Juan Forniés

New water soluble and luminescent platinum(II) compounds, vapochromic behavior of [K(H2O)][Pt(bzq)(CN)2], new examples of the influence of the counterion on the photophysical properties of d8 square-planar complexes.

This work describes the synthesis of compounds [Pt(C=N)(NCMe) 2]ClO 4 (C=N = 7,8-benzoquinolinato (bzq), 2-phenylpyridinato (ppy)) and their use as precursors for the preparation of the cyanido complexes [Pt(C=N)(CN) 2] (-), which were isolated as the potassium, [K(H 2O)][Pt(C=N)(CN) 2] [C=N = bzq ( 3a), ppy ( 4a)], and the tetrabutylammonium, NBu 4[Pt(C=N)(CN) 2] [C=N = bzq ( 5), ppy ( 6)], salts. The difference in the cation has an influence on the solubility, color, and emission properties of these compounds. Compounds 5 and 6 are yellow and soluble in organic solvents, while the potassium salts are also soluble in water and exhibit two forms: the water-containing [K(H 2O)][Pt(C=N)(CN) 2] [C=N = bzq ( 3a), ppy ( 4a)] complexes and the anhydrous ones K[Pt(C=N)(CN) 2] [C=N = bzq ( 3b), ppy ( 4b)], the former being strongly colored [red ( 3a) or purple ( 4a)] and the latter being yellow. Compounds 3a and 4a transform reversibly into the yellow, 3b and 4b, compounds upon desorption/ reabsorption of water molecules from the environment. The red solid, 3a, also exhibits vapochromic behavior when it is exposed to volatile organic compounds, the shortest response times being those observed for methanol and ethanol. UV-vis and emission spectra of all compounds were recorded both in solution and in the solid state. In methanol solution, the difference in the cation causes no differences in the absorption nor in the emission spectra, which is as expected for the monomer species. However, in the solid state, the differences are notable. For both the red ( 3a) and purple ( 4a) compounds, a prominent absorption, which has maxima at about 550 nm and is responsible for their intense colors, as well as a structureless emission at lambda > 700 nm that suffers a significant red-shift upon cooling, are due to (1,3)MMLCT (= metal-metal-to-ligand charge transfer) [dsigma*(Pt) --> pi*(C=N)] transitions characteristic of linear-chain platinum complexes with short Pt...Pt contacts. Time-dependent density-functional theory calculations on complex 5 and the X-ray diffraction study on compound [K(OCMe 2) 2][Pt(ppy)(CN) 2] ( 4c) are also included.

Highly Luminescent Half-Lantern Cyclometalated Platinum(II) Complex: Synthesis, Structure, Luminescence Studies, and Reactivity.

The half-lantern compound [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)]·Me(2)CO (1) was obtained by reaction of equimolar amounts of potassium 2-mercaptobenzothiazolate (KC(7)H(4)NS(2)) and [Pt(bzq)(NCMe)(2)]ClO(4). The Pt(II)···Pt(II) separation in the neutral complex [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)] is 2.910 (2) Å, this being among the shortest observed in half-lantern divalent platinum complexes. Within the complex, the benzo[h]quinoline (bzq) groups lie in close proximity with most C···C distances being between 3.3 and 3.7 Å, which is indicative of significant π-π interactions. The reaction of 1 with halogens X(2) (X(2) = Cl(2), Br(2), or I(2)) proceeds with a two-electron oxidation to give the corresponding dihalodiplatinum(III) complexes [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)X}(2)] (X = Cl 2, Br 3, I 4). Their X-ray structures confirm the retention of the half-lantern structure and the coordination mode of the bzq and the bridging ligand μ-C(7)H(4)NS(2)-κN,S. The Pt-Pt distances (Pt-Pt = 2.6420(3) Å 2, 2.6435(4) Å 3, 2.6690(3) Å 4) are shorter than that in 1 because of the Pt-Pt bond formation. Time dependent-density functional theory (TD-DFT) studies performed on 1 show a formal bond order of 0 between the metal atoms, with the 6p(z) contribution diminishing the antibonding character of the highest occupied molecular orbital (HOMO) and being responsible for an attractive intermetallic interaction. A shortening of the Pt-Pt distance from 2.959 Å in the ground state S(0) to 2.760 Å in the optimized first excited state (T(1)) is consistent with an increase in the Pt-Pt bond order to 0.5. In agreement with TD-DFT calculations, the intense, structureless, red emission of 1 in the solid state and in solution can be mainly attributed to triplet metal-metal-to-ligand charge transfer ((3)MMLCT) [dσ*(Pt-Pt) → π*(bzq)] excited states. The high quantum yields of this emission measured in toluene (44%) and solid state (62%) at room temperature indicate that 1 is a very efficient and stable (3)MMLCT emitter, even in solution. The high luminescence quantum yield of its red emission, added to its neutral character and the thermal stability of 1, make it a potential compound to be incorporated as phosphorescent dopant in multilayer organic light-emitting devices (OLEDs).

