Chelating Phosphine Research Articles

Synthesis, characterisation and photochemistry of platinum diselenolenes

The reaction between [Pt(PPh(3))(4)] and cycloocteno-1,2,3-selenadiazole or bis-cycloocteno-1,4-diselenin in toluene under reflux yielded the poorly soluble mononuclear platinum diselenolene [Pt(Se(2)C(8)H(12))(PPh(3))(2)], 1c. Treatment of [Pt(C(2)H(4))(PR(3))(2)] with a bis-cycloalkeno-1,4-diselenin in a mixture of 1,4-dioxane, THF and toluene under reflux led in good yield to the platinum diselenolenes [Pt(Se(2)C(n+4)H(2n+4))(PR(3))(2)] (R = Et (2), Bu (3); n = 3 (b), 4 (c)). The analogous complexes [Pt(Se(2)C(8)H(12))(L)] (L = dppm: 4c; L = dppe: 5c; L = dppp: 6c) were prepared from 1c via ligand exchange with chelating phosphines. All new compounds have been characterised by multinuclear NMR, IR and UV-visible spectroscopy and mass spectrometry, and their luminescence properties have been examined. The molecular structures of [Pt(Se(2)C(7)H(10))(PEt(3))(2)] (2b), [Pt(Se(2)C(8)H(12))(PEt(3))(2)] (2c) and [Pt(Se(2)C(8)H(12))(dppm)] (4c) have been determined by X-ray crystallography.

Pd-catalyzed addition–carbocyclization of α,ω-diynes with H–P(O)R 2 compounds

Chelating phosphines are much higher performing than mono-dentate phosphines in palladium-catalyzed reaction of α,ω-diynes with HP(O)R 1R 2 (R 1,R 2 = Ph, alkoxy) to afford ( E)-3-(phosphorylmethylene)-2-methylcyclopentenes.

Terpyridine Ruthenium-Catalyzed One-Pot Conversion of Aldehydes into Amides

TerpyRu(PPh3)Cl2 is an efficient catalyst for rearranging aldoximes to amides without the need for chelating phosphines or additives as in prior examples. The catalyst is also useful in converting aldehydes into amides in a one-pot process using NaHCO3 as an additive. A mechanism involving nucleophilic attack of deprotonated oxime on an adjacent nitrile is suggested.

Cyclopalladated azido complexes containing C,N-donor (HC∼N = 2-(2′-thienyl)pyridine, azobenzene, 3,3′-dimethyl azobenzene, N,N′-dimethylbenzylamine, 2-phenylpyridine) ligands: reactivity towards organic unsaturated compounds and catalytic properties

Cyclopalladated azido dimers having various C,N-donor ligands, [Pd(mu-N3)(C,N-Ln)]2 (L1H = 2-(2'-thienyl)pyridine; L2H = azobenzene; L3H = 3,3'-dimethylazobenzene; L4H = N,N'-dimethylbenzylamine; L5H = 2-phenylpyridine), underwent cleavage with tertiary (or chelating) phosphines to form the cyclopalladated [Pd(N3)(PR3)(C,N-L)], the sigma-bonded [Pd(N3)(PR3)2(C-L)], or the dinuclear-cyclopalladated [PdN3(PR3)(C,N-L)]2(mu-P approximately P) complexes. In particular, treating [Pd(mu-N3)(C,N-L)]2 with the basic chelating phosphine (depe or dmpe) produced the homoleptic bis(chelating) complex [Pd(C,N-Ln)2] (n = 1-3). Complex [Pd(N3)(PR3)(C,N-L4)] or [Pd(N3)(PR3)2(C-L4)] reacted with aryl isocyanides to selectively give the imidoyl [Pd(N3)(-C=N-Ar)(PR3)(N-L4)] or the imidoyl carbodiimido complex [Pd(N=C=N-Ar)(-C=N-Ar)(PR3)(N-L4)], which was formed by the CN-Ar insertion into the orthometallated Pd-C bond on the phenyl moiety or the interaction into the Pd-N3 bond of the supporting ligand. In addition, reactions of [Pd(N3)(PR3)2(C-Ln)] (n = 1, 2, 4) with R-NCS {R = i-Pr, C6H4-NCS, (CH3)3Si} gave the S-coordinated tetrazole-thiolato Pd(II) complexes. Finally, the catalytic activity of the cyclopalladated azido complexes was evaluated.

