Conformational Changes and Anion−Cation Interactions in Palladium-Cyclometalated BINAP and Chiraphos Cationic Complexes. A Structural Study via NMR and X-ray Methods

The cyclometalated Pd complexes [Pd{(A or B)C6H3CHN(p-CH3C6H4)}(BINAP)](X) (8−13; X = PF6-, BArF-, CF3SO3-, A, B = meta or para ring substituent), [Pd{(C6H4CH(CH3)N(CH3)2)}{(S)- or (R)-BINAP)}](CF3SO3) (14a,b), and [Pd{(C6H4CH(CH3)N(CH3)2)}{(S,S)- or (R,R)-Chiraphos)}](CF3SO3) (15a,b) have been prepared, and five of these have been studied by X-ray diffraction. NMR Overhauser measurements reveal that the chiral cyclometalated amine chelate senses the change in the chirality, for both the BINAP and the Chiraphos auxiliaries, and responds by a conformational adjustment of the ring. 1H,19F-HOESY data for both 14 and 15 suggest differences between the diastereomers 14a,b (and 15a,b). PGSE diffusion data for these salts are reported

Conformational Changes and Anion−Cation Interactions in Palladium-Cyclometalated BINAP and Chiraphos Cationic Complexes. A Structural Study via NMR and X-ray Methods

The cyclometalated Pd complexes [Pd{(A or B)C6H3CHN(p-CH3C6H4)}(BINAP)](X) (8−13; X = PF6-, BArF-, CF3SO3-, A, B = meta or para ring substituent), [Pd{(C6H4CH(CH3)N(CH3)2)}{(S)- or (R)-BINAP)}](CF3SO3) (14a,b), and [Pd{(C6H4CH(CH3)N(CH3)2)}{(S,S)- or (R,R)-Chiraphos)}](CF3SO3) (15a,b) have been prepared, and five of these have been studied by X-ray diffraction. NMR Overhauser measurements reveal that the chiral cyclometalated amine chelate senses the change in the chirality, for both the BINAP and the Chiraphos auxiliaries, and responds by a conformational adjustment of the ring. 1H,19F-HOESY data for both 14 and 15 suggest differences between the diastereomers 14a,b (and 15a,b). PGSE diffusion data for these salts are reported

Conformational Changes and Anion−Cation Interactions in Palladium-Cyclometalated BINAP and Chiraphos Cationic Complexes. A Structural Study via NMR and X-ray Methods

The cyclometalated Pd complexes [Pd{(A or B)C6H3CHN(p-CH3C6H4)}(BINAP)](X) (8−13; X = PF6-, BArF-, CF3SO3-, A, B = meta or para ring substituent), [Pd{(C6H4CH(CH3)N(CH3)2)}{(S)- or (R)-BINAP)}](CF3SO3) (14a,b), and [Pd{(C6H4CH(CH3)N(CH3)2)}{(S,S)- or (R,R)-Chiraphos)}](CF3SO3) (15a,b) have been prepared, and five of these have been studied by X-ray diffraction. NMR Overhauser measurements reveal that the chiral cyclometalated amine chelate senses the change in the chirality, for both the BINAP and the Chiraphos auxiliaries, and responds by a conformational adjustment of the ring. 1H,19F-HOESY data for both 14 and 15 suggest differences between the diastereomers 14a,b (and 15a,b). PGSE diffusion data for these salts are reported

Conformational Changes and Anion−Cation Interactions in Palladium-Cyclometalated BINAP and Chiraphos Cationic Complexes. A Structural Study via NMR and X-ray Methods