Mono- and bi-nuclear anionic pentafluorophenyl complexes of palladium(II) and platinum(II)

The arylation of K2[MCl4], [MCl2(tht)2], MCl2, or [NBu4]2[M2(µ-Br)2Br4](M = Pd or Pt; tht = tetrahydrothiophen) with LiR or MgBrR (R = C6F5) leads to novel mono- and bi-nuclear anionic organo-derivatives of the general formulae [MR3(tht)]–, [MR4]2–, and [M2(µ-Br)2R4]2–, which have been isolated as tetra-alkylammonium salts. Reaction of compounds of the [MR3(tht)]– type with neutral ligands leads to the substitution of tht by L, that of [PdR4]2– with PdCl2 gives rise to the formation of [Pd2(µ-Cl)2R4]2–, whilst [M2(µ-X)2R4]2– reacts with alkali-metal salts of Br–, I–, or SCN– to give (without cleavage of the bridging system) the corresponding complexes. Twenty anionic complexes of these three novel types have been isolated and characterized.

Synthesis of mono- and polynuclear perhalophenyl palladium-platinum acetylide complexes. Molecular structure of (NBu4)2[Pt2Ag2(C6F5)4(CCPh4] · 4CH2Cl2

Abstract The reaction between [Ag(CCR)]n (R = tBu, Ph) and the appropriate mononuclear palladium or platinum substrate affords mononuclear derivatives of the type [M(C6F5)(CCR)L2] (M = Pd, Pt; R = tBu, Ph; L = PPh3, dppe). Polynuclear (NBu4)2[Pt2Ag2(C6F5)4(CCPh)4] (X = F, Cl; R = Ph, tBu) complexes are obtained by reaction between (NBu4)2[Pt2(μ-X′)2(C6X5)4] (X′ = Cl, X = F; X′ = I, X = Cl) and [Ag(CCR)]n (Pt:Ag ratio 1:2). Similar heterometallic derivatives Q2[Pt2M2(C6F5)4 (CCR)4] (Q = PMePh3, NBu4; M = Ag, Cu; R = Ph, tBu) can be prepared by reaction of Q2[cis-Pt(C6F5)2(CCR)2] with AgCl or CuCl (Pt:M ratio 1:1). The structure of (NBu4)2[Pt2Ag2(C6F5)4 (CCPh)4]·4CH2Cl2 has been determined by X-ray diffraction.

Polynuclear platinum–silver, –copper, and –gold acetylide complexes. Molecular structure of [Pt2Ag4(CCBut)8]

Hexanuclear complexes [Pt2Ag4(CCR)8] [R = Ph (1) or But (2)] have been obtained by treating [PtCl2(tht)2] (tht = tetrahydrothiophene) with [Ag(CCR)]n(Pt/Ag 1 : 4). The complexes [Pt2M4(CCR)8] [M = Cu, R = Ph (3) or But (4); M = Au, R = But (5)] were obtained from [Pt2Ag4(CCR)8] with CuCl or [AuCl(tht)] respectively. Alternatively, the reactions between [NBu4]2[Pt(CCR)4] and AgClO4, CuCl–NaClO4, or [AuCl(tht)]–NaClO4 yield respectively complexes (1)–(5). The molecular structure of [Pt2Ag4(CCBut)8] has been determined by an X-ray diffraction study: monoclinic, space group C2 with a = 37.062(7), b = 12.0223(16), c = 20.459(3) A, β = 107.485(15)°, Z = 6, R 0.0416, R′ 0.0465 for 5 613 reflections with F > 6σ(F). The six metal atoms are arranged in a slightly irregular octahedron with the platinum atoms mutually trans and the silver atoms in the equatorial plane, with Pt ⋯ Ag and Ag ⋯ Ag distances longer than 3.0 A. Each platinum atom is in an almost square-planar environment formed by four CCBut ligands. Each acetylenic fragment also forms an asymmetric π interaction with one silver atom of the equatorial positions so that each silver atom is bonded to two acetylenic fragments, of two different Pt(CCBut), moieties. These moieties of each [Pt2Ag4(CCBut)8] unit are staggered.

