Claudia Graiff

Blue-emitting dinuclear N-heterocyclic dicarbene gold(I) complex featuring a nearly unit quantum yield.

Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au(2)(RIm-Y-ImR)(2)](PF(6))(2) (R = Me, Cy; Y = (CH(2))(1-4), o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me, Y = (CH(2))(3) exhibit an intense blue emission (λ(max) = 450 nm) with a high quantum yield (Φ(em) = 0.96). The X-ray crystal structure of this complex is characterized by a rather short intramolecular Au···Au distance (3.272 Ǻ). Time dependent density functional theory (TDDFT) calculations have been used to calculate the UV/vis properties of the ground state as well as of the first excited state of the complex, the latter featuring a significantly shorter Au···Au distance.

Chiral Phosphoramidite Ligands Based on 8‐Chloroquinoline and Their Rhodium(III), Palladium(II), and Platinum(II) Complexes

The new chiral ligands 2-butyl-8-chloro-1-(4,8-di-tert-butyl-2,10-dimethoxy-5,7-dioxa-6-phosphadibenzo[a,c]cyclohepten-6-yl)-1,2-dihydroquinoline (BIPHENPHOSHQUIN, 3) and 2-butyl-8-chloro-1-(3,5-dioxa-4-phosphacyclohepta[2,1-a;3,4-a′]dinaphthalen-4-yl)-1,2-dihydroquinoline (BINAPHOSHQUIN, 4; 4a: SaRC, 4b: SaSC) have been synthesized starting from the rigid backbone of 8-chloroquinoline. The reactions of 3 and 4 with rhodium(I), palladium(II), and platinum(II) substrates are reported. The reaction of 3 with [Rh(CO)2Cl]2 in a 2:1 molar ratio in hexane afforded a binuclear chloro-bridged rhodium(III) species by intramolecular oxidative addition of the C–Cl bond of ligand 3 across the rhodium(I) centers. The rhodium(III) complex 5, incorporating the enantiomers SaRC-3 and RaSC-3, has been fully characterized by X-ray diffractometry. Reactions of [Pd(PhCN)2Cl2] with the ligands 3 and 4a in 1:2 molar ratio in toluene afforded the products cis-[Pd(3)2Cl2] (9) and cis-[Pd(4a)2Cl2] (10). Similarly, reaction of [Pt(COD)I2] with 4a in a 1:2 molar ratio afforded the complex cis-[Pt(4a)2I2] (11). An X-ray analysis has been carried out to obtain information on the effect of the ligand 4a on the overall structure of 11.

Topologically Unique Heterometallic CuII/Li Coordination Polymers Self-Assembled from N,N-bis(2-Hydroxyethyl)-2-aminoethanesulfonic Acid Biobuffer: Versatile Catalyst Precursors for Mild Hydrocarboxylation of Alkanes to Carboxylic Acids

The facile aqueous medium reactions of copper(II) nitrate with BES biobuffer [(HOCH(2)CH(2))(2)N(CH(2)CH(2)SO(3)H), hereinafter referred as H(3)bes] in the presence of various benzenecarboxylic acids [benzoic (Hba), 3-hydroxybenzoic (Hhba), and 3,5-dihydroxybenzoic (Hdhba) acid] and lithium hydroxide gave rise to the self-assembly generation of three new heterometallic Cu(II)/Li materials, [Li(H(2)O)(4)][Cu(4)(μ(2)-Hbes)(4)(μ(2)-ba)]·H(2)O (1) and [Cu(4)(μ(3)-Hbes)(4)(L){Li(H(2)O)(2)}](n)·3nH(2)O {L = μ(2)-hba (2) and μ(2)-dhba (3)}. They were isolated as air-stable crystalline solids and fully characterized by infrared (IR) and UV-vis spectroscopy and electrospray ionization (ESI)-MS(±), elemental, thermal, and single-crystal X-ray diffraction analyses. The latter revealed that 1-3 have comparable packing patterns and unit cell parameters, being composed of similar [Cu(4)(μ-Hbes)(4)(μ-carboxylate)](-) cores and [Li(H(2)O)(4)](+) cations (in 1) or [μ-Li(H(2)O)(2)](+) groups (in 2 and 3), which are arranged into discrete 0D aggregates in 1 or infinite 3D noninterpenetrating metal-organic networks in 2 and 3. The topological analysis of the coordination polymers 2 and 3 disclosed the trinodal 3,3,4-connected underlying nets with an unprecedented topology defined by the point symbol of (4.6.8)(4)(4(2).6)(2)(6(2).16(2).18(2)), further simplification of which resulted in the binodal 4,4-connected nets with the pts (PtS) topology. Apart from representing very rare examples of coordination compounds derived from H(3)bes, 1-3 feature solubility in water and were applied as efficient and versatile catalyst precursors for the mild (60 °C) single-pot hydrocarboxylation, by CO and H(2)O, of various gaseous, linear, and cyclic C(n) (n = 2-9) alkanes into the corresponding C(n+1) carboxylic acids, in H(2)O/MeCN medium under homogeneous conditions and in the presence of potassium peroxodisulfate. Total yields (based on alkane) of carboxylic acids up to 78% were achieved, which are remarkable in the field of alkane functionalization under mild conditions, especially for a C-C bond formation reaction in aqueous acid-solvent-free medium.

