Thiocarbonyl complexes formation

AHf of metal silicides 5.10.3.2.1 Thiocarbonyl complexes formation 5.8.2.13.1 Tin amides reactions with metal carbonyls 5.S.5.4.3 Tin azides reactions with... 

The second problem involves the measurement of pKa values for carbonyl and thiocarbonyl derivatives. Grieg and Johnson (157) have pointed out that the measurement of pKa values for very weak bases (11) is an inaccurate and arbitrary process. Of particular difficulty for our purposes is the fact that different carbonyl derivatives may require different acidity functions. As a result of this situation, no attempt was made to make correlations of pKa data for carbonyl and thiocarbonyl derivatives with eq. (2). Because accurate pKa values can be measured for imines, these values were correlated with eq. (2), although the conformational problem remains. The imine sets were first studied by Charton and Charton (73), who correlated them with eq. (2). No correlations of data for carbonyl or thiocarbonyl derivatives with eq. (2) are extant in the literature. Bhaskar, Gosavi, and Rao (158) have reported that AG values for complex formation of substituted thioureas with iodine are a linear function of the Taft a values. Drago, Wenz, and Carlson (159) have reported similar results for complex formation between iodine and substituted amides. Oloffson (160) has reported a linear relationship between -AH for the complex of substituted N,N-dimethylamides with SbCls and the ffj constants. 

Cyclopentadienyl Carbonyl and Related Complexes.—Successive attack of CHs and CH3+ on [CpMn(CO)2(N2>] yields the azomethane complex [CpMn(CO>2 N-(Me)=NMe ], which can also be synthesized by oxidation of [CpMn(CO)2 MeN-(H)NHMe ]. Similar nucleophilic and electrophilic attacks on the dinitrogen complex using Ph and H+ gives [CpMn(CO)a N(Ph)=NH ]. The pyrrolyl nitrogen atom of [(> -C4H4N)Mn(CO)3] acts as a donor in the formation of the complexes [(OC)3Mn( -C4H4N)M(CO)2Cp] (M = Mn or Re).i The adducts RsP.CSa (R=Bu or Cy) have been assessed as reagents for the preparation of thiocarbonyl complexes. Unfortunately reactions such as [CpMn(CO)2(as-cyclo-octene)] with R3P,CSa lead mainly to [CpMn(CO)2(PR3)] with very low yields of [CpMn(CO)2(CS)].i ... 

Cyclic Carhene Complexes. The reaction of aziridines with carbonyl, thiocarbonyl, or isonitrile ligands in Mn, Re, Fe, Ru, Pd, or Pt complexes leads to formation of cycHc carhene complexes (324—331). 

Treatment of Fischer-type carbene complexes with different oxidants can lead to the formation of carbonyl compounds [150,253]. Treatment with sulfur leads to the formation of complexed thiocarbonyl compounds [141]. Conversion of the carbene carbon atom into a methylene or acetal group can be achieved by treatment with reducing agents. Treatment of vinylcarbene complexes with diborane can also lead to demetallation and formation of diols [278]. The conversion of heteroatom-substituted carbene complexes to non-heteroatom-substituted carbene complexes... 

When thiocarbonyl derivatives are treated with an excess of electrophilic carbene complex, alkenes are usually obtained [1333-1336], The reaction is believed to proceed by the mechanism sketched in Figure 4.18, closely related to the thiocarbonyl olefination reaction developed by Eschenmoser [1337], Few examples have been reported in which stable thiiranes could be isolated [1338], The intermediate thiocarbonyl ylides can also undergo reactions similar to those of carhonyl ylides, e.g. 1,3-dipolar cycloadditions or 1,3-oxathiole formation [1338], Illustrative examples of these reactions are given in Table 4.22. 

The formation of tungsten complexes of thiiranes from diarylthioketones and W(CO)5-benzylidene complex is believed to occur via a thiocarbonyl ylide-like intermediate (115). 

The relative amounts of the products depend on irradiation time, and the formation of the bis (triphenyl phosphite) chromium complex may be almost completely avoided by following the reaction with thin layer chromatography. The diastereoisomers are air stable and reasonably soluble in most organic solvents. Their infrared spectra exhibit a metal carbonyl band at 1925 cm 1 (i>co ester at 1729 cm"1) and a metal thiocarbonyl band at 1925 cm"1 (CH2C12 solution). The NMR spectra. I 5ch3 at 1.87 ppm 5co3CH3 at 3.77 ppm II 6ch3 at 1.77... 

TABLE 18. Equilibrium constants A c (in lmol 1) for the formation of 1 1 CT complexes between I2 and selected thiocarbonyl compounds in n-heptane at 25.0 °C539... 

Insertion of imsymmetrical heterocumulenes such as 0=C=X (X = S, NR), into an N-Si bond can produce two different constitutional isomers [8]. In the case of compound 1 and X = NR, R = alkyl or aryl, there is rapid insertion into both N-Si functions and the resulting situation is extremely complex with respect to the configurational (0,N-silylation) and conformational isomerism [5, 8, 10]. In contrast, 0=C=S inserts rapidly into only one N-Si bond of 1, there is no evidence for any second insertion even after several days. The formation of small amounts of pyrazine as oxidation product even under strictly anaerobic conditions suggests some electron transfer reactivity. Spectroscopic [10] and especially the structural evidence given below show that of the two conceivable constitutional isomers [11] of the insertion reaction only the 0-Si bonded species 2 with intact thiocarbonyl function is formed. 

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