Synthesis, structure and reactivity with phosphines of Hg(ii)ortho-cyano-aminothiophenolate complexes formedviaC–S bond cleavage and dehydrogenation of 2-aminobenzothiazoles

Abstract

Addition of 2-aminobenzothiazole (abt) and substituted derivatives to Hg(OAc)2 leads to the high yield formation of ortho-cyano-aminothiophenolate (ocap) complexes [Hg{SC6H3XN(C≡N)}]n (X = H, Me, Cl, Br, NO2) resulting from dehydrogenation...

Palladium(ii) ortho-cyano-aminothiophenolate (ocap) complexes

“…The complex is heterobimetallic Pd(κ 2 -phen)(μ-κ 2 ,κ 1 -ocap)HgCl 2 (κ 2 -phen) (11), which co-crystallises with three molecules of CHCl 3 . The Pd(κ 2 -phen)(μ-κ 2 ,κ 1ocap) sub-unit is as expected and contains a square planar Pd (II) centre ligated by phenanthroline and ocap chelates with bite angles of 80.83 (17)…”

“…Nevertheless, these protons must still be acidic such that upon addition of base deprotonation results in activation leading to eventual C-N bond scission and ringopening, the mechanism of which has been probed at Hg(II). 17 Given the relative insolubility of coordination polymers 2a-b and our previous success in breaking down the analogous Hg (II) complexes 1a-b upon addition of phosphines, 16,17 we attempted to prepare mononuclear square planar complexes of the type Pd(κ 2 -ocap)(PPh 3 ) 2 via addition of 2 equivalents of PPh 3 to 2a-b in refluxing CHCl 3 . However, in no instance did we generate such mononuclear complexes, but rather dimeric [Pd(μ-κ 2 ,κ 1 -ocap)(PPh 3 )] 2 (4a-b) resulted, being isolated as redbrown crystalline solids in good yields (Scheme 3).…”

“…We recently reported the high yield synthesis of a series of Hg(II) ortho-cyano-aminothiophenolate (ocap) complexes, [Hg{SC 6 H 3 XN(CuN)}] n (1a-e) (Scheme 1) resulting from the simple addition of 2-aminobenzothiazole and substituted derivatives to mercuric acetate in warm EtOH. 16,17 These contain the previously unreported ocap ligand and result from loss of hydrogen and sulfur-carbon bond scission. While they have limited solubility in common organic solvents, addition of phosphines affords a series of soluble derivatives in which the ocap ligand was shown to be highly versatile, three different binding modes (A-C) being shown crystallographically, 16,17 while a fourth (D) was proposed for 1a-e (Chart 1).…”

“…16,17 These contain the previously unreported ocap ligand and result from loss of hydrogen and sulfur-carbon bond scission. While they have limited solubility in common organic solvents, addition of phosphines affords a series of soluble derivatives in which the ocap ligand was shown to be highly versatile, three different binding modes (A-C) being shown crystallographically, 16,17 while a fourth (D) was proposed for 1a-e (Chart 1).…”

“…Herein we provide details of the successful application of this strategy which allows access to Pd(II)-ocap complexes, which in analogy with the mercury complexes can adopt different binding modes. Stirring [Hg{SC 6 H 3 XN(CuN)}] n (1a-b) 16,17 with a slight excess of Na 2 S in a water-EtOH mixture for ca. 1 h resulted in formation of a black precipitate, assumed to be HgS.…”