Self-assembly of polyoxoselenitopalladate nanostars [Pd15(μ3-SeO3)10(μ3-O)10Na]9− and their supramolecular pairing in the solid state

An anionic Pd₁₅-oxo-cluster [Pd₁₅(μ₃-SeO₃)₁₀(μ₃-O)₁₀Na]⁹⁻ has been synthesized. It is the result of an unprecedented self-assembly of Pd(2+) and Na(+) cations, SeO₃²⁻ and oxo anions. It has been found for the first time, that selenito groups can give rise to supramolecular interactions in the solid state with palladium atoms, through the selenium electron lone pairs.

Ring-Opening of Lawesson’s Reagent: New Syntheses of Phosphono- and Amidophosphono-Dithioato Complexes − Structural and CP-MAS31P-NMR Characterization of [p-CH3OPh(X)PS2]2M (X = MeO,iPrNH; M = NiII, PdII, and PtII)

The opening of the P2S2 tetraatomic ring of Lawesson’s reagent (4) has proved versatile in synthesizing phosphono- and amidophosphono-dithioato mononuclear complexes [p-CH3OPh(X)PS2]2M [X = CH3O, iPrNH; M = NiII, PdII, PtII]. A one-step reaction of 4 with the appropriate metal salt in CH3OH, or in the presence of a stoichiometric amount of iPrNH2 in CHCl3, is used in the direct synthesis of the NiII and PdII complexes, but does not work in the PtII complexes. Alternatively, these syntheses can be carried out: i) by preparation and isolation of O-methyl(4-methoxyphenyl)phosphonodithioate (6) salts or isopropylamido(4-methoxyphenyl)- phosphonodithioate (7) salts by treating 4 with CH3O− in CH3OH or with iPrNH2, respectively; ii) by reaction of 6 or 7 with MCl2 or K2MCl4 [M = NiII, PdII, PtII] to give trans-bis[O-methyl(4-methoxyphenyl)phosphonodithioato]M and trans-bis[isopropylamido(4-methoxyphenyl)phosphonodithioato]M complexes. Following these routes, trans-bis[O-methyl(4-methoxyphenyl)phosphonodithioato]M [M = Ni (8a), Pd (8b), and Pt (8c)] and trans-bis[isopropylamido(4-methoxyphenyl)phosphonodithioato]M [M = Ni (9a), Pd (9b), and Pt (9c)] complexes have been synthesized and fully characterized by FAB mass, FT-IR, FT-Raman, UV/Vis, and CP-MAS 31P-NMR spectroscopy; the crystal structures of 7, 8b, 8c, and 9a are also reported.