Synthesis of novel platinum-silver and platinum-copper complexes with bridging alkynyl ligands

Abstract The study of the reactivity of [Pt 2 M 4 (CCR) 8 ] (MAg or cu; RPh or t Bu) towards different neutral and anionic ligands is reported. This study reveals that reactions of the phenylacetylide derivatives [Pt 2 M 4 (CCPh) 8 ] with anionic, X − (XCl or Br) or neutral donors (CN t Bu or py) in a molar ratio 1:4 (m/donor ratio 1:1) yield the trinuclear anionic (NBu 4 ) 2 [{Pt(CCPh) 4 (MX) 2 ] (MAg or Cu, X Cl or Br) or neutral [{Pt(CCPh0 4 =sAGL) 2 ] (LCN t Bu or py) complexes, respectively. The crystal structure of (NBu 4 ) 2 [{Pt(CCPh) 4 }(CuBr) 2 ]( 4 ) shows that the anion is formed by a dianionic Pt(CCPh) 4 fragment and two neutral CuBr units joined through bridging alkynyl ligands. All the alkynyl groups are σ bonded to Pt and η 2 -coordinated to a Cu atom which have an approximately trigonal-planar geometry. By contrast, similar reactions with [Pt 2 M 4 (CC t Bu) 8 ] (molar ratio M/donor 1:1) afford hexanuclear dianionic (NBu 4 ) 2 [Pt 2 M 4 (CC t Bu) 8 X 2 ] or neutral [Pt 2 Ag 4 (CC t Bu0 8 Py 2 ]. Only by treatment with a large exces of Br − (molar ratio M/Br − 1:2) are the trinuclear complexes (NBu 4 ) 2 [{Pt(CC t Bu 4 (MBr) 2 ] (MAg, Cu) obtained. Attempted preparations of analogous complexes with phosphines (L′PPh 3 or PEt 3 ) by reactions of [Pt 2 M 4 (CCR 8 ] with L′ leads to displacement of alkynyl ligands from platinum and formation of neutral mononuclear complexes [ trans -Pt(CCR) 2 L′ 2 ].

Mononuclear (Pd, Pt) and binuclear (Pd, Pd; Pd, Ag; Pt, Ag) complexes containing the bis(diphenylphosphino) amine ligand

Abstract By appropriate choice of precursors and solvent, complexes of the type M(C 6 X 5 ) 2 (dppa) 2 or M(C 6 X 5 ) 2 (dppa) (M = Pd, X = F, Cl; dppa = Ph 2 PNHPPh 2 ) can be prepared. Reaction of trans -M(C 6 F 5 ) 2 (dppa) 2 withAgClO 4 gives hereto-binuclear complexes of the type[(C 6 F 5 ) 2 M(μ-dppa) 2 Ag]ClO 4 . Addition of dppa to the perchlorato complexes Pd(OClO 3 )(C 6 F 5 )L 2 (L = PR 3 ) gives the cationic singly-bridged homo-binuclear species. [{Pd(C 6 F 5 )L 2 } 2 (μ-dppa)](ClO 4 ) 2 . The binuclear Pd 1 complex [{Pd(C 6 F 5 } 2 (μ-dppa) 2 ] has been obtained from the reaction between Pd(C 6 F 5 ) 2 (dppa) 2 and Pd 2 (dba) 3 ·CHCl 3 and its insertion reactions have been studied. The dppa ligand acts as monodentate, bidentate-chelate or bidentate-bridging ligand depending on the precursors, the solvent, and the reaction conditions.

Synthesis, structure and reactivity of homo- and hetero-polynuclear complexes of platinum bearing CCR groups as unique bridging ligands

Recent advances in the preparation of bi- or poly-nuclear platinum complexes bridged only by alkynyl ligands are described. Emphasis is placed not only on the co-ordination modes of alkynyl ligands but also on their migration and chemical activation.

