131458-03-2Relevant articles and documents
Base-induced dehydrogenation of ruthenium hydrazine complexes
Field, Leslie D.,Li, Hsiu L.,Dalgarno, Scott J.,McIntosh, Ruaraidh D.
, p. 1570 - 1583 (2013/04/10)
Treatment of [RuCl(PP3iPr)]+Cl- (PP3iPr = P(CH2CH2P iPr2)3) with hydrazine, phenylhydrazine, and methylhydrazine afforded side-on bound hydrazine complexes [RuCl(η 2-H2N-NH2)(η3-PP 3iPr)]+, [RuCl(η2-H 2N-NHPh)(η3-PP3iPr)] +, and [RuCl(η2-H2N-NHMe) (η3-PP3iPr)]+. The analogous reactions of [RuCl2(PP3Ph)] (PP 3Ph = P(CH2CH2PPh2) 3) with hydrazine, phenylhydrazine, and methylhydrazine afforded end-on bound hydrazine complexes [RuCl(η1-H2N-NH 2)(PP3Ph)]+, [RuCl(η 1-H2N-NHPh)(PP3Ph)]+, and [RuCl(η1-H2N-NHMe)(PP3Ph)] +. Treatment of parent hydrazine complex [RuCl(N2H 4)(PP3iPr)]+ with strong base afforded the dinitrogen and dihydride complexes [Ru(N2)(PP 3iPr)] and [RuH2(PP3 iPr)]. Treatment of phenylhydrazine complex [RuCl(NH 2NHPh)(PP3iPr)]+ with strong base afforded the hydrido ruthenaindazole complex [RuH(η2-NHi? - ?NC6H4)(η3-PP3iPr)] while similar treatment of methylhydrazine complex [RuCl(NH2NHMe) (PP3iPr)]+ afforded the hydrido methylenehydrazide complex [RuH(NHNi? - ?CH2)(PP 3iPr)]. Treatment of the hydrazine complexes [RuCl(NH 2NHR)(PP3Ph)]+ (R = H, Ph, Me) with strong base afforded the dinitrogen complex [Ru(N2)(PP 3Ph)].
Photochemistry of M(PP3)H2 (M = Ru, Os; PP3 = P(CH2CH2PPh2)3): Preparative, NMR, and time-resolved studies
Osman, Robert,Pattison, David I.,Perutz, Robin N.,Bianchini, Claudio,Casares, Juan A.,Peruzzini, Maurizio
, p. 8459 - 8473 (2007/10/03)
Photochemical reaction of Ru(PP3)H2 (PP3 = P(CH2CH2PPh2)3) in THF under a rigorously inert atmosphere yields the cyclometalated complex Ru[(Ph2PCH2CH2)2P(CH2CH2PPhC6H4)]H. The latter is converted back to Ru(PP3)H2 under H2 and reacts even with traces of N2 to yield Ru(PP3)(N2). The dinitrogen complex may be synthesized directly by a number of methods. NMR spectroscopy shows that photolysis of Ru(PP3)H2 under C2H4 and CO yields Ru(PP3)(C2H4) and Ru(PP3)(CO), respectively, Photolysis of Ru(PP3)H2 with HSiEt3 in THF yields Ru(PP3)(SiEt3)H, while photolysis in mixtures of THF and benzene at low temperature yields Ru(PP3)(Ph)H. The latter is also generated by reduction of Ru(PP3)Cl2 in the presence of benzene. Os(PP3)(Ph)H is formed either by photolysis of Os(PP3)H2 or by reduction of Os(PP3)Cl2 in the presence of benzene. Irradiation of Os(PP3)H2 in THF or THF/hexane mixtures initially yields the THF C-H activation product, Os(PP3)(2-C4H7O)H. This complex is also generated by reduction of Os(PP3)Cl2 with sodium naphthalenide under N2 in the presence of THF. Os(PP3)-(2-C4H7O)H is converted to the cyclometalated complex, Os[(Ph2PCH2CH2)2P(CH2CH2PPhC6H4)]H, on irradiation in THF and to Os(PP3)(Ph)H on irradiation in benzene. Reaction of Os(PP3)H2 with CH3OTf (Tf = triflate) yields Os(PP3)(OTf)H, which is converted to the labile Os(PP3)(CH3)H on reaction with methyllithium. Laser flash photolysis of Ru(PP3)H2 in cyclohexane (laser wavelength 308 nm) yields transient Ru(PP3) with an absorption maximum at 395 nm. The transient reacts with H2, C6H6, HSiEt3, CO, N2, C2H4, and THF with little discrimination; the second-order rate constants for these reactions lie in the range 5 x 105-2 x 106 dm3 mol-1 s-1 at 295 K. Kinetic isotope effects have been determined for the reaction with benzene and THF, as 1.5 (0.2) and 