Synthesis of Mercury(II) and Palladium(II) Organometallic Derivatives of Terephthaldehyde by Metalation, Transmetalation, Oxidation, and Condensation Reactions. X-ray Crystal Structures of trans-[PdCl{C6H3(CO2H)2-2,5}(PPh3)2]·Me2CO·2MeOH, trans-[PdCl{C6H3(CHO)-2-(CO2H)-5}(PPh3)2]·2CH2Cl2, and [Pd{C6H3(CHNC6H4NH2-4)-2-(CHO)-5}(N,N,N‘,N‘-Tetramethylethylenediamine)]CF3SO3. Molecular Assemblies through [Pd]−Cl···HO2C−Aryl and [Pd]−Cl···HOMe HO(O)C−Aryl Hydrogen Bonds

Abstract

The organomercurials [HgCl{C6H3(CHO)2-2,5}] (1) and [Hg{C6H3(CHO)2-2,5}2] (2) have been prepared by mercuriation of terephthaldehyde. Palladium complexes [PdCl{C6H3(CHO)2-2,5}(N-N)] (N-N = N,N,N‘,N‘-tetramethylethylenediamine (tmeda) (3) or 2,2‘-bipyridine (bpy) (3‘)) or trans-[PdCl{C6H3(CHO)2-2,5}(PPh3)2]·H2O (4) have been obtained by reacting (Me4N)2[Pd2Cl6] or trans-[PdCl2(PPh3)2], respectively, with 1 or 2. The reaction of potassium permanganate with complexes 3 and 3‘ or mercurial 1 results in the selective oxidation of the 5-formyl substituent affording [PdCl{C6H3(CHO)-2-(CO2H)-5}(N-N)] (N-N = tmeda (5), bpy (5‘)) or, respectively, a mixture whose major component is the fully oxidized [HgCl{C6H3(CO2H)2-2,5}] (7) or a mixture of isomers [HgCl{C6H3(CHO)-2-(CO2H)-5}]/[HgCl{C6H3(CO2H)-2-(CHO)}] (8a/8b) depending on the molar ratio of the reagents. The reaction of mixtures containing 7 or 8 with trans-[PdCl2(PPh3)2] give pure trans-[PdCl{C6H3(CO2H)2-2,5}(PPh3)2] (9) or trans-[PdCl{C6H3(CHO)-2-(CO2H)-5}(PPh3)2] (10), respectively. Complexes 3 and 3‘ react with amines and NaClO4·H2O or Tl(CF3SO3) to give, depending of the reaction conditions, cyclopalladated The mercurial 1 reacts with hydroxylamine to give the mercuriated oxime [HgCl{C6H3(CHNOH)2-2,5}] (14), which reacts with (Me4N)2[Pd2Cl6] to give the cyclopalladated From 15 some derivatives have been prepared. Complex 3 reacts with NH2OMe to give The imine C6H4(CHNTo)2-1,4 (To = C6H4Me-4) reacts with palladium(II) acetate to give the dipalladated Hydrolysis of 20 in the presence of potassium bromide and bpy results in the formation of [C6H2{PdBr(bpy)}2-1,4-(CHO)2-2,5] (21), from which [C6H2{Pd(PPh3)(bpy)}2-1,4-(CHO)2-2,5](CF3SO3)2 (22) can be prepared. The structures of 9·Me2CO·1.5MeOH, 10·2CH2Cl2 (R = C6H4NH2-4) (12c‘) have been determined by X-ray crystallography.