Preparation and molecular structure of trans-chlorobis(pentane-2,4-dionato)(triphenylphosphine)technetium(III)

Abstract

The title complex trans-[Tc(pd)₂(PPh₃)Cl], prepared by reaction of pentane-2,4-dione(pd) with trans-[Tc(PPh₃)₂Cl₄], crystallises in the centrosymmetric space group P with a= 13.152(8), b= 15.042(10), c= 15.532(13)Å, α= 112.26(11), β= 91.01(7), γ= 104.70(9)°, and Z= 4. Intensity measurements have been made with Mo-K_α radiation for the 6 601 independent reflections having 2θ⩽ 44° utilising the θ—2θ scan technique on a diffractometer. The structure has been solved by using the heavy-atom technique and has been refined using full-matrix least-squares procedures to a final R value of 0.063 using 4 950 independent reflections having I > 3σ(I). There are two crystallographically independent molecules which differ chiefly in the folding angles of the pd ligands about the O ⋯ O ‘bite’ axis. The octahedral co-ordination polyhedron is tetragonally elongated and approximates idealised D_4h symmetry. The four ‘short’ Tc–O bonds have an average length of 2.01(1)Å, while the two ‘long’trans Tc–Cl and Tc–P have lengths of 2.42(1) and 2.46(1)Å, respectively. The bonding scheme and trans conformation are discussed in terms of the angular-overlap molecular-orbital model.