Reactions of co-ordinated ligands. Part 16. The oxidative–addition of hexafluorobut-2-yne and 3,3,3-trifluoroprop-1-yne to tricarbonyl(1,3- diene)-iron and -ruthenium and tricarbonyl(diphenyl-o-styrylphosphine)-iron complexes: crystal and molecular structure of [Ru(CO)2{P(OCH2)3CMe}(C6H8)(C4F6)2]

Abstract

Hexafluorobut-2-yne (hfb) reacts (u.v.) with buta-1,3-diene(tricarbonyl)iron, tricarbonyl(2.3-dimethylbuta-1.3- diene)iron, or tricarbonyl(diphenyl-o-styrylphosphine) iron to form Fe^II 1 : 1 adducts in which the acetylene links the iron and dienes as in, for example, CH₂[graphic omitted](CO)₃. Similar reactions with 3,3,3-trifluoroprop-1-yne gave the corresponding adducts, in which the arrangement FeC(CF₃)CH– is present. In contrast tricarbonyl(cyclohexa-1,3-diene)ruthenium forms on irradiation with hfb a 1 : 2 adduct. Replacement of co-ordinated CO in the adduct by P(OCH₂)₃CMe gave crystals of (9)[Ru(CO)₂{P(OCH₂)₃CMe}(C₆H₈)(C₄F₆)₂] suitable for X-ray crystallography. Crystals of (9) are monoclinic, space group P2₁/c, with Z= 4 in a unit cell of drmensions: a= 8.875(5), b= 17.841 (9), c= 16.517(5)Å, β= 94.51(3)°. The X-ray diffraction study (R 0.078, 2 418 observed intensities, measured by diffractometer) shows that formal insertion of a hfb molecule has occurred between the Ru atom and each carbon atom of one of the original olefinic bonds of the cyclohexadiene system. A new seven-membered ruthenacyclohepta-1,5-diene ring is generated. The co-ordination state of the Ru atom is close to octahedral, the ring system occupying three facial sites.

Reaction of CH₂[graphic omitted](CO)₃ with carbon monoxide affords an acyl species; however, with heat in the absence of CO an interesting reductive–elimination reaction occurs with formation of a substituted tricarbonyl(cyclohexa-1,3-diene)iron complex. A similar ring closure reaction occurs with the adduct from [Fe(1,3-C₄H₆)(CO)₃] and hfb.