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.
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.
Rochon
Fernande D.
FD
Department of Chemistry, Université du Québec à Montréal, CP 8888, Succursale Centre-ville, Montréal, Canada H3C 3P8.
Melanson
Robert
R
Kong
Pi-Chang
PC