Dibenzothiophene complexes

The 77 -bound benzo[/ ]thiophene and dibenzothiophene complexes of iridium undergo reduction to the corresponding 77-complexes by hydride reaction with 2 mol of Red-Al results in addition of two H to give the cyclohexadiene complexes (Scheme 78) <2000CCR63>. 

Bonded metal benzothiophene and dibenzothiophene complexes Metal j -S-bonded thiophene complexes as adsorbents for the removal of dibenzothiophenes Conclusion... 

RuCl2(PPh3)2 reacts with 4-R2P-dibenzothiophene (R = Ph, p-Tol) and forms 303, in which the dibenzothiophene ligand is coordinated to ruthenium via the phosphorus and sulfur atoms [84JA5379, 87JOM(318)409]. The donor ability of the sulfur atom is relatively weak. Complex 303 (R = Ph) is able to add carbon monoxide and yield the monocarbonyl adduct. 

The rhodium and iridium complexes of dibenzothiophene (L) reveal an interesting case of linkage isomerism (91IC5046). Thus, the ti S) coordinated species [MCp LCb] on thermolysis with silver tetrafluoroborate afford the Ti -coordinated dicationic species. 

It should be noted, however, that this reaction sequence may be different from what may actually be occurring in the reactor. The reactions proceed at different rates depending on the process variables. Hydrodesulfurization of complex sulfur compounds such as dibenzothiophene also occurs under these conditions. The desulfurized product may crack to give two benzene molecules ... 

These dienes are valuable for the Diels-Alder based synthesis of dibenzofurans, dibenzothiophenes, carbazoles and other classes of complex polycyclic heterocyclic compounds. Scheme 2.32 summarizes some of the cycloadditions [81] of 2-vinylbenzofurans (80). 

No significant pseudo-contact shifts could be induced in the spectra of dibenzothiophene, its sulfoxide, or its sulfone, with Eu(dpm)3 although a marked shielding of the protons of one ring was observed in the spectrum of the chromium tricarbonyl complex of dibenzothiophene,presumably due to a contact shift mechanism. 

IR spectroscopy has been used to study the equilibrium constant and hydrogen-bond shifts of a phenol-dibenzothiophene 7r-complex. ... 

Dibenzothiophene acts as a 7r-electron donor and readily forms complexes with known electron acceptors. In such cases the electronic spectrum of a solution of the two compounds shows a new absorption band, usually in the visible region. The order of donor strengths of several o,o -bridged biphenyls has been estimated from their respective charge-transfer spectra and found to be carbazole > fluorene > dibenzothiophene >dibenzofuran. Dibenzothiophene forms complexes with tetracy-anoethylene, various polynitro derivatives of fluorenone, > naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, and tetra-methylmic acid. ... 

Electron donation by potential carcinogens, such as 2-acetylaminodi-benzothiophene, has been estimated from the strength of their charge-transfer complexes with chloranil in acetonitrile. - In this context it should be noted that the hydrogen bonding of phenol to the 77-electrons of dibenzothiophene has been studied and that a thiourea adduct has proved useful in the removal of dibenzothiophene from oil. - ... 

Dibenzothiophene 5-oxide reacts with triaryltin chlorides to give complexes which show bacteriostatic and fungistatic properties, and a chromium tricarbonyl complex of dibenzothiophene has been described. ... 

A complex reducing agent (CRA), dubbed NiCRA-bpy, was 99% effective in converting thianthrene into diphenyl over 18 hrs over 89 hrs, benzene (83%), diphenyl (8%), and dibenzothiophen (3%) were the products. The reductant was a4 2 1 2 mixture of NaH, /-AmONa, Ni(OAc)2, and bpy (88TL2963). 

This statement could well be expanded to include studies describing the kinetics of model compounds. In reviewing the literature, one finds that there are almost as many kinetic representations as there are researchers and/or model compounds. Even the same authors have found it necessary to use different equations to describe the different responses to inhibitors for closely related sulfur species such as thiophene, benzothiophene, and dibenzothiophene (104, 122, 123). The inhibiting effect of H2S for the hydrogenation of a simple molecule, such as toluene, has been found to require extremely complex equations to adequately describe mathemati-... 

Alkyl- or aryl-dibenzothiophenes are conveniently prepared from the 2-arylthio-cyclohexanones, which are readily cyclized and dehydrogenated to yield the respective 1-, 2-, 3- or 4-substituted dibenzothiophenes (382 equation 9 Section 3.15.2.3.2). More complex polycyclic systems are available, using suitable aryenethiols, such as naph-thalenethiols, and 2-bromo-l-tetralone to synthesize the appropriate 2-arylthio ketones. Diaryl sulfides can be converted to dibenzothiophene derivatives in satisfactory yields by photolysis in the presence of iodine (equation 10) (75S532). Several alkyldibenzothiophenes with substituents in the 2- and/or 3-positions were prepared in satisfactory yield by the condensation of dichloromethyl methyl ether with substituted allylbenzo[6]thiophenes (equation 11) (74JCS(P1)1744). 

J-Bonded metal complexes, hydrodesulfurization models with benzothiophene, 1, 769 with dibenzothiophene, 1, 769 Bonding studies energetics, 1, 285 overview, 1, 573—603 ring size effects, 1, 396 strength, 1, 609... 

As complex as the desulfurization of thiophene might appear, projection of the kinetic picture to benzothiophene and dibenzothiophene, and to their derivatives, is even more complex. As has already been noted for bond energy data, kinetic data derived from model compounds cannot be expected to include contributions from the various steric effects that are a consequence of complex molecules containing three-dimensional structures. Indeed, such steric effects can lead to the requirement of additional catalyst and process parameters for sulfur removal (Isoda et al., 1996a, 1996b). 

Figure 3. GC-FID chromatograms for thiophene compound fractions from Alberta petroleums. The peak labels are as follows 1. dibenzothiophene, 2. 4-methyldibenzothiophene, 3. 2- and 3-methyldibenzothiophene and 4. 1-methyldibenzothiophene. Samples are arranged in order of their depth of burial. Note the shift toward lower molecular weight compounds and a reduction in the amount of the unresolved complex mixture with increasing depth of burial. (Reproduced from Reference 34. Copyright 1989, American Chemical Society.)...

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