142 research outputs found
Elucidation of the Structure and Fluxionality of a Dinuclear Organometallic Complex Reluctant to Crystallize: An Experimental and Theoretical Integrated Approach
No full textThe organometallic dication 12+ has been constructed by
combining the angular py-functionalized ligand N,N’-bis-(3-
aminopyridine)-1,4,5,8-naphthalenetetracarboxydiimide (L) with
[(p-cymene)RuCl] moieties. In 12+ two ligands L bridge two
organometallic nodes. Repeated crystallization attempts of 12+
failed and then a combined DFT/VT-1HNMR/UV-Vis spectroscopy
study has been performed to define the most plausible
structure of the dication. These considers the two naphthalenediimide
platforms unstacked, thus giving rise to a very open
conformation where the two chloride and the two p-cymene
ligands lye on the same side of the cationic cleft. The high
fluxionality of 12+ evidenced by 1HNMR spectroscopy has been
elucidated by a combined PES (Potential Energy Surface)/MD
(Molecular Dynamic)/DFT-GIAO (Gauge Including Atomic Orbitals)
study, thus furnishing a detailed description of the
dynamic character of 12+
Supramolecular Architectures of Pt(II) Complexes Controlled byHydrogen Bonds and by Guest Molecules
No full textStruttura molecolare e organizzazione cristallina di complessi di argento a struttura wheel-and-axle
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Diastereomeric half-sandwich Ru(II) cationic complexes containing amino amide ligands. Synthesis, solution properties, crystal structure and catalytic activity in transfer hydrogenation of acetophenone
No full textThe cationic complexes [(g6-arene)Ru(N,O-amino amide)X]Y (arene = p-cymene or indane; N,O-amino
amide = (L)-proline amide or (L)-phenylalanine amide; X = Cl or I; Y = Cl, I or PF6) have been synthesised
and fully characterized by spectroscopic and analytical methods. In several cases (1a, 3a, 4a, 4b, 5) the
metal configuration has been definitively established by X-ray analysis on single crystal. The lability of
the metal center in solution has been studied by 1H NMR and CD techniques. The highest configurational
stability has been found in the complexes of the type [(g6-indane)Ru(N,O-proline amide)Cl]Y (4a,b). The
complexes 1b, 2a–b, 3b, 4b and 5 are good precatalysts for the transfer hydrogenation of acetophenone in
basic i-PrOH, with ee up to 76% at 30 _C. An ESI(+)-MS study of pre-catalytic solutions has provided useful
information on the catalytic mechanism
Photoinduced alkaline pH-jump on the nanosecond time scale
No full textThe triphenylmethane leucohydroxide salt 4-(dimethylamino)-4'-(trimethylammonium) triphenylmethanol iodide has been used as a photoactivatable caged hydroxide to rapidly increase the pH of a neutral aqueous solution on the nanosecond time scale. Photoexcitation of the compound with a nanosecond ultraviolet laser pulse results in the formation of a colored carbocation with a rate greater than 108 s-1; recombination occurs with a multiexponential kinetics. The dissociation is completely reversible on time scales of 102 s and offers a large time window after the pH jump, in which the proton transfer reactions can be studied. The effectiveness of the photodissociation process to increase the pH of the solution has been demonstrated by means of the pH indicator bromoxylenol blue
Synthesis, structure and catalytic behaviour of half-sandwich Ru(II) complexes containing L-prolineamide and L-phenylalanineamide
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