Mono(cyclopentadienyl)titanium(II) Complexes with Hydride, Alkyl, and Tetrahydroborate Ligands: Synthesis, Crystal Structures, and Ethylene Dimerization and Trimerization Catalysis

The mono(cyclopentadienyl)titanium(II) complex CpTiCl(dmpe)2 has been prepared by treating (CpTiCl2)x with n-butyllithium in the presence of 1,2-bis(dimethylphosphino)ethane (dmpe). Subsequent treatment of this titanium(II) species with methyllithium or n-butyllithium affords the alkyl and hydride analogues CpTiMe(dmpe)2 and CpTiH(dmpe)2, respectively. The X-ray crystal structures of CpTiX(dmpe)2 (X = Cl, Me, H) have been determined, and all possess unusually long metal−ligand distances owing to steric crowding in the first coordination sphere of these formally eight-coordinate complexes. Analogous treatment of [Cp*Ti(BH4)Cl]2 with n-butyllithium in the presence of a chelating phosphine affords the mono(pentamethylcyclopentadienyl)titanium(II) complexes Cp*Ti(BH4)(η2-PP), where PP is dmpe or (tert-butyl)tris(dimethylphosphinomethyl)silane (trimpsi). All of these titanium(II) complexes are catalysts for the oligomerization of alkenes. For example, ethylene is dimerized to 1-butene; subsequent coupling reac...

A new coordination mode for tris(2-carboxyethyl)phosphine: Synthesis, crystal structure and characterization of the mixed-valence Co(III)/Co(II)/Co(III) complex [Co{P(CH 2CH 2COO) 2(CH 2CH 2COOH)} 2] 2[Co(H 2O) 4][Na 2(H 2O) 4]Cl 2 · 6H 2O

The water-soluble chelating phosphine ligand tris(2-carboxyethyl)phosphine (TCEP) reacts with cobalt(II) chloride in water to give the mixed-valence Co(III)/Co(II)/Co(III) complex [Co{P(CH 2CH 2COO) 2(CH 2CH 2COOH)} 2] 2[Co(H 2O) 4][Na 2(H 2O) 4]Cl 2 · 6H 2O ( 1). Structural analysis of 1 using single-crystal X-ray diffraction reveals a trimetallic sodium bridged structure in which TCEP adopts a tridentate chelating mode towards Co(III), and a bridging mode towards Co(II) and Na ions.

Active Carbon Functionalized with Chelating Phosphine Groups for the Grafting of Model Ru and Pd Coordination Compounds

An active carbon support has been functionalized in order to introduce at its surface chelating phosphine groups. This has been done in several steps, which have each been studied in detail and optimized in turn. The first step consisted of increasing the number of oxygenated surface groups by oxidative treatment with HNO3. The second step involved the coupling of an amine with the surface carboxylic groups by formation of an amide bond. Various coupling agents were studied, of which SOCl2 was found to be the most efficient. Fluorinated and brominated amines were used as model amines (easier surface quantification by XPS thanks to the presence of heteroatoms such as F or Br), before reacting ethylenediamine. The pending arm of the diamine could then be further transformed into the desired bidentate phosphine in the last step. The success of the procedure was confirmed, and proof for actual surface chemical reactions was obtained. Two coordination compounds, Pd(dba)(2) and Ru-3(CO)(12), were then incorporated on the starting carbon support and on the functionalized one. It was found that the presence of chelating phosphine groups at the surface of the functionalized support allowed to increase the yield of incorporation and the metallic dispersion at the surface, probably via a ligand exchange mechanism. Nanometer-sized Pd and Ru particles were evidenced by TEM.

Rational Design of Chelating Phosphine Functionalized Os(II) Emitters and Fabrication of Orange Polymer Light‐Emitting Diodes Using Solution Process

AbstractA new series of charge neutral Os(II) pyridyl azolate complexes with either bis(diphenylphosphino)methane (dppm) or cis‐1,2‐bis(diphenylphosphino)ethene (dppee) chelates were synthesized, and their structural, electrochemical, photophysical properties and thermodynamic relationship were established. For the dppm derivatives 3a and 4a, the pyridyl azolate chromophores adopt an eclipse orientation with both azolate segments aligned trans to each other, and with the pyridyl groups resided the sites that are opposite to the phosphorus atoms. In sharp contrast, the reactions with dppee ligand gave rise to the formation of two structural isomers for all three kind of azole chromophores, with both azolate or neutral heterocycles (i.e., pyridyl or isoquinolinyl fragments) located at the mutual trans‐disposition around the Os metal (denoted as series of a and b complexes). These chelating phosphines Os(II) complexes show remarkably high thermal stability, among which and several exhibit nearly unitary phosphorescence yield in deaerated solution at RT. A polymer light‐emitting device (PLED) prepared using 0.4 mol % of 5a as dopant in a blend of poly(vinylcarbazole) (PVK) and 30 wt % of 2‐tert‐butylphenyl‐5‐biphenyl‐1,3,4‐oxadiazole (PBD) exhibits yellow emission with brightness of 7208 cd m–2, an external quantum efficiency of 10.4 % and luminous efficiency of 36.1 cd A–1 at current density of 20 mA cm–2. Upon changing to 1.6 mol % of 6a, the result showed even better brightness of 9212 cd m–2, external quantum efficiency of 12.5 % and luminous efficiency of 46.1 cd A–1 at 20 mA cm–2, while the max. external quantum efficiency of both devices reaches as high as 11.7 % and 13.3 %, respectively. The high PL quantum efficiency, non‐ionic nature, and short radiative lifetime are believed to be the determining factors for this unprecedented achievement.

