New entries to the [Ru(Cp/Cp*)(P R 2 N R' 2 )(MeCN)]PF 6 catalyst family were synthesized, including a Cp complex (R=Cy; R'=Ph) and two Cp* complexes (R=Cy, Ph; R'=Ph). These and other derivatives were used for the intramolecular hydroamination of 2-ethynylaniline to elucidate trends in catalytic lifetime and rate. The readily accessible [Ru(Cp)(P Cy 2 N Ph 2 )(MeCN)]PF 6 derivative showed comparable lifetime to [Ru(Cp)(P tÀ Bu 2 N Ph 2 )(MeCN)] PF 6 , the previous optimal catalyst. Donor-free 'active' catalysts, [Ru(Cp/Cp*)(P Cy 2 N Ph 2 )]PF 6 , were prepared and their thermal stability was assessed. The relatively high stability of the Cp derivative was explained by the capacity of the P Cy 2 N Ph 2 ligand to coordinate in a k 3 -(P,P,Ar) mode, which protects the lowcoordinate species. This coordination mode is inaccessible with the Cp* derivative. Additionally, [Ru(Cp*)(P Cy 2 N Ph 2 )]PF 6 readily activated the CÀ Cl bond of the solvent dichloromethane. Variable time normalization analysis (VTNA) revealed that the indole product inhibited the catalyst [Ru(Cp)(P Cy 2 N Ph 2 )(MeCN)] PF 6 , which slowed catalytic rates.

A family of [CpRu(PP)(MeCN)]PF6 complexes (2 a–e and 4) were prepared in which the bis‐phosphine ligand contains a pendent tertiary amine in the second‐coordination sphere. 2 a–e contain PPh2NR′2 ligands with two amine groups as the pendent base. Complex 4 has the PPh2NPh1 ligand with only one pendent amine. The catalytic performance of 2 a–e and 4 were assessed in the cyclization of 2‐ethynyl aniline and 2‐ethynylbenzyl alcohol. It was revealed that the positioning of the pendent amine near the metal active site is essential for high catalyst performance. A comparison of PPh2NR′2 catalysts (2 a–e) showed minimal difference in performance as a function of pendent amine basicity. Rather, only a threshold basicity – in which the pendent amine was more basic than the substrate – was required for high performance.

Methacrylated lignin was reacted with PH3(g) to prepare a phosphorus rich bio-based polymer containing PH/PH2 functional groups, which were converted to tertiary phosphine units via the phosphane-ene reaction. This represents...

The cooperative [Ru(Cp)(P 2 Cy N 2 Ph )(MeCN)][PF 6 ] (Ru2) complex was utilized for additive-free hydroalkoxylation of 2-ethynylbenzyl alcohol (1a) to generate isochromene. The phenyl-substituted pendent amine of the supporting ligand effectively mediated proton-transfer steps and mitigated a vinyl ammonium deactivation pathway that was previously favored with a more nucleophilic N-benzyl substituent. A select set of substrates were cyclized to uncover mechanistic opportunities and limitations of Ru2 and related catalysts. Isotopic labeling and kinetic studies, using the variable time normalization analysis (VTNA) method, were utilized to identify vinylidene formation as the most likely rate-limiting step of catalysis. Attempted cyclization of 3-butyn-1-ol afforded an isolable alkoxycarbene complex, the stability of which was investigated both computationally and through stoichiometric reactions. This compound is identified as an off-cycle catalytic species, and it reveals a critical competing proton-transfer pathway for this family of cooperative catalysts.