1.1 (0.2), respectively. Activation parameters for reaction of Ru(PP3) are as follows: with HSiEt3 ΔH≠ = 35 (2) kJ mol-1, ΔS≠ = -18 (6) J K-1 mol-1; with C6H6 ΔH≠ = 39 (4) kJ mol-1, ΔS≠ ~0 J K-1 mol-1. The reaction with THF yields a short-lived adduct, probably bound through oxygen, which is rapidly converted to the cyclometalated product. Laser flash photolysis of Os(PP3)H2 generates transient Os(PP3) (λ(max) = 390 nm). The transient kinetics of Os(PP3) are substantially different from its ruthenium analogue. It reacts with alkanes and shows different behavior toward THF but is unaffected by addition of H2. Rate constants in the range 6 x 104-6 x 105 dm3 mol-1 s-1 (295 K) are presented for reaction with C6H6, THF, HSiEt3, CO, C2H4, N2, and several alkanes. Kinetic isotope effects have been determined for the reactions with methylcyclohexane and benzene as 5.6 (1.5) and 0.6 (0.1), respectively. The rate constants for reaction with alkanes rise in the order, methylcyclohexane 3) with THF to form Os(PP3)-(THF), C-H insertion occurs with a first-order rate constant of 4.2 (8) x 103 s-1 with k(H)/k(D) = 2.6 (0.4). The activation parameters for reaction of Os(PP3) with substrates are as follows: with pentane ΔH≠ = 27 (1) kJ mol-1, ΔS≠ = -59 (4) J K-1 mol-1; with HSiEt3 ΔH≠ = 31 (5) kJ mol-1, ΔS≠ = -27 (12) J K-1 mol-1; with C6H6 ΔH≠ = 38 (3) kJ mol-1, ΔS≠ = -7 (9) J K-1 mol-1.
Classical and nonclassical polyhydride ruthenium(II) complexes stabilized by the tetraphosphine P(CH2CH2PPh2)3
Bianchini, Claudio,Perez, Pedro J.,Peruzzini, Maurizio,Zanobini, Fabrizio,Vacca, Alberto
, p. 279 - 287 (2008/10/08)
The dichloride [(PP3)RuCl2] (1) is selectively transformed into [(PP3)Ru(H)(η1-BH4)] (2), [(PP3)Ru(H)Cl] (3), and [(PP3)-Ru(H)2] (4) by reaction with NaBH4, LiHBEt3, and LiAlH4, respectively [PP3 = P(CH2CH2PPh2)3]. Complex 2 is fluxional on the NMR time scale in ambient-temperature solutions due to equilibration of the BH4- hydrogens through cleavage of the Ru-Hb-B bridge and interconversion of Ht by rotation. The hydride-tetrahydroborate complex exhibits amphoteric nature: it reacts with protic acids, yielding the cis-hydride-dihydrogen complex [(PP3)Ru(H)(η2-H2)]Y (Y = PF6, 6a; BPh4, 6b), and with bases such as PEt3 or KOtBu, converting to the dihydride 4. The latter compound can be obtained also by thermal decomposition of 2 in refluxing toluene or benzene. Complexes 6a,b can be prepared by reaction of the dihydride 4 with protic acids. The nonclassical structure of 6a,b is established by variable-temperature 1H and 31P NMR data, T1 measurements and J(HD) values. In the solid state and in solution at low temperature [(PP3)Ru(H)(η2-H2)]+ is octahedral, and the hydride and dihydrogen ligands occupy mutually cis positions. At ambient temperature in solution the complex is trigonal-bipyramidal and the equilibration of the hydrogens might proceed through an H3 unit occupying an axial position trans to the bridgehead phosphorus atom of PP3. Octahedral monohydride complexes of the type [(PP3)Ru(H)(L)]BPh4 are obtained from 6b by substitution of dihydrogen with the appropriate ligand (L = N2, CO, PEt3, CH3CN, SO2). In all cases, the hydride ligand is located trans to a terminal phosphorus of the ligand. The role played by the tripodal tetradentate phosphine PP3 in the stabilization, in the fluxionality, and in the structure of all of the present Ru complexes is amply discussed.