One-step syntheses of Ph3P-substituted selenido carbonyl iron and ruthenium clusters Part 2. Crystal structures of Fe2(μ2-Se2)(CO)6-n(PPh3)n(n=1 or 2) Fe3(μ3-Se)2(CO)8(PPh3) and Ru4(μ4-Se)2(μ-CO)2(CO)8(PPh3), and HPLC behaviour of the iron derivatives

Abstract Ph 3 PSe reacts with Fe 3 (CO) 12 giving six products ( 1–6 ) belonging to three different families of clusters: Fe 3 (μ-Se 2 )(CO) 9- n L n (two products, 3,5 , n = 1, 2, Fe 3 ( μ 3 -Se) 2 (CO) 9- n L n (three products, 1, 2, 4 , n = 0–2) and Fe 3 -Se)( μ - CO ) 9- n L n (one product, 6 , n = 2). Under the same conditions, Ru 3 (CO) 12 affords Fe 3 (μ 3 -Se) 2 (CO) 9- n (PPh 3 ) n (three products 7,8,10 , n = 1–3) and the tetraruthenium clusters Ru 4 (μ 4 -Se) 4 (CO) 2 (CO) 9- n (PPh 3 ) n (two products, 11, 9 , n =1,2). The structures of the clusters 2, 3, 5 and 11 · 1 2 CH 2 Cl 2 have been determined by X-ray diffraction methods. The mass-spectral behaviour of iron mono- and disubstituted phosphine derivatives ( 2–6 ) is characterised by the low abundance (

Synthesis of diphosphine-substituted selenido carbonyl iron clusters: Progressive deformation of the Fe3Se2 core in the nido clusters [Fe3Se2(CO)7μ-(Ph2P)2R] by widening the bite of the bridging ligand

Abstract The reactions of [Fe 3 (CO) 12 ] with three diphosphine diselenides, dppmSe 2 , dppeSe 2 and dppfcSe 2 , produce the disubstituted clusters [Fe 3 (μ 3 -Se) 2 (CO) 7 (Ph 2 P) 2 R] (R = CH 2 (dppm) 3 ; R = CH 2 CH 2 (dppe) 7 ; R = (C 5 H 4 ) 2 Fe (dppfc) 8 ) as the main products. Other products are [Fe 3 (μ 3 Se) 2 (CO) 9 ] 1 , [Fe(CO) 4 (dppm)] 2 , [Fe 2 (μ-Se 2 )(CO) 4 (dppm)] 4 in the case of dppm and [Fe 3 (μ 3 -Se) 2 (CO) 8 2 (dppe)] 5 in the case of dppe. Clusters 1, 3, 5, 7 and 8 have a square-pyramidal structure with two iron and two selenium atoms alternating in the basal plane and the third iron atom (Fe ap ) at the apex of the pyramid, and should be regarded as nido -clusters with seven skeletal electron pairs. The phosphine substitution is regioselective, occurring only on the two basal iron atoms. 1 H and 31 P NMR data in solution suggest a fluxional behaviour for 3 and 7 in solution due to the migration of a metal-metal bond to link the two iron atoms bound to the bidentate ligand. This is probably related to the deformation of the Fe 3 Se 2 core induced by the steric demand of the diphosphines in such a way that the Fe ⋯ Fe non-bonding distance decreases as the bite of the ligand shortens. The crystal structures of 3, 4, 5, 7 and 8 are described.

Rhodium(I), Palladium(II), and Platinum(II) Complexes Containing New Mixed Phosphane−Phosphite Ligands − Effect of the Catalytic System Stability on the Enantioselective Hydroformylation of Styrene

The new mixed phosphane−phosphite ligands 1 and 2, derived from 3,3′-di-tert-butyl-2,2′-dihydroxy-5,5′-dimethoxybiphenyl and (S)-binaphthol, respectively, reacted with [Rh(COD)(THF)2]CF3SO3 to give the compounds [Rh(COD)(1)]CF3SO3 and [Rh(COD)(2)]CF3SO3 in which the ligands 1 and (S)-2 are chelated to the rhodium centre. The reaction with [Rh(CO)2Cl]2 gave two different products, [Rh(CO)2(L)Cl] and [Rh(CO)(L)Cl] [L = 1 and (S)-2], containing L as a chelate. On the basis of the IR and NMR spectroscopic data, the proposed structure of the pentacoordinate species is a trigonal bipyramide in which the phosphane−phosphite ligand assumes an equatorial-axial coordination. The reactions of 1 and 2 with [Pd(C6H5CN)2Cl2] and [Pt(COD)I2] gave the corresponding compounds [Pd(L)Cl2] and [Pt(L)I2] in which the ligands are chelated to the metal centre. The crystal structure of the chloroform solvate of [Pd(L)Cl2] was fully characterised by an X-ray study. The chiral ligands (S)-2 and (S)-3 [derived from the ortho-bis(trimethylsilyl)-substituted (S)-binaphthol] were tested in the hydroformylation of styrene. The results obtained were discussed in light of the catalytic system stability.

