Showing papers by "M. Teresa Moreno published in 2012"

Facile metalation of Hbzq by [cis-Pt(C6F5)2(thf)2]: a route to a pentafluorophenyl benzoquinolate solvate complex that easily coordinates terminal alkynes. Spectroscopic and optical properties.

Abstract: A new neutral cyclometalated platinum(II) solvate complex [cis-Pt(bzq)(C6F5)(acetone)] (1) has been prepared by easy C–H activation of 7,8-benzo[h]quinoline on the coordination sphere of [cis-Pt(C6F5)2(thf)2] (thf = tetrahydrofuran). The study of the reaction pathway has led us to the preparation of the bis(Hbzq) product [cis-Pt(C6F5)2(Hbzq)2] (2) and the benzoquinoline–benzoquinolate derivative [Pt(bzq)(C6F5)(Hbzq)] (3). This latter complex has been characterized by X-ray diffraction, showing the occurrence of π···π intermolecular stacking interactions associated to the deprotonated bzq units. The acetone molecule in [cis-Pt(bzq)(C6F5)(acetone)] can be easily displaced by alkynes, allowing the synthesis of the first reported η2-alkyne-cycloplatinate complexes [Pt(bzq)(C6F5)(η2-RC≡CR′)] (R = H, R′ = Ph 4, tBu 5, Fc 6; R = R′ = Ph 7), which have been fully characterized spectroscopically and by DFT studies. These alkyne complexes are only moderately stable in solution, and all attempts to obtain crystals s...

Luminescent benzoquinolate-isocyanide platinum(II) complexes: effect of Pt⋅⋅⋅Pt and π⋅⋅⋅π interactions on their photophysical properties.

Abstract: This work was supported by the Spanish MICINN [Projects CTQ2008-06669-C02-01,02 and the Gobierno de Aragon (Grupo Consolidado: Quimica Inorganica y de los Compuestos Organometalicos). P.B. and A.D. acknowledge the support of a FPI grant from the MICINN.

Benzoquinolateplatinum(II) complexes as building blocks in the synthesis of Pt–Ag extended structures

Abstract: The reaction between (NBu(4))[Pt(bzq)(C(6)F(5))(2)] (1, bzq = 7,8-benzoquinolate) and AgClO(4) in a 1 : 1 molar ratio, in acetone, gives the polymer [{Pt(bzq)(C(6)F(5))(2)}Ag](n) (2). The reaction of 2 with equimolecular amounts of PPh(3) and SC(4)H(8) (tht) produces the bimetallic complexes [{Pt(bzq)(C(6)F(5))(2)}AgL] (L = PPh(3) (3), tht (4)). For L = py, decomposition takes place and [Pt(bzq)(C(6)F(5))py] (5) is obtained. All these complexes have been characterized by X-ray diffraction. The most interesting features of complexes 2-4 is the presence of Pt-Ag bonds, with Pt-Ag distances of ca. 2.75 A. Besides, the silver centres establish short η(1) bonding interactions with the C(ipso) of the bzq ligands, with distances Ag-C of ca. 2.45 A. Complex 2 is a one-dimensional infinite chain in which the fragments "Pt(bzq)(C(6)F(5))(2)(-)" and Ag(+) alternate. On the other hand, complexes 1 and 3-5 show intermolecular pairing through π···π interactions between the aromatic rings of the bzq ligand, having interplanar separations of ca. 3.5 A. Complex 2 dissolves in donor solvents (acetone, THF) as discrete bimetallic solvated fragments [{Pt(bzq)(C(6)F(5))(2)}AgS(n)] (S = solvent), similar to complexes 3 and 4. The persistence of the Pt-Ag bond in 2-4, supported by multinuclear NMR spectroscopy, causes a significant blue-shift in the lowest-lying absorption in relation to 1. This fact is attributed (TD-DFT) to a remarkable modification of the orbitals contributing to the HOMO, which changes the character of the transition from (1)LC/(1)MLCT in 1 to admixture (1)L'LCT/(1)MLCT in the bimetallic complexes. The low energy feature (490-530 nm) of 2 in solid state is attributed to CT from the Pt fragments to the Ag centers. Complexes 2-4 are only emissive in rigid media (solid and glasses). In the solid state, the metallic chain 2 exhibits a bright orange emission (560 nm, 298 K; 590 nm, 77 K), assigned to an excited state involving charge transfer from the platinum fragment with a remarkable contribution of C(6)F(5) (Ar(f)) rings to the Pt-Ag bond ((3)LMM'CT/(3)L'M'CT). However, 3 and 4 exhibit in solid state at 298 K a vibronic band, which is clearly resolved in two close non-equilibrated bands at 77 K in 3, tentatively ascribed to a mixture of (3)MLCT/(3)L'LCT transitions modified by the formation of the Pt-Ag bond. In glassy solution (77 K) 2-4 display a vibronic emission ascribed primarily to (3)LC character.

Platinum(0) Complexes with Alkynylphosphane Ligands

Abstract: The reactivity of the Pt0 derivative [Pt2(dba)3] (dba = trans,trans-dibenzylideneacetone) towards PPh2C≡CR [R = Ph, tolyl (Tol), C5H4N-2] and PPh2C≡CPPh2 (dppa) has been explored. Treatment of [Pt2(dba)3] with PPh2C≡CR (8 equiv.) in THF gave the tetrahedral complexes [Pt(PPh2C≡CR)4] [R = Ph (1), Tol (3), C5H4N-2 (5)], whereas reactions with a molar ratio of 1:4 afforded the binuclear derivatives [{Pt(PPh2C≡CR)(μ-κP:η2-PPh2C≡CR)}2] [R = Ph (2), Tol (4) X-ray, C5H4N-2 (6)], which were shown to be generated through the mononuclear complexes 1, 3 and 5 as intermediate species. An analogous reaction using 4 equiv. of PPh2C≡CPPh2 afforded [Pt2(PPh2C≡CPPh2)2(μ-κ2PP′-PPh2C≡CPPh2)3] (7), in which two “Pt(PPh2C≡CPPh2)” fragments are joined through three bridging dppa ligands (μ-κ2PP′-PPh2C≡CPPh2). Attempts to crystallize 7 at –30 °C afforded crystals of [Pt2{PPh2C≡CP(O)Ph2}2(μ-κ2PP′-PPh2C≡CPPh2)3] (8) by oxidation of the free end of the terminal dppa ligands. The compound was characterized by X-ray diffraction.