The cyclometalated Pd complexes [Pd{(A or B)C6H3CHN(p-CH3C6H4)}(BINAP)](X) (8−13; X = PF6-, BArF-, CF3SO3-, A, B = meta or para ring substituent), [Pd{(C6H4CH(CH3)N(CH3)2)}{(S)- or (R)-BINAP)}](CF3SO3) (14a,b), and [Pd{(C6H4CH(CH3)N(CH3)2)}{(S,S)- or (R,R)-Chiraphos)}](CF3SO3) (15a,b) have been prepared, and five of these have been studied by X-ray diffraction. NMR Overhauser measurements reveal that the chiral cyclometalated amine chelate senses the change in the chirality, for both the BINAP and the Chiraphos auxiliaries, and responds by a conformational adjustment of the ring. 1H,19F-HOESY data for both 14 and 15 suggest differences between the diastereomers 14a,b (and 15a,b). PGSE diffusion data for these salts are reported

Conformational Changes and Anion−Cation Interactions in Palladium-Cyclometalated BINAP and Chiraphos Cationic Complexes. A Structural Study via NMR and X-ray Methods

The cyclometalated Pd complexes [Pd{(A or B)C6H3CHN(p-CH3C6H4)}(BINAP)](X) (8−13; X = PF6-, BArF-, CF3SO3-, A, B = meta or para ring substituent), [Pd{(C6H4CH(CH3)N(CH3)2)}{(S)- or (R)-BINAP)}](CF3SO3) (14a,b), and [Pd{(C6H4CH(CH3)N(CH3)2)}{(S,S)- or (R,R)-Chiraphos)}](CF3SO3) (15a,b) have been prepared, and five of these have been studied by X-ray diffraction. NMR Overhauser measurements reveal that the chiral cyclometalated amine chelate senses the change in the chirality, for both the BINAP and the Chiraphos auxiliaries, and responds by a conformational adjustment of the ring. 1H,19F-HOESY data for both 14 and 15 suggest differences between the diastereomers 14a,b (and 15a,b). PGSE diffusion data for these salts are reported

Synthesis, X-ray, and NMR Studies on Palladium BINAP Complexes Containing Oxazolidinone and Acetylacetonate Anions

A series of monocationic palladium BINAP complexes, [Pd(rac-BINAP)(an oxazolidinone anion)][X] and [Pd(rac-BINAP)(an acetylacetonate anion)][X] (X = a, CF3SO3-; b, BF4-) (9−13), have been synthesized and characterized. A dicationic intermediate, pertinent to the Pd-catalyzed hydroamination reaction, arising from the reaction of the bis-aquo complex [Pd(H2O)2(rac-BINAP)]2(CF3SO3)2 and 1 equiv of an oxazolidinone, has been characterized via low-temperature NMR studies. The structures of the complexes [Pd(rac-BINAP)(CH3−C(O)−C(CH3)−C(O)−CH3)](BF4), 12b, and [Pd(μ-OH)(rac-BINAP)]2(CF3SO3)2 have been determined by X-ray diffraction. The solid-state structures of two separate forms of the BF4- salt 12b were obtained. One form of the salt can be thought of as a tight ion pair, whereas the second form contains a dichloromethane solvent molecule, packed in approximately a fifth coordination position together with a relatively remote BF4- anion. These structures represent a rare example where both ion pairing and strong solvation could be individually characterized. PGSE diffusion coefficients (D values) were measured for both the CF3SO3- and BF4- salts of 9−13 in CD2Cl2. In addition, D values were obtained for the CF3SO3- salts in THF and CDCl3 solutions. The amount of ion pairing decreases in the sequence CDCl3 > THF > CD2Cl2. The 1H,19F-HOESY spectra for the salts in CDCl3 suggest that the CF3SO3- is approaching the positive metal and phosphorus centers via a pathway that brings it closest to the P-phenyl groups but remote from the chelating anion