Polynuclear homo- or heterometallic palladium(II) - platinum(II) pentafluorophenyl complexes containing bridging diphenylphosphido ligands. Synthesis and crystal structure of [(C6F5)2Pt(μ-PPh2)2Pt(phen)]

Abstract The binuclear anionic derivatives (NBu 4 ) 2 [(C 6 F 5 ) 2 M(μ-PPh 2 ) 2 M′(C 6 F 5 ) 2 ] (M = M′ = Pd, 1 ; M = M′ = Pt, 2 ; M = Pd, M′ = Pt, 3 ) have been obtained by treating either (NBu 4 ) 2 [(C 6 F 5 ) 2 M(μ-X) 2 M′(C 6 F 5 ) 2 ] (X = Cl, Br) with LiPPh 2 ( 1,2 ) or [ cis - M(C 6 F 5 ) 2 (PPh 2 ) 2 ] 2− with M′(C 6 F 5 ) 2 (THF) 2 ( 1,2,3 ). These binuclear derivatives react with HCl yielding the tetranuclear complexes (NBu 4 ) 2 [(C 6 F 5 ) 2 M(μ-PPh 2 ) 2 M′(μ-Cl) 2 M′(μ-PPh 2 ) 2 M(C 6 F 5 ) 2 ] ( 7 : M = M′ = Pt; 8 : M = M′ = Pd; 9 : M = Pt, M′ = Pd). However, 2 and 3 react with HCl in the presence of PPh 3 to yield the binuclear asymmetric complexes (NBu 4 )[(C 6 F 5 ) 2 M(μ-PPh 2 ) 2 M′(C 6 F 5 )(PPh 3 )] ( 10 : M = M′ = Pt; 11 : M = Pt, M′ = Pd). The tetranuclear complexes 7, 8 , and 9 react with bidentate ligands yielding the neutral asymmetric binuclear complexes [(C 6 F 5 ) 2 M(μ-PPh 2 ) 2 M′(LL)] ( 5 : M = M′ = Pt; LL = dppm; 12 : LL = phen; 13 : M = M′ = Pd, LL = bipy). The salts Li 2 [M(C 6 F 5 ) 2 (PPh 2 ) 2 ] (M = Pd, Pt) react with PtCl 2 (dppm), [Pt(μ-Cl)(C 6 F 5 )(tht)] 2 or PtCl 2 to yield [(C 6 F 5 ) 2 M(μ-PPh 2 ) 2 Pt-(dppm)] ( 4 : M = Pd; 5 : M = Pt), (NBu 4 )[(C 6 F 5 ) 2 Pt(μ-PPh 2 ) 2 Pt(C 6 F 5 )(tht)] ( 6 ) or (NBu 4 ) 2 [(C 6 F 5 ) 2 Pt(μ-PPh 2 ) 2 Pt(μ-Cl) 2 Pt(μ-PPh 2 ) 2 Pt(C 6 F 5 ) 2 ] ( 7 ), respectively. These complexes have been characterized by IR and 19 F and 31 P NMR spectroscopy, the latter indicating that in all cases no metal-metal bonds are present. The molecular structure of [(C 6 F 5 ) 2 Pt(μ-PPh 2 ) 2 Pt(phen)] has been established by an X-ray diffraction study. The Pt…Pt distance (3.5711(9) A) confirms that there is no PtPt bond.

Synthesis, structures and photophysics of novel luminescent platinum–copper complexes

Abstract The novel hexanuclear platinum–copper complex [Pt2Cu4(C6F5)4(CCtBu)4(acetone)2] (1) and the polynuclear derivative [PtCu2(C6F5)2(CCPh)2]x (2), which crystallises in acetone as [Pt2Cu4(C6F5)4(CCPh)4(acetone)4] (2)·(acetone)4, have been prepared using [cis-Pt(C6F5)2(THF)2] and the corresponding copper–acetylide [Cu(CCR)]x (molar ratio 1:2) as starting materials. Treatment of 1 and 2 with 2,2′-bipyridine (molar ratio Cu–bipy 1:1), afforded the new trinuclear derivatives [{cis-Pt(C6F5)2(μ-CCR)2}{Cu(bipy)}2] (R=tBu 3, Ph 4), in which the dianionic 3-platina-1,4-diyne acts as a didentate bridging ligand to two different cationic Cu(bipy) units through η2-side-on coordination of the alkynyl fragments. While similar treatment of 1 with dppe (Cu–dppe 1:1) yielded [{cis-Pt(C6F5)2(μ-CCtBu)2}{Cu(dppe)}2] (5), the analogous reaction of 2 with dppe afforded a mixture of complexes containing [Pt(C6F5)(CCPh)(dppe)] as the main platinum compound. The crystal structures of 1, 2·(acetone)4, 3 and 4 and the luminescent behaviour of all complexes have been determined. A comparison of the photoluminescent spectra of 1 and 2 with those of the related platinum–silver species [PtAg2(C6F5)2(CCR)2]x and the monomeric [cis-Pt(C6F5)2(CCR)2]2− suggests the presence of emitting states bearing a large cluster [PtM2]x-to-ligand (alkynide) charge transfer (CLCT).