Synthesis of Phosphonito,N and Phosphito,N ligands based on quinolines and (R)-binaphthol or substituted biphenol and of their rhodium(I), palladium(II) and platinum(II) complexes

Abstract The new Phosphonito,N ligands 8-(4,8-di-tert-butyl-1,11-dimethoxy-5,7-dioxa-6-phospha-dibenzo[a,c]cyclohepten-6-yl)-quinoline (2a), and (R)-8-(3,5-dioxa-4-phospha-cyclohepta-[2,1-a;3,4-a′]dinaphthalen-4-yl)-quinoline ((R)-2b), were readily prepared starting from 8-(bis-diethylamino-phosphine)-quinoline (1), as a key intermediate, and 2,2′-dihydroxy-5,5′-dimethoxy-3,3′-di-tert-butylbiphenyl or (R)-binaphthol, respectively. The Phosphito,N ligand, 8-(4,8-di-tert-butyl-1,11-dimethoxy-5,7-dioxa-6-phospha-dibenzo[a,c]cyclohepten-6-yloxy)-quinoline (3a), was obtained by reacting equimolar amounts of 8-hydroxyquinoline and the phosphorochloridite derived from 3,3′-di-tert-butyl-2,2′-dihydroxy-5,5′-dimethoxybiphenyl, in toluene in the presence of NEt3. The corresponding Phosphito,N-ligand, 8-(3,5-dioxa-4-phospha-cyclohepta[2,1-a;3,4-a′]dinaphthalen-4-yloxy)-quinoline (R)-(3b), was obtained similarly using the phosphorochloridite derived from (R)-binaphthol. A systematic study of the coordination abilities of 2–3 to rhodium(I), palladium(II) and platinum(II) precursors has been carried out. Crystal structures of the complexes [Pt(3a)I2] (7a), and [Pd(2a)Cl2] (8a), are reported. The reactions of the chiral ligands (R)-2b and (R)-3b with [Rh(acac)(CO)2] lead to [Rh(acac)(R-2b)] (10), and [Rh(acac)(R-3b)] (11), respectively. Under hydroformylation conditions, displacement of the chiral ligands in both complexes 10 and 11 takes place, even in the presence of an excess of free ligand, leading to achiral hydrido-carbonyl rhodium complexes.

New trisubstituted cyclopentadienyl ligands: synthesis, characterisation and catalytic properties of mono and dinuclear cobalt, rhodium, iron and ruthenium complexes

Abstract The synthesis of a set of dialkyl 4-alkoxycarbonylcyclopenta-1,3-diene-1,2-diacetates (1a–e) is described. Their coordinating abilities as anions have been investigated in relation to the formation of new sandwich, half-sandwich and dinuclear complexes and their structural features. We report here the preparation and characterisation of some complexes such as a mononuclear half-sandwich cobalt(1,5-COD) complex which has shown to be a very efficient catalyst for the cyclocotrimerisation reaction of alkynes and nitriles to pyridines. Half-sandwich rhodiumdicarbonyl complexes containing trisubstituted cyclopentadienyl ligands with ester chains of different length have been employed successfully as catalysts for hydroformylation of styrene. Finally ligands 1a–e have been used for the synthesis of ferrocenes and dinuclear carbonyl complexes of iron and ruthenium. The structures of the complexes 1,5-cycloctadiene[1-methoxycarbonyl-3,4-di(methoxycarbonylmethylene)cyclopentadienyl]cobalt [Co(MDMCp)COD] (9), dicarbonyl[1-methoxycarbonyl-3,4-di(methoxycarbonylmethylene)cyclopentadienyl]rhodium [Rh(MDMCp)(CO)2] (2a) and of a new ferrocene complex [Fe(MDMCp)2] (15a) have been determined by X-ray diffraction methods.