Synthesis and Crystal Structure of a New Type of Ionic Technetium(V) Dioxo Phosphine Complexes, [Tc(O)(2)(PR(3))(3)](+). Reactions with Pyridine and Crystal Structures of trans,cis,cis-[Tc(O)(2)(PR(3))(2)(py)(2)](+) Compounds.

Abstract

New ionic technetium complexes of the type [TcO(2)(PR(3))(3)](+) have been synthesized from the reaction of [TcO(4)](-) with the phosphine in methanol. The crystal structures of two crystallographic forms of [TcO(2)(PEt(3))(3)](BPh(4)) were determined. The first form is monoclinic, space group P2(1)/n with a = 14.353(3) Å, b = 11.731(2) Å, c = 26.478(6) Å, beta = 101.22(1) degrees, and Z = 4. The second form is also monoclinic, space group P2(1)/c with a = 10.043(3) Å, b = 21.122(4), c = 20.994(5) Å, beta = 97.43(2) degrees, and Z = 4. [TcO(2)(PPr(3))(3)](BPh(4)) belongs to the monoclinic C2/c space group with a = 34.097(7) Å, b = 16.944(4) Å, c = 19.033(4) Å, beta = 102.99(1) degrees, and Z = 8. The geometry around the Tc atom is a trigonal bipyramid with the two oxo ligands in the trigonal plane. The Tc-O bond distances are between 1.707(4) and 1.726(3) Å, while the Tc-P bonds vary from 2.507(2) to 2.528(2) Å for the axial ligands and between 2.395(1) and 2.403(1) Å for the equatorial bond. The O-Tc-O angles are in the range 141.5(2)-143.4(2) degrees. The reaction of these complexes with pyridine produced trans,cis, cis-[Tc(O)(2)(PR(3))(2)(py)(2)](+) (py = pyridine). [Tc(O)(2)(PMe(3))(2)(py)(2)](BPh(4)) is monoclinic, space group P2(1)/c with a = 30.346(8) Å, b = 12.865(4) Å, c = 21.464(9) Å, beta = 110.35(2) degrees, and Z = 8, while [Tc(O)(2)(PEt(3))(2)(py)(2)](BPh(4)) is monoclinic, space group P2(1)/c with a = 10.594(6) Å, b = 19.921(7) Å, c = 21.306(10) Å, beta = 95.31(5) degrees, and Z = 4. The geometry around the Tc atom is a distorted octahedron with the oxo ligands located in trans positions to each other, while the phosphine and the pyridine ligands are cis to each other.