Reaction products of ammonium pertechnetate(VII) with triphenylphosphine and crystal structures of mer-Tc(PPh3)2Cl3(DMF) •2PPh3 and NH2(CH3)2+DMAH+ [TcCl6]2−•PPh3O

Abstract

The reaction of NH4TcO4 with PPh3 in DMF solution in the presence of HCl produces mer-Tciii(PPh3)2Cl3(DMF)•2PPh3 (1). When the reaction is done in acidic DMA, the yellow product isolated was identified as NH2(CH3)2+DMAH+ [TcCl6]2−•PPh3O (2). The dimethylammonium cation was produced from the reaction of the solvent (DMA) with aqueous HCl. The reaction of NH4TcO4 with PPh3 in acidic acetone solution produces yellow (PPh3H)2[TcCl6] (≈15% yield) and some orange crystals (≈65% yield) identified by X-ray diffraction as [Ph3P-C(CH3)2-CH2-CO-CH3]+ [Tc(PPh3)Cl5]−. The cation was produced from the reaction of acetone used as solvent with HCl and PPh3. The crystals of 1 are monoclinic with P21/m space group, a = 11.393(4), b = 24.993(11), c = 12.398(4) Å, β = 106.98(3)°, Z = 2. The structure was refined to R = 0.072 and wR = 0.058. The Tc—O bond distance is 2.115(12) Å while the Tc—P bond lengths are 2.496(5) and 2.499(5) Å and the Tc—Cl are 2.399(5) and 2.342(3) Å. The C atoms of the DMF ligand are disordered. The crystals of 2 are triclinic, [Formula: see text] space group with a = 8.627(5), b = 13.308(7), c = 14.401(9) Å, α = 97.62(5), β = 91.31(5), γ = 106.42(5)°, and Z = 2. The structure was refined to R = 0.060 and wR = 0.076. The proton on DMAH+ is hydrogen bonded to the oxygen of PPh3O with a distance [Formula: see text] Key words: technetium, DMF, triphenylphosphine, dimethylacetamide.