Hexakis(N-methylthiourea)technetium(III) hexafluorophosphate hydrate and hexakis(N,N'-dimethylthiourea)technetium(III) hexafluorophosphate

Abstract

Tc(C2H6NaS)6)(PF6)3.H20, Mr = 1092.70, triclinic, P1, a=6.754(3), b= 11.737(8), c= 13.217 (7) A, a=74.45(5), ,6=86.30(4), y= 86.39 (5) °, V = 1006 (1) A 3, Z = 1, Dx = 1.803, Dm = 182 Mg m -3, A(Mo Kte) = 071069 ,~, /x(Mo Kce) = 0-879 mm-~, F(000)= 548, room temperature, R = 0.059 for 3731 unique observed reflections. The cation is approximately octahedral and the methyl- thiourea ligands are S bonded. The Tc atom lies on an inversion centre with Tc--S distances = 2-419 (1), 2.451 (1) and 2.460 (1)/~. All the methylthiourea ligands have the cis configuration. One PF6 anion is also located on an inversion centre. Most of the F atoms show high thermal motion. The compound crystallizes with a disordered molecule of water. The structure is stabilized by hydrogen bonds. (Tc(CaH8N2S)6)(PF6)3, Mr = 1158.85, monoclinic, P21/c, a = 13.306 (13), b = 20.943 (15), c = 17.082 (13) A,/3 = 102.54 (7) °, V = 4646 (7) A 3, Z = 4, Dx = 1.656 Mg m -3, A(Mo Ktr) = 0.71069 ~, /z(Mo Kte) = 0.759 mm-l, F(000) = 2344, room tem- perature, R = 0.079 for 2961 unique observed reflec- tions. The cation is approximately octahedrally coordinated by the six S atoms of the dimethyl- thiourea ligands. The Tc--S distances are 2.426 (3), 2.451 (3), 2.430 (3), 2-436 (3), 2.460 (3) and 2.436 (3),~. All the dimethylthiourea ligands have the cis-trans configuration. The F atoms have high thermal motion. The structure is stabilized by intra- and intermolecular hydrogen bonds. Introduction. Thiourea derivatives are ligands of interest due to the presence of three potential donor sites, the S and the two N atoms. The binding site assigned by infrared data on several metal complexes has been controversial. But all crystal structure determinations have shown that the binding site is the S atom. Furthermore, the C--N bonds of thiourea derivatives have an appreciable double bond character. Therefore N-alkyl derivatives of thiourea can have different configurations where the thioamide H atom and the thiocarbonyl bonds are either cis or trans. For N-alkylthiourea, there are two isomers, cis and trans, whereas for N,N'-dialkyl- cis-c&