One-Pot and Step-by-Step N-Assisted C(Ph)-H Activation in 2-(4-Bromophenyl)imidazol[1,2-a]pyridine: Synthesis of a New C,N-Cyclometalated Compound [{Pt(C(boolean AND)N)(mu-Cl)}(2)] as Precursor of Luminescent Platinum(II) Compounds
Φόρτωση...
Ημερομηνία
Συγγραφείς
Fornies, J.
Sicilia, V.
Larraz, C.
Camerano, J. A.
Martin, A.
Casas, J. M.
Tsipis, A. C.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Organometallics
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
The activation of a C(ph)-H bond in the phenyl ring of 2-(4-bromophenyl)imidazol[1,2-a]pyridine (HC(boolean AND)N) by [{Pt(eta(3)-C(4)H(7))(mu-Cl)}(2)](eta(3)-C(4)H(7) = eta(3)-2-methylallyl) renders the new cyclometalated complex [Ppt(C(boolean AND)N)(mu-Cl)}(2)] (2) with high yield and selectivity. Complex 2 can be achieved directly in a one-pot reaction or step by step through the intermediate [Pt(eta(3)-C(4)H(7))Cl(HC(boolean AND)N-kappa N)] (1). Compound I could be isolated and fully characterized. The X-ray structure shows the coordination of HCA(boolean AND)N through only the N and the existence of a weak Pt center dot center dot center dot H-C hydrogen bridging bond (Pt center dot center dot center dot H1 = 2.78 angstrom, Pt center dot center dot center dot Cl = 3.365(3) angstrom, Pt-Hl-Cl = 120.9 degrees). Hence, the formation of this intermediate could be considered the first step in the cyclometalation process. The mononuclear complexes [PtCl(C(boolean AND)N)L] (L = tht (3), PPh(3) (4), CN-Xyl (5), CN-(t)Bu (6)) were obtained by cleavage of the bridging system in [{Pt(C(boolean AND)N)mu-Cl)}(2)] (2) by the neutral ligands, L. The resulting geometry (trans C, Cl) is that expected from the electronic preferences, taking into account the degree of transphobia (T) of pairs of trans ligands, T[C(C(boolean AND)N)/L(CI)] < T[C(C(boolean AND)N)/L(S, P, C)]. Complexes [PtCI(C(boolean AND)N)L] (L = CN-Xyl (5), CN-(t)Bu (6)) containing two strong-field ligands, a C(C)boolean AND N sigma-abonded and an isocyanide ligand, are luminescent. TD-DFT calculations were performed for the singlet ground state, S(0), as well as for the first triplet excited state of 6 in both the gas phase and solution. Calculations indicate that the lowest-lying absorption involves mainly (1)IL (C(boolean AND)N) mixed with a small contribution of (1)MLCT/(1)L'LCT (L = C(boolean AND)N; L' = Cl) transitions. Complex 5 exhibits "luminescent thermochromism" in the solid state; at 77 K it shows a green phosphorescence band assigned to (3)IL transitions located on the C(boolean AND)N group of monomer species, while at 298 K an orange-red emission is observed, being tentatively assigned to excited states of emissive aggregates ((3)MMLCT/(3)pi-pi*). However complex 6 shows phosphorescence only at 77 K both in Solution and in the solid state with the emissions arising from (3)IL and 3L'MLCT excited states of monomer species.
Περιγραφή
Λέξεις-κλειδιά
metal-carbon bonds, cyclometalated pt(ii) complexes, 5-membered ring compounds, ray crystal-structure, structural-characterization, iridium(iii) complexes, spectroscopic properties, photophysical properties, electronic spectroscopy, isocyanide ligands
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000275410300013
http://pubs.acs.org/doi/abs/10.1021/om901032v
http://pubs.acs.org/doi/abs/10.1021/om901032v
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας