109750-49-4Relevant academic research and scientific papers
Preparation and spectroscopic properties of the η2-dihydrogen complexes [MH(η2-H2)(PR2CH2CH 2PR2)2]+ (M = Fe, Ru; Ru; R = Ph, Et) and trends in properties down the iron group triad
Bautista, Maria T.,Cappellani, E. Paul,Drouin, Samantha D.,Morris, Robert H.,Schweitzer, Caroline T.,Sella, Andrea,Zubkowski, Jeffery
, p. 4876 - 4887 (2007/10/02)
Complexes trans-[M(H)(η22)L2]BF4 (L = PPh2CH2CH2PPh2 = dppe (1Fe, 1Ru), PEt2CH2CH2PEt2 = depe (2Ru)) are prepared by reaction of cis-M(H)2L2 with 1 equiv of HBF4·Et2O. Deprotonation of 1Ru by BuLi at 200 K, gives thermally unstable trans-Ru(H)2(dppe)2, which isomerizes to cis-Ru(H)2(dppe)2. Tetraphenylborate salts of the complexes 1Fe, 2Fc, and 2Ru are prepared by reaction of trans-M(Cl)(H)L2 with NaBPh4 under 1 atm of H2. 2Fe, 1Ru, and 2Ru can also be made directly from the complexes cis-MC2L2 by reaction with 1 atm of H2, excess NaBPh4, and 1 equiv of NaOEt (or NaOtBu) in THF. Some properties of the complexes [Os(H)(H2)(L)2]+ (L = dppe (1Os), depe (2Os)) are included to reveal trends down the triad of metals; ReH3(dppe)2 also provides useful comparisons. The terminal hydride stretching mode, ν(M-H), increases in frequency as Fe 31P chemical shifts increase in the order Fe 1H NMR spectra of isotopomers trans-[M(H)(η2-HD)L2]+ and trans-[M(D)(η2-HD)L2]+ give couplings 1J(H,D) that decrease as Ru > Fe > Os. The chemical shifts of the HD for these two isotopomers are quite different because of the higher trans influence of D than H. The chemical shift difference, δ(dihydrogen) - δ(terminal hydride), for complexes 1 and 2 also decreases as Ru > Fe > Os. The T1 values of the dihydrogen nuclei, T1(H2), and the hydride ligand, T1(H), were determined over the temperature range of 190-300 K for the complexes 2Fe and 2Ru in acetone-d6. Analysis of these and other data suggests H-H distances for the rapidly spinning H2 ligand of the Fe and Ru complexes are comparable at 0.87 ± 0.02 A?. An overall ordering of increasing distances is Ru ≈ Fe 2/D2 rates of exchange increases as Os 2 binding and hence the strength of the H2-metal bond likely increases as Ru 2]+ unit is a poorer π-back-bonder than the corresponding complexes of either Fe or Os and forms weaker σ-bonds than Os. Electrochemical and infrared data both indicate that the ease of oxidation of the binding sites for N2 and Cl- decreases as ReH(dppe)2 Gt; [FeH(depe)2]+ > [FeH(dppe)2]+ > [MH(depe)2]+ > [MH(dppe)2]+ (M = Ru, Os). H atom exchange between H2 and hydride ligands is monitored by variable-temperature 1H NMR, and spectra are simulated to give ΔG? values that decrease as Ru > Fe > Os and dppe > depe. This exchange likely proceeds via the homolytic cleavage of the H-H bond.
Single-Crystal X-ray and Neutron Diffraction Studies of an η2-Dihydrogen Transition-Metal Complex: trans-2-H2)(H)(PPh2CH2CH2PPh2)2>BPh4
Ricci, John S.,Koetzle, Thomas F.,Bautista, Maria T.,Hofstede, Theresa M.,Morris, Robert H.,Sawyer, Jeffery F.
, p. 8823 - 8827 (2007/10/02)
The H-H distance in the η2-H2 ligand in 2-H2)H(dppe)2>BPh4, 1-BPh4, dppe=PPh2CH2CH2PPh2, is 0.816(16) Angstroem as determined by neutron diffraction on a crystal of volume 2.62 mm3 at 20 K: 1-BPh4 is monoclinic, space
