Irene Ara

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).

Neutral and anionic binuclear perhalogenophenyl platinum–silver complexes with Pt→Ag bonds unsupported by covalent bridges. Molecular structures of [(tht)(C6Cl5)(C6F5)2-PtAg(PPh3)], [NBu4][(C6F5)4PtAg(tht)] and [NBu4][cis-(C6Cl5)2(C6F5)2PtAg(tht)](tht = tetrahydrothiophene)

Heterobinuclear complexes of general formula [L(C6Cl5)3-x(C6F5)xPtAg(PPh3)][x= 2–0; L = tht (tetrahydrothiophene), PPh3 or pyridine (py)]14–21 have been prepared by treating the anionic platinum derivatives [NBu4][PtL(C6F5)x(C6Cl5)3-x] with [Ag(OCIO3)(PPh3)](molar ratio 1 : 1) in dichloromethane. The anionic [NBu4][(C6F5)4PtAgL](L = OEt2, PPh3 or tht)22–24 and [NBu4][cis-(C6Cl5)2(C6F5)2PtAg(tht)]25 have been obtained from the corresponding [NBu4]2[Pt(C6X5)2(C6X′5)2] and [Ag(OCIO3)L](molar ratio 1 : 1) in CH2Cl2–diethyl ether. The reaction between [NBu4][Pd(C6F5)3(tht)] and [Ag(OCIO3)(PPh3)] renders Ag(C6F5) and cis-[Pd(C6F5)2(PPh3)(tht)]. The salts [NBu4]2[Pt(C6Cl5)4] and [NBu4]2[Pd(C6F5)4] react with [Ag(OCIO3)(tht)] yielding [NBu4][Pt(C6Cl5)3(tht)] and [NBu4][Pd(C6F5)3(tht)], respectively. The reactions between [NBu4]2[Pt(C6F5)4] and [Ag(OCIO3)(tht)] or [Ag(OCIO3)(PPh3)](molar ratio 1:2) render in the first case complex 24 while in the second an unstable material which evolves to [(Ph3P)(C6F5)3PtAg(PPh3)]27 is obtained. The reaction between [NBu4]2[trans-PtCl2(C6X5)2](X = F or Cl) and [Ag(OCIO3)(tht)] or [Ag(tht)2]ClO4 have also been studied. The structures of [(tht)(C6Cl5)(C6F5)2PtAg(PPh3)]14, [NBu4][(C6F5)4PtAg(tht)]24 and [NBu4][cis-(C6Cl5)2PtAg(tht)]25 have been established by single-crystal X-ray diffraction studies. The complexes contain a strong Pt→Ag bond [2.650(2), 14; 2.641(1), 24; and 2.692(2)A, 25] unsupported by covalent bridges, and short contacts between the o-F or o-Cl atoms of the C6X5(X = F or Cl) groups and the Ag atom are present. The relative strength of such contacts is discussed. Methods for the synthesis of mixed pentachloro-pentafluoro-phenyl starting complexes 1–13 have been investigated.

Synthesis of Novel Heterotetrametallic (d6-d10-d8) Polyalkynyl Complexes Starting from Heterobimetallic Chloride-Bridged (d6-d8) Compounds

The reaction between the half-sandwich cyclopentadienyl complexes [M(η5-C5Me5)Cl2(PEt3)] (M = Rh, Ir) and [cis-M′(C6F5)2(thf)2] (M′ = Pt, Pd; thf = tetrahydrofuran) affords the corresponding chloride-bridged heterobinuclear Rh,Ir/Pt,Pd complexes [(PEt3)(η5-C5Me5)M(μ-Cl)2M′(C6F5)2] (1−4). In contrast, similar reactions with the chloro-bridged binuclear compounds [{M(η5-C5Me5)Cl(μ-Cl)}2] (M = Rh, Ir) lead instead to the unexpected mixed salt complexes {Cp*M(μ-Cl)3MCp*}2[{(C6F5)2M′(μ-Cl)}2] (M = Rh, Ir; M′ = Pt, Pd) (5−8) as a result of chloride transfer. The structures of [(PEt3)(η5-C5Me5)Rh(μ-Cl)2Pt(C6F5)2] (1) and {Cp*Rh(μ-Cl)3RhCp*}2[{(C6F5)2Pd(μ-Cl)}2] (6) have been determined by X-ray diffraction analyses. The reactivity of the new chloride-bridged heterobinuclear compounds 1−4 towards the alkynylating agents [M′′(C≡CR)]n (M′′ = Cu, Ag) has also been investigated: a new type of tetranuclear product, [(PEt3)Cp*M(μ-1κCα:η2-C≡CPh)2M′′2(μ-4κCα:η2-C≡CPh)2Pt(C6F5)2] (M = Rh, Ir; M′′ = Cu, Ag) (9−12), was obtained, and fully characterized in the case of complex [(PEt3)Cp*Rh(μ-1κCα:η2-C≡CPh)2Cu2(μ-4κCα:η2-C≡CPh)2Pt(C6F5)2] (9).

