Synthesis and Characterization of Triazenide and Triazene Complexes of Ruthenium and Osmium

Triazenide [M(η2-1,3-ArNNNAr)P4]BPh4 [M = Ru, Os; Ar = Ph, p-tolyl; P = P(OMe)3, P(OEt)3, PPh(OEt)2] complexes were prepared by allowing triflate [M(κ2-OTf)P4]OTf species to react first with 1,3-ArN=NN(H)Ar triazene and then with an excess of triethylamine. Alternatively, ruthenium triazenide [Ru(η2-1,3-ArNNNAr)P4]BPh4 derivatives were obtained by reacting hydride [RuH(η2-H2)P4]+ and RuH(κ1-OTf)P4 compounds with 1,3-diaryltriazene. The complexes were characterized by spectroscopy and X-ray crystallography of the [Ru(η2-1,3- PhNNNPh){P(OEt)3}4]BPh4 derivative. Hydride triazene [OsH(η1-1,3-ArN=NN(H)Ar)P4]BPh4 [P = P(OEt)3, PPh(OEt)2; Ar = Ph, p-tolyl] and [RuH{η1-1,3-p-tolyl-N=NN(H)-p-tolyl} {PPh(OEt)2}4]BPh4 derivatives were prepared by allowing κ1-triflate MH(κ1-OTf)P4 to react with 1,3-diaryltriazene. The [Os(κ1-OTf){η1-1,3-PhN=NN(H)Ph}{P(OEt)3}4]BPh4 intermediate was also obtained. Variable-temperature NMR studies were carried out using 15N-labeled triazene complexes prepared from the 1,3-Ph15N=N15N(H)Ph ligand. Osmium dihydrogen [OsH(η2-H2)P4]BPh4 complexes [P = P(OEt)3, PPh(OEt)2] react with 1,3-ArN=NN(H)Ar triazene to give the hydride−diazene [OsH(ArN=NH)P4]BPh4 derivatives. The X-ray crystal structure determination of the [OsH(PhN=NH){PPh(OEt)2}4]BPh4 complex is reported. A reaction path to explain the formation of the diazene complexes is also reported.