Crystal structures of(AsPh 4)[TcO(SCOCOS) 2] and (AsPh 4) 2[TcN(SCOCOS) 2]. A comparison of the Tc VO 3+ and Tc VN 2+ cores in the same coordination environment

Abstract

The reaction of potassium dithiooxalate in acetone with (AsPh 4)[TcNCl 4] in acetonitrile yields crystals of (AsPh 4) 2[TcN(SCOCOS) 2] ( 1). We now report the X-ray structures of 1 and the oxo analogue (AsPh 4)[TcO(SCOCOS) 2] ( 2), both of which contain the technetium atom in the +5 oxidation state and in the same coordination environment. Crystals of 1 and 2 belong to the triclinic space group P 1 with Z=2. Unit cell parameters are: 1, a=14.225(5), b=17.778(2), c=10.993(3) Å, α=101.52(2), β= 111.74(2), γ=100.68(2)° and 2, a=12.294(2), b=12.531(2), c=13.071(2) Å, α=115.10(1), β= 114.22(1), γ=101.93(1)°. Refinement with data measured with Cu Kα radiation converged at R= 0.055 for 7569 observed data 1 and at R=0.041 for 4739 observed data 2. The technetium atoms in the complex anions are five-coordinate with the four sulphur atoms in the basal position and either the oxygen or nitrogen in the apical position, to give a distorted square-pyramidal environment about each technetium. The TcO and TcN bond lengths are 1.646(4) and 1.613(4) Å in 1 and 2 respectively.