SYNTHESIS AND CHARACTERIZATION OF CATIONIC HETERONUCLEAR COMPLEXES OF PLATINUM(II) AND SILVER(I) BRIDGED BY ALKYNYL LIGANDS

Abstract The dialkynyl complexes cis -[Pt(C  CR) 2 L 2 ] [R  Ph, L 2  2PPh 3 , 2PEt 3 , dppe (dppe  1,2-bis(diphenylphosphino)ethane]; R  t Bu, L 2  2PPh 3 , dppe) react with silver perchlorate in a molar ratio 1:0.5 to give platinum-silver perchlorate salts of the type [Pt 2 Ag(C  CR) 4 L 4 ](ClO 4 ) in excellent yield. The X-ray crystal structure of [Pt 2 Ag(C  CPh) 4 (PPh 3 ) 4 ](ClO 4 ) 1 shows that the cation is formed by two nearly orthogonal cis -[Pt(C  CPh) 2 (PPh 3 ) 2 ] units connected through a silver cation which is unsymmetrically π-bonded to all four acetylene fragments. Similar reactions of cis -[Pt(C  CR) 2 L 2 ] with one equivalent of AgClO 4 afford cationic complexes of general formula [PtAg(C  CR) 2 L 2 ](ClO 4 ), which are believed to be salts, [Pt 2 Ag 2 (C  CR) 4 L 4 ](ClO 4 ) 2 .

Unsymmetrical platinum(II) phosphido derivatives: oxidation and reductive coupling processes involving platinum(III) complexes as intermediates.

Reaction of the trinuclear [NBu 4] 2[(R F) 2Pt(mu-PPh 2) 2Pt(mu-PPh 2) 2Pt(R F) 2] ( 1, R F = C 6F 5) with HCl results in the formation of the unusual anionic hexanuclear derivative [NBu 4] 2[{(R F) 2Pt(mu-PPh 2) 2Pt(mu-PPh 2) 2Pt(mu-Cl)} 2] ( 4, 96 e (-) skeleton) through the cleavage of two Pt-C 6F 5 bonds. The reaction of 4 with Tl(acac) yields the trinuclear [NBu 4][(R F) 2Pt(mu-PPh 2) 2Pt(mu-PPh 2) 2Pt(acac)] ( 5, 48 e (-) skeleton), which is oxidized by Ag (+) to form the trinuclear compound [(R F) 2Pt(mu-PPh 2) 2Pt(mu-PPh 2) 2Pt(acac)][ClO 4] ( 6, 46 e (-) skeleton) in mixed oxidation state Pt(III)-Pt(III)-Pt(II), which displays a Pt-Pt bond. The reduction of 6 by [NBu 4][BH 4] gives back 5. The treatment of 6 with Br (-) (1:1 molar ratio) at room temperature gives a mixture of the isomers [(PPh 2R F)(R F)Pt(mu-PPh 2)(mu-Br)Pt(mu-PPh 2) 2Pt(acac)], having Br trans to R F ( 7a) or Br cis to R F ( 7b), which are the result of PPh 2/C 6F 5 reductive coupling. The treatment of 5 with I 2 (1:1 molar ratio) yields the hexanuclear [{(PPh 2R F)(R F)Pt(mu-PPh 2)(mu-I)Pt(mu-PPh 2) 2Pt(mu-I)} 2] ( 8, 96 e (-) skeleton), which is easily transformed into the trinuclear compound [(PPh 2R F)(R F)Pt(mu-PPh 2)(mu-I)Pt(mu-PPh 2) 2Pt(I)(PPh 3)] ( 9, 48 e (-) skeleton). Reaction of [(R F) 2Pt(mu-PPh 2) 2Pt(mu-PPh 2) 2Pt(NCMe) 2] ( 10) with I 2 at 213 K for short reaction times gives the trinuclear platinum derivative [(R F) 2Pt(mu-PPh 2) 2Pt(mu-PPh 2) 2Pt(I) 2] ( 11, 46e skeleton) in mixed oxidation state Pt(III)-Pt(III)-Pt(II) and with a Pt-Pt bond, while the reaction at room temperature and longer reactions times gives 8. The structures of the complexes have been established by multinuclear NMR spectroscopy. In particular, the (195)Pt NMR analysis, carried out also by (19)F- (195)Pt heteronuclear multiple-quantum coherence, revealed an unprecedented shielding of the (195)Pt nuclei upon passing from Pt(II) to Pt(III). The X-ray diffraction structures of complexes 4, 5, 6, 9, and 11 have been studied. A detailed study of the relationship between the complexes has been carried out.

