Synthesis, structure, and reactivity of ruthenium and osmium nitrido complexes with 1,2-benzenedithiolate ligands: N- versus S-alkylation

The reactivity of the nitrido complexes (N(n)Bu(4))[Ru(N)(S2C6H4)(2)] (1) and ((NBU4)-B-n)[Os(N)(S2C6H4)(2)] (2) (C6H4(SH)(2) = 1,2-benzenedithiol) toward electrophiles, R(+) (R = Me, Et, Ph(3)C), is described. While 1 yielded intractable mixtures of products, 2 could be cleanly alkylated. The synthesis of 1 has been reported previously (Z. Naturforsch. 1987, 42B, 341); complex 2 can be synthesized by treating (N(n)Bu(4))[Os(N)Cl-4] with deprotonated 1,2-benzenedithiol in acetone/MeOH at 0 degrees C. Complexes 1 and 2 are isostructural and crystallize in the orthorhombic space group Pna2(1), Z = 8, with a = 36.881(6) Angstrom, b = 9.402(2) Angstrom and c = 17.652(2) Angstrom for 1 and a = 37.042(4) Angstrom, b = 9.375(2) Angstrom, and c = 17.671(2) Angstrom for 2. The anions of both compounds consist of a five-coordinate mononuclear center with a distorted square-pyramidal geometry; a terminal nitrido Ligand occupies the apical position and two chelating (S2C6H4)(2-) ligands form the basal plane. Treatment of 2 with R(3)OBF(4) in CH2Cl2 yields [Os(N)(S2C6H4)(SC(6)H(4)SR)] (R = Me, 3; R = Et, 4) where one thiolate donor is alkylated. Alkylation of the sulfur of the 1,2-benzenedithiolate ligand was confirmed by NMR spectroscopy and X-ray crystallography (for 3). Complex 3 . CH2Cl2 crystallizes in the orthorhombic space group P2(1)2(1)2(1), Z = 4, With a = 8.551(1) Angstrom, b = 10.772(2) Angstrom, and c = 19.716(3) Angstrom. In contrast, treatment of 2 with Ph(3)CPF(6) in CH2Cl2 yields [Os(NCPh(3))(S2C6H4)(2)] (5), whose H-1 and C-13 NMR spectra indicate that the terminal nitride is the site of electrophilic attack. X-ray crystallography further confirms the alkylation at the nitrogen atom; complex 5 crystallizes in the triclinic space group P1, Z = 2, with a = 9.338(8) Angstrom, b = 10.001(3) Angstrom, c = 16.280(6) Angstrom, alpha = 75.88(3)degrees, beta = 74.29(6)degrees, and gamma = 69.55(5)degrees.