Mercuriation of 3,4,5-trimethoxybenzoic acid. Synthesis of derivatives of the mercuriation product and crystal and molecular structure of PPh 3(CH 2Ph)][HgCl{C 6H(CO 2)-6-(OMe) 3-2,3,4}

Abstract

The mercuriation of 3,4,5-trimethoxybenzoic acid has been re-investigated and the product [HgCl{C 6H(CO 2H)-6-(OMe) 3-2,3,4}] ( 1) characterized. It is deprotonated by Na 2CO 3 to give [Hg{C 6H(CO 2)-6-(OMe) 3-2,3,4}] n ( 2) which, in turn, reacts with benzyltriphenylphosphonium chloride or triphenylphosphine to give [PPh 3(CH 2Ph)][HgCl{C 6H(CO 2)-6-(OMe) 3-2,3,4}]( 3) or [Hg{C 6H(CO 2)-6-(OMe) 3-2,3,4}(PPh 3)] ( 4), respectively. The reaction of 2 with MeI in the presence of [NMe 4]Cl affords [Hg{C 6H(CO 2Me)-6-(OMe) 3-2,3,4} 2] ( 5), which reacts with HgCl 2 or HgCl 2 to give [HgX{C 6H(CO 2Me)-6-(OMe) 3-2,3,4}] [X  Cl ( 6), I ( 7)]. The crystal structure of 3 shows a linear geometry at the mercury atom [ClHgC 178.0(2)°, HgCl 2.315(2), HgC 2.060(5) Å], with an additional long Hg⋯O contact [2.573(4) Å].