Formation of ortho-cyano-aminothiophenolate ligands with versatile binding modes via facile carbon–sulfur bond cleavage of 2-aminobenzothiazoles at mercury(ii) centres

Abstract

Addition of 2-aminobenzothiazole and substituted derivatives to mercuric acetate in warm ethanol leads to the high yield formation of [Hg{SC6H3XN(C[triple bond, length as m-dash]N)}]n resulting from loss of hydrogen and sulfur-carbon bond cleavage. Addition of phosphines affords a series of complexes in which the new ortho-cyano-aminothiophenolate ligands adopt three different binding modes.

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

“…This is confirmed by the molecular structure of [Hg{SC 6 H 3 MeN(CN)}{Ph 2 P(CH 2 ) 4 PPh 2 }] n ( 9b ) (Fig. 6) 8 which is similar to that of 7a (Fig. 5), consisting of a 1D coordination polymer in which tetrahedral Hg( ii ) centres are linked by diphosphines.…”

“…3. 8 It is again a centrosymmetric dimer, but unlike 4a consists of a central Hg 2 S 2 core with each mercury centre also being coordinated to one phosphine and a nitrogen of an N-CuN moiety. Both Hg-S and Hg-N bond lengths are slightly shorter than those in 4a and the Hg-P distance is longer.…”

“…2. 8 It is a centrosymmetric dimer in which the coordination geometry at each Hg( ii ) centre is a distorted N 2 PS tetrahedron. The ortho -cyano-aminothiophenolate ligands adopts coordination mode B (Chart 2) chelating to one mercury [N1–Hg1–S1 81.76(11)°], while bridging to a second through coordination of cyanide.…”

“…A few years ago, we reported our preliminary observations of the serendipitous synthesis of ortho -cyano-aminothiophenolate (ocap) complexes of mercury via the ring-opening dehydrogenation of 2-aminobenzothiazole (abt) and some derivatives. 8 Herein we develop this chemistry, showing that a range of such ligands are readily accessible in a simple one-pot reaction, and these complexes react with phosphines to give complexes displaying varying coordination geometries of the ortho -cyano-aminothiophenolate ligand.…”

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

“…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).…”