Two New Tripodal Ligands with an N4S3 Donor Set. The X-Ray Crystal Structure of 4,4′,4′′- [Nitrilotris(ethyleneimino)]tris(pent-3-ene-2-thione).

Abstract

Two new compounds with a tripodal ligand architecture and with the potential to act as heptadentate N₄S₃ donor ligands are reported. H₃S₃trac (4,4′,4′′-[nitrilotris(ethyleneimino)]tris(pent-3-ene-2-thione)) is prepared by the reaction of acetylacetone with tren (tris(2-aminoethyl)amine), followed by treatment with P₂S₅. H₃trimda (3,3′,3′′-[nitrilotris(ethyleneimino)]tris(2-phenylpropenethial)) is prepared by the reaction of 4-phenyl-1,2-dithiolium perchlorate with tren. A crystal structure of H₃S₃trac shows it to be monoclinic, P 2₁/c, a 11·443(7), b 11·7757(14), c 19·285(3) Å, β 106·68(2)°, Z 4, R 0·0454, ωR₂ 0·1108 for 1618 observed reflections (I > 3σ(I)). ¹H and ¹³C { ¹H} n.m.r. data for H₃S₃trac and H₃trimda, and the crystal structure of H₃S₃trac are consistent with the compounds existing in the enamino thione tautomer.