Thallium reaction with metal carbonyls

Thallium(i) salts have long been used in reactions with organic and organometallic halide complexes as a means of activating the halide by removal as insoluble T1X. However, the thallium ions proved not to be innocent bystanders, and numerous examples were reported in COMC (1995) where the metal-bound thallium complexes were formed. Deliberate reactions of thallium(i) and thallium(m) salts with metal carbonyl anions have yielded a variety of complexes of the form T1 MLJ3. In the past decade, new examples of metal carbonyl derivatives of thallium have been prepared (see Table 2). In addition, the propensity for Tl+ to form adducts with 16-electron noble metal complexes has been exploited. 

B. Reaction of a Thallium Metal Carbonylate with a Silicon Halide. .. 11... 

Thallium derivatives of transition-metal carbonyls are used to prepare compounds in which Sn is bonded to two different transition metals. Reaction conditions are mild—THF at RT for 0.25 h—and yields are good (80-90%). Reactions with -CpCr(CO)3Tl, which must be carried out in the dark, yield (CO)4CoSnCl2Mn(CO)4(PPh3), > -Cp(CO)3CrSnCl2Mn(CO)4(PPh3), (CO)4CoSnCl2Fe(CO)2Cp- / and i -Cp(CO)3CrSnCl2Fe(CO)2Cp-j/. ... 

The counterion used with the metal carbonyl anion is important. Thallium salts are preferable to sodium salts, in part because the former are often soluble in hydroearbon solvents in which disproportion of the metal-metal-bonded eomplex is a less serious problem e.g., reaction of Tl[Co(CO)4] with MnfCOlsBr in methylene chloride gives the mixed dimer (OC)4CoMn(CO)5. ... 

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