ABSTRACT
The activation of 1,1-diphenyl-2-propyn-1-ol by the metallic fragment [(eta (5)-C 5Me 5)Ru(dippae)] (+) {dippae = 1,2-bis[(diisopropylphosphanyl)amino]ethane}, followed by dehydration, produces a cationic complex that, by deprotonation and rearrangement, leads to a neutral complex with a phosphinoallyl ligand containing a pyrrolidin-2-yl ring.
ABSTRACT
The syntheses of the chloro complexes [Ru(eta5-C5R5)Cl(L)] (R = H, Me; L = phosphinoamine ligand) (1a-d) have been carried out by reaction of [(eta5-C5H5)RuCl(PPh3)2] or {(eta5-C5Me5)RuCl}4 with the corresponding phosphinoamine (R,R)-1,2-bis((diisopropylphosphino)amino)cyclohexane), R,R-dippach, or 1,2-bis(((diisopropylphosphino)amino)ethane), dippae. The chloride abstraction reactions from these compounds lead to different products depending on the starting chlorocomplex and the reaction conditions. Under argon atmosphere, chloride abstraction from [(eta5-C5Me5)RuCl(R,R-dippach)] with NaBAr'4 yields the compound [(eta5-C5Me5)Ru(kappa3P,P'-(R,R)-dippach)][BAr'4] (2b) which exhibits a three-membered ring Ru-N-P by a new coordination form of this phosphinoamine. However, under the same conditions the reaction starting from [(eta5-C5Me5)RuCl(dippae)] yields the unsaturated 16 electron complex [(eta5-C5Me5)Ru(dippae)][BAr'4] (2d). The bonding modes of R,R-dippach and dippae ligands have been analyzed by DFT calculations. The possibility of tridentate P,N,P-coordination of the phosphinoamide ligand to a fragment [(eta5-C5Me5)Ru]+ is always present, but only the presence of a cyclohexane unit in the ligand framework converts this bonding mode in a more favorable option than the usual P,P-coordination. Dinitrogen [(eta5-C5R5)Ru(N2)(L)][BAr'4] (3a-d) and dioxygen complexes [(eta5-C5H5)Ru(O2)(R,R-dippach)][BPh4] (4a) and [(eta5-C5Me5)Ru(O2)(L)][BPh4] (4b,d) have been prepared by chloride abstraction under dinitrogen or dioxygen atmosphere, respectively. The presence of 16 electron [(eta5-C5H5)Ru(R,R-dippach)]+ species in fluorobenzene solutions of the corresponding dinitrogen or dioxygen complexes in conjunction with the presence of [BAr'4]- gave in some cases a small fraction of [Ru(eta5-C5H5)(eta6-C6H5F)][BAr'4] (5a), which has been isolated and characterized by X-ray diffraction.
ABSTRACT
The complexes [(C5R5)RuH(dippae)] [R = H (1a), Me (2a); dippae = 1,2-bis(diisopropylphosphinoamino)ethane] and [(C5R5)RuH((R,R)-dippach)] [R = H (1b), Me (2b); (R,R)-dippach = (R,R)-1,2-bis(diisopropylphosphinoamino)cyclohexane] have been prepared and characterized. The cationic ruthenium(IV) dihydride derivatives [(C5R5)RuH2(dippae)][BPh4] [R = H (3a), Me (4a)] and [(C5R5)RuH2((R,R)-dippach)][BPh4] [R = H (3b), Me (4b)] are also reported. No significant intramolecular interaction between the amino protons and the hydrogen atoms bound to the metal has been observed in any of these compounds. The X-ray crystal structure of 4a was determined. The proton-transfer processes over the monohydrides 2a and 2b with HBF4.OEt2 have been studied by NMR spectroscopy. Dicationic dihydride complexes [CpRuH2(LH)]2+ [LH = dippaeH+ (5a), (R,R)-dippachH+ (5b)] and [Cp*RuH2(LH)]2+ [LH = dippaeH+ (6a), (R,R)-dippachH+ (6b)] result respectively from the protonation of either the monohydrides 1a,b or 2a,b or the dihydrides 3a,b or 4a,b at one of the NH groups of the phosphinoamine ligands by an excess of HBF4. These dicationic derivatives exhibit fluxional behavior in solution. In the course of the protonation of 1a with HBF4.OEt2, a cationic dihydrogen complex and a dihydrogen-bonded derivative have been identified as intermediates by NMR spectroscopy. Another dihydrogen species, namely, [CpRu(H...HOOCPh)((R,R)-dippach)], was also identified in the course of the reaction of 1b with benzoic acid in toluene-d8. The reaction of 1a with 0.5 equiv of 1,1,1,3,3,3-hexafluoroisopropanol generates a hydride species having a very short (T1)min of 6.5 ms at 400 MHz, an experimental fact for which no satisfactory explanation has yet been found.
