Unidentate sulphur-bonded monothio-β-diketone complexes of chromium(0), molybdenum(0), and tungsten(0) and their protonation. The X-ray structure analysis of tetraethylammonium pentacarbonyl[1,1,1-trifluoro-4-(2-thienyl)-4-thioxobutan-2-onato-S]tungstate(0)

Abstract

The syntheses of the tetraethylammonium salts of the complex anions [M(CO)₅L]^–[M = Cr, MO, or W; L = mono-β-diketonate anions RCSCHOCR′(R = CF₃, or thienyl, R′= CF₃); R = Me, R′= CF₃, Me, or Ph; R = R' = Ph)] are reported. Hydrogen-I n.m.r. and i.r. data show that the monothio-β-diketonate ligand is unidentate and co-ordinated through the sulphur atom. A single-crystal X-ray structure analysis has shown that in the title complex the S-bonded unidentate ligand is present in a hitherto unobserved trans configuration. The complex crystallises in space group C222₁ with a= 8.818(5), b= 18.615(10), and c= 31.992(18)Å. Block-diagonal least-squares refinement of 2 559 reflections collected with a four-circle diffractometer has converged to R 0.038. The W–S bond length is 2.543(2)Å. Protonation of the [M(CO)₅L]^– species gives a series of highly unstable neutral complexes [M(CO)₅(HL)]. Hydrogen-1 n.m.r. and i.r. data show that in these complexes the S-bonded unidentate ligand is in a cis conformation similar to that of the free protonated ligand.