REGIOSELECTIVE ADDITION OF CHALCOGENOL TO AN ETA(3)-PROPARGYL ALLENYLCOMPLEX VIA FORMATION OF THE CARBON-CHALCOGEN BOND LEADING TO NEW CHALCOGENOXYALLYL SPECIES/

Regioselective addition of chalcogenol to an eta(3)-propargl complex [ Pt(PPh(3))(3)(eta(3)-C3H3)](BF4) (2) via the formation of the C-O, C-S , or C-Se bond generates new cationic chalcogenoxyallyl species {Pt(PP h(3))(2)[eta(3)-CH2C(ER)CH2]}(BF4) (E = O, R = Me (4a), Et (4b), Pr-i (4c), (t)Bu (4d), Ph (4e); E = S, R = Et (5b), Pr-i (5c), (t)Bu (5d), Ph (5e); E = Se, R = Ph (6e)) respectively in good yields. Thiol and s elenol react with complex 2 much faster than alcohol; and 2 reacts wit h p-(HO)C6H4(SH) to exclusively yield the thioxyallyl product {Pt(PPh( 3))(2)[eta(3)-CH2C(SC6H4OH)CH2]}(BF4) (5f). Among the alcohols and phe nol, the reactivity follows the order MeOH> EtOH>(PrOH)-Pr-i>(t)BuOH>P hOH. A mechanism comprising a preceding coordination step is postulate d. The X-ray structures of 4b, 4e, 5b, 5e and 6e are provided.