Desulphurization of sulphur-containing organometallic compounds

Luminescent Platinum−Tin-Bonded Metallacycles: First Oxidative Addition of Sn−S Bonds

“…Diorganotin sulfides, which usually occur as the six-membered-ring compounds (R 2 SnS) 3 (e.g., R = Me, Et, Ph), show interesting organometallic reactivity and find applications in both catalytic and stoichiometric organic synthesis, but no oxidative-addition reactions with transition-metal complexes have been explored. This paper reports the first such reactions in which the unusual oxidative addition of two R 2 SnS units from (R 2 SnS) 3 (R = Me, Ph) to [PtMe 2 ( t bu 2 bpy)] 3 ( t bu 2 bpy = 4,4‘-di- tert- butyl-2,2‘-bipyridine) yields the luminescent organoplatinum(IV) complexes [PtMe 2 (R 2 SnS) 2 ( t bu 2 bpy)] ( 1 and 2 ) (Scheme ), containing the new five-membered PtSnSSnS ring.…”

“…It is reasonable to predict that the oxidative addition with Sn−S bond cleavage of the diorganotin sulfides to [PtMe 2 ( t bu 2 bpy)] to give 1 and 2 proceeds by a polar S N 2 mechanism, as described elsewhere for the oxidative addition of organotin halides to related organoplatinum(II) complexes. , However, the way in which only two of the three R 2 SnS units of (R 2 SnS) 3 are incorporated remains uncertain. It is known that redistribution of R 2 SnS units occurs easily in the trimers (R 2 SnS) 3 ; the mechanism is probably associative, perhaps with a “ladder” intermediate, though the detailed mechanism is difficult to establish 1a. Clearly, the redistribution reactions observed for the five-membered PtSnSSnS ring compounds could occur in a similar way, but it is also possible that they could occur by reductive elimination of the diorganotin sulfide fragment, as established above, followed by scrambling within the diorganotin sulfide oligomers and then oxidative addition to re-form a new PtSnSSnS ring.…”

“…The selectivity for formation of the unsymmetrical 3 rather than its isomer containing a Pt(SnPh 2 )S(SnMe 2 )S ring is remarkable. Complex 3 must be the product of thermodynamic control, since it is formed selectively by three different routes, but molecular mechanics calculations indicate that steric energies are similar for the two isomers, and most redistribution reactions in organometallic chemistry lead to all possible isomers (see for example ref a).…”

“…In conclusion, the first Sn−S bond oxidative additions lead to interesting new five-membered PtSnSSnS metallacycles which display unusual reactivity and luminescence properties. The ease of formation of the metallacycles, coupled with the known reactivity of Pt−Sn bonds, suggests that transition-metal catalysis could widen the scope of the use of (R 2 SnS) 3 in organic synthesis. ,, …”