123122-81-6Relevant articles and documents
Ab Initio and Experimental Studies on the Structure and Relative Stability of the cis-Hydride-η2-Dihydrogen Complexes [{P(CH2CH2PPh2)3}M (H)(η2-H2)]+ (M = Fe, Ru)
Bianchini, Claudio,Masi, Dante,Peruzzini, Maurizio,Casarin, Maurizio,Maccato, Chiara,Rizzi, Gian Andrea
, p. 1061 - 1069 (2008/10/09)
Ab initio calculations (DMOL method) including the estimate of the total energy and the full optimization of the geometrical parameters have been used to study the electronic structures and the coordination geometries of the model systems [{P(CH2CH2PH2)3}M (H) (L)]+ (M = Fe, L = H2, C2H4, CO, N2; M = Ru, L = H2). Single crystal X-ray analyses have been carried out on the complexes [(PP3)Fe (H)(η2-H2)]BPh4·0.5THF (1·0.5THF), [(PP3)Fe (H)(CO)]BPh4·THF(3·THF), and [(PP3)Ru (H)(η2-H2)]BPh 4·0.5THF(5·0.5THF) [PP3 = P(CH2CH2PPh2)3]. Crystal data: for 1·0.5THF, triclinic P1 (No. 2), a = 17.626(3) A?, b = 14.605(3) A?, c = 12.824(4) A?, α = 90.09(2)°, β = 103.87(2)°, γ = 107.46(2)°, Z = 2, R = 0.082; for 3·THF, triclinic P1 (No. 2), a = 12.717(2) A?, b = 14.553(1) A?, c = 17.816(2) A?, α = 72.90(1)°, β = 76.82(2)°, γ = 89.71(1)°, Z = 2, R = 0.067; for 5·0.5THF, monoclinic P2/1a (No. 14), a = 19.490(5) A?, b = 19.438(2) A?, c = 16.873(5) A?, β= 110.96(2)°, Z = 4, R = 0.074. On the basis of theoretical calculations, X-ray analyses, and multinuclear NMR studies, all of the complexes of the formula [(PP3)M (H) (L)]BPh4 [M = Fe, L = H2 (1), C2H4 (2), CO (3), N2 (4); M = Ru, L = H2 (5), C2H4 (6)] are assigned a distorted octahedral structure where the hydride (trans to a terminal phosphorus donor) and the L ligand occupy mutually cis positions. The theoretical calculations indicate that the H2 ligand in the η2-dihydrogen-hydride derivatives 1 and 5 is placed in the P-M-H plane (parallel orientation) and that there is an attractive interaction between the H and H2 ligands. XPS measurements, performed on the iron complexes, show that the Fe → L back-bonding interaction plays a leading role in 3. It is concluded that the stronger metal-H2 bond in the dihydrogen-hydride complex 1, as compared to the Ru analog 5, is due to the greater d(metal) → σ*(H-H) back-donation as well as a more efficient interaction between the terminal hydride and an H of the dihydrogen ligand. This cis effect is suggested to contribute to the relative stability of the iron complexes, which increases in the order C2H4 2 2 CO.
Electrochemistry as a diagnostic tool to discriminate between classical M-(H)2 and nonclassical M-(H2) structures within a family of dihydride and dihydrogen metal complexes
Bianchini, Claudio,Laschi, Franco,Peruzzini, Maurizio,Ottaviani, Francesca M.,Vacca, Alberto,Zanello, Piero
, p. 3394 - 3402 (2008/10/08)
The redox properties of a family of dihydride and dihydrogen complexes of iron, cobalt, rhodium, and iridium have been studied in detail and compared with those of the corresponding monohydrido derivatives. All of the complexes contain as stabilizing coligands either P(CH2CH2PPh2)3 (PP3) or N(CH2CH2PPh2)3 (NP3). The novel dihydride [(PP3)Fe(H)2] and its isotopomers [(PP3)Fe(H)(D)] and [(PP3)Fe(D)2] have been fully characterized by IR and 1H and 31P NMR techniques. The complexes [(PP3)Co(H2)]PF6 and [(PP3)Rh(H2)]BF4, which exhibit the nonclassical dihydrogen structure, undergo in tetrahydrofuran irreversible one-electron oxidation. As a result, the deprotonation of the H2 ligand occurs and the starting η2-H2 compounds are converted to the corresponding monohydrides [(PP3)MH]+ (M = Co, Rh). In contrast, the classical dihydrides [(L)Ir(H)2]BPh4 (L = PP3, NP3) and [(NP3)Rh(H)2]BPh4 show no redox activity within the potential window of tetrahydrofuran. The dihydride [(PP3)Fe(H)2)] can be oxidized to give the unstable species [(PP3)Fe(H)2]+ and [(PP3)Fe(H)2]2+, but no deprotonation reaction occurs. The cis-(hydride)(dihydrogen) complex [(PP3)Fe(H)(H2)]BPh4 undergoes one-electron reduction in tetrahydrofuran to give the neutral dihydride. Rare examples of paramagnetic monohydrides of cobalt(II), rhodium(II), iron(I), and iron(II) have been synthesized chemically or electrochemically and characterized by X-band ESR spectroscopy.
An Exceptionally stable cis-(hydride)(η2-dihydrogen) complex of iron
Bianchini, Claudio,Perzzini, Maurizio,Zanobini, Fabrizio
, p. C19 - C22 (2007/10/02)
The cis-(H)(H2) complex BPh4 (PP3=P(CH2CH2PPh2)3) has been made by reaction of the chloride BPh4 in THF with NaBH4 under 1 atm of H2.In the solid state and in solution at low temperature the complex is octahedral, and the hydrid
