid sulfur afforded the thioketone complexes 40 [Eq. (8)].171 The reaction rate increased considerably when pentane was replaced by CS2 as the solvent due to the higher solubility of elemental sulfur in CS2. 

The reaction of an osmium carbene cluster containing the cyclic carbene ligand = C(CH=CH)2C(Ph)H which is side on bound to a nonacarbo-nyltriosmium unit with either elemental sulfur/NEt3 or cyclohexene sulfide also afforded a rf-thioketone complex.184... 

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... 

In a closely related reaction the thioketene complex 106210 was reduced by sequential addition of H and H+ to give the thioketone complex 107. However, compared to the reaction of 104 the sequence of H+ and H addition is inverse. Complex 107 is coordinatively unsaturated and therefore added PPh3 rapidly (Scheme 25).109... 

The cleavage of the S = C thioaldehyde bond was observed when the manganese thioketone complex related to 8 (Scheme 2 R1 = R2 = NMe2) was treated with LiAlD4. The C(C6H4OMe-p)2-moiety of the complex was recovered as tetra(p ra-methoxyphenyl)ethane bearing a deuterium in the ortho position of two vicinal phenyl groups each and additionally two deuterium atoms on the ethane skeleton.127... 

Tile behavior of /3-moiiooxo derivatives of 4-chlomaiioiies (27) toward morpholine was rather complex (98JOC9840). Tlius, the proposed thio-ketoiie 5-sulhde intermediates 28 would dimerize into either 1,2,4,5-tetrathianes 29 in a two-step manner or to 1,3,4,5,6-oxatetrathiocins 30 by a [5 + 3] cycloaddition. Meanwhile, the formation of oxadithiins 31 and 1,2,4-trithiolanes 32 is suggestive of the disproportionation of 28 into the thioke-tones 33 and the thioketone 5 -disulhdes 34. Tlie oxadithiins 31 correspond to a Diels-Alder dimer of 33, and the 1,2,4-trithiolanes 32 correspond to cycloadducts of 33 and 34. 

Diaryl thioketones are converted by diiron enneacarbonyl into products of orthometallation.141 Oxidative or photochemically induced deligation of these complexes provides an unusual and valuable synthetic entry into compounds in the uncommon isobenzothiophene category142,151 (Scheme 84). Moreover, the photochemical procedure provides the novel complex, (tetracyanoethylene)tetracarbonyl iron. The orthometallated complexes (68) can also be used to prepare isobenzofurans (see Section IV,B,5). 

A nice example of a degenerate rearrangement has been reported for the complex pentacarbonyltungsten(0)-thioaldehyde-l,2-dithiol 177 (R = H) or the thioketone-1,2-dithiol complex 177 (R = CH3). These compounds (obtained by the reaction of silver nitrate with tetraethylammonium pentacar-bonyliodotungstate(O) in the presence of l,6,6 z -trithiapentalenes) appeared to exist as an equilibrium mixture of the two isomers 177/178 (Scheme IV.70) [83JCS(CC)289]. The symmetrically substituted 1,2-dithiol (R = CH3, R = H) displays fluxional behavior as appears by NMR spectroscopy... 

The thioketo tautomer in the pyrolysis products is detectable by infrared. It shows strong absorption at 7.85 p, attributable to the C=S group. This absorption is at shorter wavelengths than that assigned to C=S absorption in more complex thioketones (37, 38). The thioenol tautomer absorbs at 3.93 p for SH, at 6.15 p for C=C, and at 11.55 p for =CH2. 

There are a considerable number of complexes of thioketones, thioamides, thioacids and thiourea, some examples being (68) and (69).532,536... 

The most straightforward route to heteroaldehyde and heteroketone complexes is the substitution of a heterocarbonyl compound for another coordinated ligand. This method is naturally restricted to heteroaldehydes and heteroketones stable in the uncoordinated form, i.e., is usually restricted to thioketones and a few stable seleno- and tellurocarbonyl compounds.141718,27118 In most cases, metal carbonyls or solvent complexes of metal carbonyls were used as the complex precursors. The photochemically or thermally induced loss of the ligand to be replaced is followed by coordination of the heterocarbonyl compound [Eq. (3)]. 

The moderate yield of cyclopalladated products could be increased using ligand exchange reactions starting from another cyclopalladated complex.131 Other thioketones such as thioxanthone, dithioxanthone, and thio-chromone derivatives react in a similar way, affording cyclopalladated compounds.132... 

Coordinated olefins are also readily displaced by thioketones, e.g., stil-bene, in the molybdocene complex 14 by thiobenzophenone to form the complex 15 [Eq. (6)].138 Similarly, thiobenzophenone is substituted for ethene in [Rh(C2H4)(PMe3)(7/5-C5H5)] to yield [Rh(PMe3)(V-S = CPh2) ( -C5H5)]. m... 

Even one phosphine ligand in [Co(PR3)2( 175-CSHS)] (PR3 = PMe3, PMe2Ph) could be replaced by S = CPh2 to afford [Co(PR3)(V-S = CPh2)(775-C5H5)] complexes in which the thioketone ligand is bound via a sulfur lone pair.139... 

Complexes with a,/3-unsaturated thioketones as ligands (49) were obtained in addition to other compounds when [(CO)5M=C(OEt)Aryl] (M = Cr, Aryl = Ph, C4H6Ph-o M = W, Aryl = Ph) were treated at -78°C with LiC(S)NMe2 [prepared from HC(S)NMe2 and LiNEt2 at -100°C] and then protonated at ambient temperature with acetic acid [Eq. (10)]. However, the yield of 49 was rather low (3-8%).96... 

Complexes with related chelating thioketone ligands are reversibly formed on protonation of enethiolato complexes of iron.101... 

The reactions of dinuclear thioaldehyde and -ketone complexes with PR3 take a different course. When the dimeric complexes 112 are treated with PMe3 a Ti-S bond in 112 is cleaved and the monomeric complexes 113 are reversibly formed (see Scheme 26), 69 The reaction of 112 with benzene-thiol led to a Ti-C cleavage and formation of 1,3-propanedithiolato-(phenylthiolato) complex.69 The reaction of binuclear p-191 rf-thioketone molybdenum complexes related to 115 (M = Mo, E = S, R = Aryl) with P(OEt)3 also gave mononuclear complexes [Mo(CO)2(Et) i72-S = C(Aryl)2 (i75-C5H5)] by a rather complicated reaction sequence. When other phosphites were employed additionally binuclear complexes derived from addition of the phosphite to one molybdenum atom were isolated.225... 

An interesting reaction is that of the mononuclear [W(CO)5(SH)] and the SH- -bridged dinu-clear /i-HS W(CO)s complexes with acetic anhydride to give the thioacetate complex [(MeCOS)W(CO)5]. The SH complexes react with aliphatic ketones and aromatic aldehydes to yield the complexes [(R2C=S)W(CO)5] and [(RCHS)W(CO)s] of these otherwise unstable thioketones and thioaldehydes.142... 

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