A luminescent polymeric complex containing ten-nuclear platinum-silver ‘[Pt2Ag8(CCBut)8(OClO3)2(acetone)2]+2’, cations in the backbone

Abstract A novel platinum-silver alkynyl polymeric complex {[Pt2Ag8(CCBut)8(OClO3)2(acetone)2](O2ClO2)2}n (2) has been obtained by reaction of [Pt2Ag4(CCBut8] (1) with AgClO4. Its X-ray structure and optical properties (both complexes being luminescent) are reported.

A luminescent Pt3Pb cluster with three Pt(II)→Pb(II) bonds

Abstract The reaction between the pentafluorophenylplatinate derivative (NBu4)2[Pt2(μ-Cl)2(C6F5)4] and Pb(ClO4)2 (1.5:1) in dry tetrahydrofuran yields the tetranuclear complex (NBu4)[Pb{Pt(μ-Cl)(C6F5)2}3] (1). The crystal structure of this compound has been analyzed by X-ray diffraction and reveals the presence of three Pt→Pb metal–metal bonds. This complex shows luminescence at low temperature.

Pentafluorophenyl trinuclear [Pt2Hg] and hexanuclear [Pt4Hg2] anionic complexes containing unbridged PtHg bonds and OH bridges

Abstract Two unprecedented reactions between (NBu 4 ) 2 [Pt(C 6 F 5 ) 4 ] or (NBu 4 ) 2 [Pt(μ-Cl)(C 6 F 5 ) 2 ] 2 and Hg(NO 3 ) 2 lead to trinuclear (NBu 4 ) 2 [(C 6 F 5 ) 3 (μ-OH)(μ-HgC 6 F 5 )Pt(C 6 F 5 ) 3 ] ( 1 ) or hexanuclear (NBu 4 ) 2 [(μ-OH) 2 {(C 6 F 5 ) 2 Pt(μ-OH)(μ-HgCl)Pt(C 6 F 5 ) 2 } 2 ] ( 2 ), respectively. The structures of both complexes have been established by X-ray studies and contain OH bridges between each pair of platinum atoms and donor-acceptor Pt→Hg bonds unsupported by any covalent bridges. The crystallographic parameters are as follows: 1 : monoclinic, C 2/ c with a =19.787(6), b =21.495(6), c =18.242(5) A, β=96.18(3)°, D calc =1.948 g cm −3 for Z =4 formula units and R =0.037 utilizing 3090 data with F o 2 ⩾ 3σ(F o 2 ); 2 : triclinic, P 1 with a =14.23(1), b =17.81(2), c =20.55(2) A, α=87.03(7), β=83.92(7), γ=83.46(5)°, D calc =2.129 g cm −3 for Z =2 and R =0.079 using 6507 reflections with F o 2 ⩾(2.5σ F o 2 ).

Synthesis and characterization of ethylxanthato complexes of zinc(II) with P-donor ligands

Monomeric, five-coordinated bis(ethylxanthato)ZnII(phosphine) complexes [phosphine = PPh3, P(o-tolyl)3, P(CH2Ph)3] have been synthesized by addition of the phosphine ligand (1:1 molar ratio) to CH2Cl2 solutions of [Zn(S2COEt)2]. Bidentate ligands Ph2PCH2CH2PPh2 (dppe) and Ph2P(CH2)4PPh2 (dppb) reacted in a 1:2 molar ratio to form dinuclear phosphine-bridged complexes. The Zn—P bonds are very labile and are probably broken in solution. The characterization of all the compounds has been carried out by elemental analyses and spectroscopic methods (i.r. and n.m.r.). The structure of binuclear [(S2COEt)2Zn(μ-dppb)Zn(S2COEt)2], determined by X-ray crystallography, shows a distorted trigonal bipyramidal environment for the Zn atoms, formed by two chelating xanthate and a bridging dppb ligand.

Dalton communications. Neutral PtAg2 clusters containing unsymmetrical µ3-σ and µ-η2,σ alkynyl groups. Crystal structure of [PtAg2(C6F5)2(µ-η2,σ-CCPh)(µ3-σ-CCPh)(PPh3)2]·0.25CH2Cl2

The reaction between [{PtAg2(C6F5)2(CCR)2}n] and triphenylphosphine in a molar ratio of 1 : 2 has resulted in a good yield of the trinuclear mixed-metal complexes [PtAg2(C6F5)2(µ-η2,σ-CCR)(µ3-σ-CCR)(PPh3)2](R = Ph 3 or But4), and the crystal structure of 3 revealed that they contain two different types of unsymmetrical µ3-σ and µ-η2, σ-edge-bridging alkynyl ligands.