The synthesis, characterization and substitution reactions of the mixed ligand technetium(I) nitrosyl complex trans—trans-[(NO)(NCCH3)Cl2(PPh3)2Tc

Abstract

The techneium—nitrosyl complex n-Bu4N[Tc(NO)Cl4] reacts with excess triphenylphospine in refluxing acenotonitrile to give the Tc(I) mixed ligand complex [Tc(NO)Cl2(PPh3)2NCCH3 in good yield. The IR spectrum of this complex displays an absorption at 1690 cm−1 which is associated with v(NO). The FAB(+) mass spectrum shows the fragment of 723 mz which corresponds to [Tc(NO)Cl2(PPh3)2]+ which is generated from the loss of the acetonitrile ligand. The 1HNMRR spectrum of this species displays equivalent trans-triphenylphosphine ligands; however because of the liability of the acetnitrile ligand, two signals are observed from the coordinated and dissociated acetonitrile protons. The analogous reaction in the methanol gives the methanol adduct [Tc(NO)Cl2(PPh3)2HOCH3]. When pyridine is employed as solvent, the tris-pyridine complex [Tc(NO)Cl2(py)3] is isolated as the major product, with no phosphine coordination. The IR spectrum of this complex shows an absorption at 1688 cm−1 which is associated with v(NO). The FAB(+) mass spectrum shows the fragment of 436 m/z which corresponds to the parent ion [Tc(NO)Cl2(py)3]+. This diamagnetic Tc(I) complex displays a well resolved, narrow-lined 1H NMR spectrum. Crystal data for [Tc(NO)Cl2(py)3]∗d2CH3CN: monoclinic space group C2/c, (No. 15), a = 19.182(1), b = 10.8725(8), c = 11.9371(8) A, β = 116.580(7)°,V = 2226.5(6) A3, with Dcalc = 1.543 g cm−3 to give Z = 4. structure solution based on 2689 reflections converged at R = 0.025, Rw = 0.030, GOF = 1.41. The reaction chemistry of the acetonitrile adduct [Tc(NO)Cl2(PPh3)2NCCH3] with pyridine, 3,5-lutidine, bipyridine, phenanthroline and terpyridine is also presented.