Thiocarbonyl complex

Carbonyl and Thiocarbonyl Complexes.—For a comprehensive survey the reader should consult the Organometallic Specialist Periodical Report. 

Further thermodynamic data,10 absolute integrated intensities for the i.r. absorption bands,11 and more Raman data12 have been presented for Cr(CO)6. Core13 and valence region14 photoelectron spectra have been determined for Cr(CO)6 and discussed on the basis of MO data. Examination of the reaction products of Cr atoms with CO at 4.2—10K has established the existence of a Cr(CO)5 species having a D3h, trigonal-bipyramidal stereochemistry. The data obtained using pure 

Na2[Cr(CO)5] reacts with C12CS in THF to produce Cr(CO)5(CS) in ca. 5% yield. This thiocarbonyl complex reacts with Ph3P to produce trans-[Cr(CO)4-(CS)PPh3] and with primary amines (RNH2) to produce a thiocarbene, which 

Trifluorophosphino- and Trichlorostannano-complexes.- The photoelectron spectrum of Cr(PF3)6 has been determined and compared with other available data for transition-metal trifluorophosphino- and carbonyl-complexes.32 

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Stable thiocarbonyl complexes containing the elusive CS ligand are also now well established and known coordination modes, which include terminal, bridging and polyhaplo, are as shown at the top of the next column/ ... 

The complex also undergoes a variety of addition reactions with reagents such as methyl iodide, hydrochloric acid, benzoyl chloride, and allyl chloride.8 In a reaction similar to that of the decarboxylation of aldehydes, the complex will abstract CS from carbon disulfide to give the irans-thiocarbonyl complex rans-RhClCS[P(C8H6)5]2.9... 

Table 7.3 lists only few experimental data that can be used to estimate the accuracy of the theoretical results. The CCSD(T)/II values agree quite well with experiment (note, however, rather large error bars for the measured BDEs of the thiocarbonyl complexes). The MP2/II values are always larger than their CCSD(T)/n counterparts. The latter values show that the tungsten complexes always have the strongest M-Lbond while, in most cases, the molybdenum species have the lowest BDEs. 

The reductive behavior of iron-carbene porphyrins has been investigated. A 2g + FI" " reduction of thiocarbonyl complexes can lead to the corresponding thioformyl complexes in a reversible system [421]. 

Since the discovery of the first transition metal thiocarbonyl complexes by Baird and Wilkinson in 1966,1 over 100 of these complexes have been synthesized, encompassing essentially all the transition metals.2 3 X-Ray data4,5 reveal that... 

In a UPS study of thiocarbonyl complexes such as M(CO)sCS, M = Cr, W (202a) it was found that the ionizations associated with the o and it levels of coordinated CS are clearly separated from the other ionizations. It was concluded that CS is a better n acceptor than CO. 

The complexes are reactive towards nucleophilic as well as electrophilic attack. Attack by alkyl halides yields thioalkylated compounds. Mostly an alkylation at one sulfur atom takes place, but examples of alkylation at both sulfur atoms are known (reactions 1 and 2). The facile sulfur abstraction with PPh3 yielding a thiocarbonyl complex is a nucleophilic reaction (reaction 3). 

Carbonyl and thiocarbonyl complexes of Mes2Si have been observed in a remarkable series of experiments by Ando and coworkers144. Photolysis of Mes2Si(SiMe3)2 was carried out at 77 K in a soft (3-MP/isopentane) matrix in the presence of tetramethyl-2-indanone or its sulfur analog. The free silylene was formed initially but it slowly reacted with the carbonyl (or thiocarbonyl) compound to give the complex, which can be formulated as a silacarbonyl ylide (Scheme 8). Further photolysis converted these ylide complexes to the silaoxirane or silathiirane, reversibly. 

Unlike the parent carbonyl compound IrCl(CO)(PPh3)2 the thiocarbonyl complex forms 1 1 adducts with the aid of the acidic cyano olefins only. The stoichiometry of the adducts of IrCl(CO)(PPh3)2 and IrCl(CS)(PPh3)2 with BX3 (X = Cl, Br) has not been satisfactorily established143. 

In so far as the decrease in chemical reactivity is an indication of diminished transition metal basicity, it was proposed143 that the thiocarbonyl complex is less basic than its carbonyl analogue. This conclusion is substantiated by the spectral shifts in Table 22 and is also in agreement with molecular orbital calculations which predict the thiocarbonyl complex to be less basic than the carbonyl complex155,156. 

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