Diffusion and Overhauser NMR Studies on Dicationic Palladium Complexes of BINAP

PGSE diffusion, 1H,19F Overhauser, and related 2-D NMR studies on several salts of the dications [Pd(H2O)2(BINAP)]2+, [Pd(μ-OH)(BINAP)]22+, and [Pd2(μ-OH)(μ-NH(p-RC6H4))(BINAP)2], R = Cl, CH3, MeO, and, in one case, [Pd(μ-O2PF2)(BINAP)]2(PF6)2, are reported. These solution NMR results, together with DFT calculations, reflect on how the anion interacts with the cation, as well as the extent, and the solvent dependence of the ion pairing. The solid-state structure of [Pd2(μ-OH)(μ-{NH(p-Tol)})(BINAP)2](CF3SO3)2 has been determined

Synthesis and Reactivity of Ru(PPh₃)₃(CO)HF and the N-Heterocyclic Carbene Derivatives Ru(NHC)(PPh₃)₂(CO)HF

The reaction of Ru(PPh3)3(CO)H2 with excess Et3N·3HF at elevated temperature affords the hydride fluoride complex Ru(PPh3)3(CO)HF (1). This reacts with a series of N-heterocyclic carbenes (NHCs) at ambient temperature to form the mono-NHC products Ru(NHC)(PPh3)2(CO)HF (NHC = IMe4 (2), IEt2Me2 (3), ICy (4), IiPr2Me2 (5)). Complexes 2−4 convert from the trans- to cis-phosphine isomers in solution over weeks (relative rates 2 > 3 ≫ 4), while 5 undergoes both isomerization and disproportionation to yield cis-Ru(IiPr2Me2)(PPh3)2(CO)HF (6), 1, and Ru(IiPr2Me2)2(PPh3)(CO)HF (7) in a matter of hours. The molecular structures of compounds 1−4 have been determined by X-ray crystallography

Diffusion and Overhauser NMR Studies on Dicationic Palladium Complexes of BINAP

PGSE diffusion, 1H,19F Overhauser, and related 2-D NMR studies on several salts of the dications [Pd(H2O)2(BINAP)]2+, [Pd(μ-OH)(BINAP)]22+, and [Pd2(μ-OH)(μ-NH(p-RC6H4))(BINAP)2], R = Cl, CH3, MeO, and, in one case, [Pd(μ-O2PF2)(BINAP)]2(PF6)2, are reported. These solution NMR results, together with DFT calculations, reflect on how the anion interacts with the cation, as well as the extent, and the solvent dependence of the ion pairing. The solid-state structure of [Pd2(μ-OH)(μ-{NH(p-Tol)})(BINAP)2](CF3SO3)2 has been determined

Cationic Tris N-Heterocyclic Carbene Rhodium Carbonyl Complexes: Molecular Structures and Solution NMR Studies

The cationic N-heterocyclic carbene (NHC) rhodium complexes [Rh(NHC)3(CO)]+ (NHC = ICy (1), IiPr2Me2 (2)) have been isolated from the reactions of RhH(PPh3)3(CO) with the free NHCs. The hexafluorophosphate salts of both compounds, 1[PF6] and 2[PF6], have been characterized by X-ray diffraction. The observed temperature dependences of the 1H NMR spectra for 1[PF6] and 2[PF6] are a consequence of restricted rotation associated with the three Rh−CNHC bonds. Line shape analyses from the NMR studies on 1[PF6], 1[BAr4F], and 2[PF6] (BAr4F = B(3,5-C6H3(CF3)2)4) afford activation barriers for the two trans-positioned Rh−CNHC bonds of 35, 38, and 40 kJ mol-1, respectively. Pulsed-gradient spin−echo (PGSE) NMR measurements show that there is only a relatively small amount of ion pairing for these salts in dichloromethane solution. 1H−19F HOESY data help to place the anions relative to the cations. Preliminary mechanistic studies on the formation of 1 and 2 suggest a role for neutral dinuclear precursors, as revealed by the reaction of (PPh3)2Rh(μ-CO)2Rh(IiPr2Me2)2 with ICy, which affords the structurally characterized mixed NHC complex [Rh(IiPr2Me2)2(ICy)(CO)][PF6] (3[PF6])