Antimony pentachloride complexes

The 1,4-diketone 1,2-dibenzoylethane 151 can be transformed in one step into 3,4-dibenzoyl-l,2,5-thiadiazole 152 when treated either with preformed trithiazyl trichloride in tetrachloromethane (Equation 29) <1997J(P1)2831> or with urethane, thionyl chloride, and pyridine in benzene (Katz reagent) <2002ARK90> (see also Section 5.09.9.2.l(iii)(b)). Similarly, treatment of 1,3-diketones 153 with tetrasulfur tetranitride antimony pentachloride complex in toluene at 100 °C < 1998J(P 1 )2175 >, or trithiazyl trichloride in boiling tetrachloromethane < 1997J(P 1)2831 >, affords 4-substituted-3-aroyl-l,2,5-thiadiazoles 154 (Equation 30). 

Enamines 187 with electron-withdrawing groups in the /3-position are converted into thiadiazoles 188 in moderate yields (50-60%) on treatment with either tetrasulfur tetranitride antimony pentachloride complex <2000H(53)159> or trithiazyl trichloride <2001J(P1)662> (Equation 38 Table 12). Cyclization onto electrophilic /3-substituents was not observed, and thus the procedure offers a regiospecific synthesis of 4-substituted-3-aroyl-l,2,5-thiadiazoles. 

Unlike the reaction of alkyl aryl ketoximes with tetrasulfur tetranitride <1996CHEC-II(4)355>, the treatment of alkyl methyl ketoximes 189 with tetrasulfur tetranitride antimony pentachloride complex in either benzene or toluene at 50-80°C gave low yields (3-37%) of 3-alkyl-4-methyl-l,2,5-thiadiazoles 190 (Equation 39) <1999H(50)147>. Compounds 190 were volatile and the low yields are in part attributed to their loss as the solvent was removed in vacuo. Suprisingly, only single regioisomers were obtained. 3-Heptanone oxime 191 did, however, give a mixture of two isomers 192 and 193 (Equation 40). 

Reaction of tetrasulphur tetranitride antimony pentachloride complex (S4N4.SbCl5) with a series of primary (3-enaminones and P-enamino esters 79 in toluene at 100 °C gave reasonable yields of 3,4-disubstituted 1,2,5-thiadiazoles 80. The formation of 80 was explained by the same mechanism as that proposed for the formation of 1,2,5-thiadiazoles from 3,5-disubstituted isoxazoles with S4N4.SbCl5 complex <00H159>. 

Antimony pentachloride complexes of A-oxides of pyridine, quinoline and isoquinoline rearrange on heating to give the corresponding pyrid-2-one, carbostyril or isocarbostyril, e.g. Scheme 118 (81T1871). 

Cyclic S-N compounds including S2N2 have been reviewed. An x-ray analysis of disulfur dinitride, S2N2, with alternating sulfur and nitrogen atoms indicates a nearly square planar array with S-N distances of 1.657 and 1.651 A and angles NSN of 89.6° and SNS of 90.4°. The structure of the bis(antimony pentachloride) complex is planar S-N, 1.619 A NSN, 84.9° SNS, 95.1°. An S2N2 complex of copper (II) chloride also is planar S-N, 1.633, 1.641 A N-S-N,... 

The salts of the parent compound Cl2C=NH (IV) were synthesized by Allenstein and Schmidt ( ) in 1964, by adding hydrogen chloride to the antimony pentachloride complexes of cyanogen halides V. The compounds obtained (IV) are stable at room temperature, with the exception of the iodine derivative (IV, X=I)( ). 

Bae S-H, Kim K, ParkYJ (2000) Reactions of tetrasulfur tetranitride antimony pentachloride complex (S4N4 SbCls) with primary p-enaminones and p-enamino esters synthesis of... 

Nogaj B, Poleshchuk OKh, Kasprzak J, Koput J, EHnVP, Dolenko GN (1997)Changes in electron density distribution resulting from formation of antimony pentachloride complexes studied by X-ray fluorescence spectroscopy. Journal of Molecular Structure 406-. 145-151. 

The effectiveness of antimony fluoride is increased if it is used in conjunction with chlorine or with antimony pentachloride. The formation of either SbCl2F2 or a complex of SbF and SbCl probably accounts for the increased activity (4). 

An older, equally interesting industrial route involves condensing 2-aminoan-thraquinone in nitrobenzene in the presence of antimony pentachloride or titanium tetrachloride. Complex 97 prevents any undesirable formation of anthrim-ide (98). 

Attempts to obtain alkylcarbonium complexes by dissolving alkyl chlorides (bromides) in liquid Lewis acid halides (stannic chloride, titanium (IV) chloride, antimony pentachloride, etc.) as solvent were unsuccessful. Although stable solutions could be obtained at low temperature with, for example, t-butyl chloride, the observed N.M.R. chemical shifts were generally not larger than 0 5 p.p.m. and thus could be attributed only to weak donor-acceptor complexes, but not to the carbonium ions. The negative result of these investigations seems to indicate that either the Lewis acids used were too weak to cause sufficient ionization of the C—Cl bond, or that the solvating effect of the halides... 

Tetrakis(phenyldifluorophosphine)nickel-(0) could also be obtained, using arsenic trifluoride in the presence of catalytic amounts of antimony pentachloride, or zinc fluoride as fluorinating agents. Yields as high as 50% could be obtained, but sizable decomposition on the process of fluorination of the chlorophosphine nickel-(0) complexes in solution could not be entirely suppressed. The marked instability of zerovalent nickel-phosphine complexes in solution in organic solvents, even under strictly anhydrous and anaerobic conditions, has been noted by several workers (16,20), but is still lacking a detailed explanation. A closer examination of the system carbon tetrachloride-tetrakis(trichlorophosphine)nickel-(0) (23) showed the main pa h of the reaction to consist in the formation of hexachloro-ethane with conversion of zerovalent into bivalent nickel, while the coordinated... 

Cationic mechanisms are much more characteristic of the polymerization of oxygen heterocycles, both ethers and acetals. A wide variety of catalysts has been used, including protonic acids, such Lewis acids as boron trifluoride, phosphorus pentafluoride, stannic chloride, antimony pentachloride, titanium tetrachloride, zinc chloride, and ferric chloride, and salts of carbocations or tri-alkyloxonium ions having anions derived from Lewis acids. Some complex, coordination catalysts that appear to operate by a mechanism... 

Antimony pentachloride, in a case of acute poisoning, caused severe pulmonary oedema in the three victims, two of whom died.175 Antimony compounds form complexes with thiol groups (see Section 28.11.4), and in enzymes with thiol groups then these processes are blocked. 

Schmidt, a complex is formed between methyl azide and antimony pentachloride in methylene chloride solution.1 1 Under the influence of dry hydrogen chloride, the complex decomposes at room temperature into methylenimmonium hexachloroantimonate (26) (Scheme V). By use of deuterium chloride instead of hydrogen chloride, N-monodeuterated methylenimmonium hexachloroantimonate was obtained. 

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