Chelating Assistance of P–C and P–H Bond Activation at Palladium and Nickel: Straightforward Access to Diverse Pincer Complexes from a Diphosphine–Phosphine Oxide

The diphosphine–phosphine oxide (DPPO) {[<i>o</i>-<i>i</i>-Pr₂P-(C₆H₄)]₂P­(O)­Ph} (<b>1</b>) reacts with [Ni­(cod)₂] (cod = 1,4-cyclooctadiene) to give the diphosphine–phosphide oxide κ^P,P(O),P pincer complex <b>3</b>. According to DFT calculations, the Ph–P­(O) bond activation involves a three-center P,C_ipso,Ni transition state. Reaction of the DPPO ligand <b>1</b> with [(nbd)­Pd­(ma)] (nbd = 2,5-norbornadiene and ma = maleic anhydride) affords the [(DPPO)­Pd­(ma)] complex <b>4</b>. Upon heating, the ma coligand is displaced and the κ^P,P(O),P palladium pincer complex <b>2</b> is obtained. The dinuclear complex {(DPPO)­[Pd­(ma)]₂} (<b>6</b>) has also been authenticated. X-ray diffraction analysis showed an original situation in which the oxygen atom of the central phosphine oxide moiety bridges the two palladium centers. Addition of trifluoromethanesulfonic acid to DPPO <b>1</b> affords the trifunctional phosphine–phosphine oxide–phosphonium derivative <b>7</b>. Upon reaction with [Pd₂(dba)₃], the palladium hydride κ^P,O(P),P pincer complex <b>8</b> is cleanly formed as the result of P⁺–H bond activation. Complex <b>8</b> is readily deprotonated by DBU (DBU = 1,8-diazabicycloundec-7-ene), and spontaneous oxidative addition of the Ph–P­(O) bond gives the diphosphine–phosphide oxide κ^P,P(O),P pincer complex <b>2</b>. Conversely, addition of trifluoromethanesulfonic acid on <b>2</b> does not give back the palladium hydride <b>8</b> but leads to the diphosphine–hydroxy phosphine κ^P,P(OH),P pincer complex <b>9</b>

Chelating Assistance of P–C and P–H Bond Activation at Palladium and Nickel: Straightforward Access to Diverse Pincer Complexes from a Diphosphine–Phosphine Oxide

The diphosphine–phosphine oxide (DPPO) {[<i>o</i>-<i>i</i>-Pr₂P-(C₆H₄)]₂P­(O)­Ph} (<b>1</b>) reacts with [Ni­(cod)₂] (cod = 1,4-cyclooctadiene) to give the diphosphine–phosphide oxide κ^P,P(O),P pincer complex <b>3</b>. According to DFT calculations, the Ph–P­(O) bond activation involves a three-center P,C_ipso,Ni transition state. Reaction of the DPPO ligand <b>1</b> with [(nbd)­Pd­(ma)] (nbd = 2,5-norbornadiene and ma = maleic anhydride) affords the [(DPPO)­Pd­(ma)] complex <b>4</b>. Upon heating, the ma coligand is displaced and the κ^P,P(O),P palladium pincer complex <b>2</b> is obtained. The dinuclear complex {(DPPO)­[Pd­(ma)]₂} (<b>6</b>) has also been authenticated. X-ray diffraction analysis showed an original situation in which the oxygen atom of the central phosphine oxide moiety bridges the two palladium centers. Addition of trifluoromethanesulfonic acid to DPPO <b>1</b> affords the trifunctional phosphine–phosphine oxide–phosphonium derivative <b>7</b>. Upon reaction with [Pd₂(dba)₃], the palladium hydride κ^P,O(P),P pincer complex <b>8</b> is cleanly formed as the result of P⁺–H bond activation. Complex <b>8</b> is readily deprotonated by DBU (DBU = 1,8-diazabicycloundec-7-ene), and spontaneous oxidative addition of the Ph–P­(O) bond gives the diphosphine–phosphide oxide κ^P,P(O),P pincer complex <b>2</b>. Conversely, addition of trifluoromethanesulfonic acid on <b>2</b> does not give back the palladium hydride <b>8</b> but leads to the diphosphine–hydroxy phosphine κ^P,P(OH),P pincer complex <b>9</b>

Ru(II)-Triphos Catalyzed Amination of Alcohols with Ammonia via Ionic Species

An active and selective system for the amination of primary alcohols to primary amines with ammonia based on ruthenium and triphos as the tridentate phosphine ligand was developed. On the basis of detailed mechanistic studies, we propose that the active catalyst is, unlike the previously reported systems on this reaction, a cationic ruthenium complex. The experimental findings are supported by detailed density functional theory (DFT) calculations on the catalytic cycle. Because of the cationic nature of the active catalyst, strong anion and solvent effects were observed in the catalytic amination reaction when using the ruthenium triphos complexes. Therefore, a higher activity could be achieved when the nonpolar solvent toluene is used in this amination instead of tetrahydrofuran. Our findings can help to develop and optimize the system systematically for an application to relevant target molecules

Correction to Oxidative Addition of Sn–C Bonds on Palladium(0): Identification of Palladium–Stannyl Species and a Facile Synthetic Route to Diphosphinostannylene–Palladium Complexes

Correction to Oxidative Addition of Sn–C Bonds on Palladium(0): Identification of Palladium–Stannyl Species and a Facile Synthetic Route to Diphosphinostannylene–Palladium Complexe