The synthesis and reactivity of titanium diphenyl hydrazido(2−) complexes supported by the diamido-ether ligands O(2-C6H4NSiMe3)2 (N2 ArO) and O(CH2CH2NSiMe3)2 (N2O) are described. Reaction of Li2N2 ArO or Li2N2O with Ti(NNPh2)Cl2(py)3 afforded Ti(N2 ArO)(NNPh2)(py)2 (14) or Ti(N2O)(NNPh2)(py)2 (15) with κ3-mer-bound diamido-ether ligands. Reaction with tBu-bipy (4,4′-di-tert-butyl-2,2′-bipyridyl) or bipy (2,2′-bipyridyl) gave a switch to κ3-fac-coordination. Reaction of 15 with Ar′NCO (Ar′ = 2,6-C6H3 iPr2) gave Ti{O(CH2CH2NSiMe3)­(CH2CH2NC(O)N(SiMe3)Ar′)}-{N(NPh2)C(O)N(Ar′)}, in which the substrate has inserted into a Ti–Namide bond of N2O as well as adding to the TiNα multiple bond. With Ar′NCS the [2+2] cycloaddition product Ti(N2O){N(NPh2)C(NAr′)S}(py) was obtained, and with Ar′NCSe a mixture was formed including Ti2(N2O)2(μ-Se)2. Both 14 and 15 reacted with ArFxCN (ArFx = C6H3F2 or C6F5) to give TiNα bond insertion products of the type Ti(L){NC(ArFx)NNPh2}(py)2 (L = N2 ArO or N2O) containing hydrazonamide ligands. Reaction of 14 with XylNC (Xyl = 2,6-C6H3Me2) gave only the isonitrile σ-adduct Ti(N2 ArO)(NNPh2)(py)(CNXyl), whereas 15 underwent Nα–Nβ bond reductive cleavage with tBuNC or XylNC forming Ti(N2O)(NPh2)(NCNtBu) or Ti{O(CH2CH2NSiMe3)­(CH2CH2NCN­(SiMe3)Xyl)}­(NPh2)(NCNXyl) (27). Both contain metalated carbodiimide ligands, but in 27 an additional reaction of XylNC with the Ti–Namide bond of N2O has taken place. Compound 15 also reacted with a number of internal alkynes RCCR′ (R = R′ = Me or Ph; R = Me, R′ = aryl) to give Nα–Nβ bond reductive cleavage products of the type Ti{O(CH2CH2NSiMe3)­(CH2CH2NC(R)­C(R′)­NSiMe3}(NPh2), again involving a reaction of a Ti–Namide bond.

Herein we report the preparation of a series of Ru(II) complexes featuring α‐iminopyridine ligands bearing thioether functionality (NNSR, where R = Me, CH2Ph, Ph). Metallation using [(p‐cymene)RuCl]2 permits access to Ru complexes with a κ2‐N,N donor set in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p‐cymene moiety is displaced, and the ligand adopts a κ3‐N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNSMe)Ru (NCMe)2Cl]Cl. The κ2‐N,N‐Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec‐phenethyl alcohol at modest loadings (alcohol: Ru = 20:1), using a variety of external oxidants and solvents. The complex bearing an S‐Ph donor was found to be the most active oxidation catalyst of those surveyed, suggesting that the thioether donor plays an active role in the catalytic cycle.

Herein we report the preparation of a series of Ru(II) complexes featuring alpha-iminopyridine ligands bearing thioether functionality (NNS^R, where R = Me, CH₂Ph, Ph). Metallation using (<i>p</i> cymene)RuCl dimer permits access to (k²-N,N)Ru complexes in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a k³-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNS^Me)Ru(NCMe)₂Cl]Cl. The k²-N,N Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at 5 mol% loadings, using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active of those surveyed, suggesting that the thioether donor plays an active role in catalyst speciation for this transformation.

Herein we report the preparation of a series of Ru(II) complexes featuring alpha-iminopyridine ligands bearing thioether functionality (NNS^R, where R = Me, CH₂Ph, Ph). Metallation using (<i>p</i> cymene)RuCl dimer permits access to (k²-N,N)Ru complexes in which the thioether moiety remains uncoordinated. In the presence of a strong field ligand such as acetonitrile or triphenylphosphine, the p-cymene moiety is displaced, and the ligand adopts a k³-N,N,S binding mode. These complexes are characterized using a combination of solution and solid state methods, including the crystal structure of [(NNS^Me)Ru(NCMe)₂Cl]Cl. The k²-N,N Ru(II) complexes are shown to serve as efficient precatalysts for the oxidation of sec-phenethyl alcohol at 5 mol% loadings, using a variety of external oxidants and solvents. The complex bearing an S-Ph donor was found to be the most active of those surveyed, suggesting that the thioether donor plays an active role in catalyst speciation for this transformation.