Nickel−Cysteine Binding Supported by Phosphine Chelates

The effect of chelating phosphines was tested on the structure and pH-dependent stability of nickel-cysteine binding. (1,2-Bis(diphenylphosphino)ethane (dppe) and 1,1,1-tris[(diphenylphosphino)methyl]ethane (triphos) were used with three different cysteine derivatives (L-cysteine, Cys; L-cysteine ethyl ester, CysEt; cystamine, CysAm) to prepare complexes of the form (dppe)NiCysR(n+) and (triphos)NiCysR(n+) (n = 0 for Cys; n = 1 for CysEt and CysAm). Similar 31P {1H} NMR spectra for all (dppe)NiCysRn+ confirmed their square-planar P2NiSN coordination spheres. The structure of [(dppe)NiCysAm]PF6 was also confirmed by single-crystal X-ray diffraction methods. The (triphos)NiCysAm+ and (triphos)NiCysEt+ complexes were fluxional at room temperature by 31P NMR. Upon cooling to -80 degrees C, all gave spectra consistent with a P2NiSN coordination sphere with the third phosphorus uncoordinated. Temperature-dependent 31P NMR spectra showed that a trans P-Ni-S pi interaction controlled the scrambling of the coordinated triphos. In aqueous media, (dppe)NiCys was protonated at pH approximately 4-5, leading to possible formation of a nickel-cysteinethiol and eventual cysteine loss at pH < 3. The importance of N-terminus cysteine in such complexes was demonstrated by preparing (dppe)NiCys-bead and trigonal-bipyramidal Tp*NiCys-bead complexes, where Cys-bead represents cysteine anchored to polystyrene synthesis beads and Tp*- = hydrotris(3,5-dimethylpyrazolyl)borate. Importantly, results with these heterogeneous systems demonstrated the selectivity of these nickel centers for cysteine over methionine and serine and most specifically for N-terminus cysteine. The role of Ni-S pi bonding in nickel-cysteine geometries will be discussed, including how these results suggest a mechanism for the movement of electron density from nickel onto the backbone of coordinated cysteine.

Group 8 and 10 hyponitrite and dinitrosyl complexes

cis-Hyponitrite complexes L n M(N 2O 2) (M = Ni, Pt; L n = PPh 3, PPh 2Me, dppe, and dppf) of divalent group 10 metals have been previously shown to be readily prepared by treating the corresponding L n MCl 2 derivatives with sodium-( Z)-1-{4-(2,6-di- tert-butyl-4-methoxycyclohexadienonyl)}diazen-1-ium-1,2-diolate. These complexes adopt a diamagnetic square planar geometry with oxygen bound chelating planar cis-hyponitrite ligands. They are readily prepared at room temperature but thermally decompose above 90 °C with release of nitrous oxide. Electrophiles such as iodine, methyltriflate, and hydrochloric acid also react rapidly with the cis-hyponitrite complexes to give nitrous oxide. The structure of one of these previously prepared complexes, (PPh 3) 2Pt(N 2O 2), has been redetermined at −100 °C as a dichloromethane solvate with improved precision. The related tetrahedral group 8 dinitrosyl complexes, (PPh 3) 2M(NO) 2 (M = Ru, Os; L n = PPh 3, dppe, and dppf) have been reexamined and new derivatives with chelating phosphines have been prepared by ligand substitution on the corresponding (PPh 3) 2M(NO) 2. The structures of Ru(dppf)(NO) 2 and Os(dppe)(NO) 2 have been determined. These two analogous families of cis-hyponitrite and dinitrosyl complexes illustrate the balance of metal d n electron count and nitrosyl redox state with one having linear nitrosyls bound to low valent metal centers, and the former having coupled N 2 O 2 2 - ligands bound to a higher oxidation state metal center.

Transition Metal-Catalyzed Organometallic Reactions that Have Revolutionized Organic Synthesis

Abstract The Pd- or Ni-catalyzed cross-coupling reactions of organometals containing Zn, Al, Zr, and B as well as related reactions of Mg and several other metals collectively represent the most widely applicable organic skeleton construction method discovered and developed over the past several decades, allowing the synthetic chemists to synthesize practically all types of organic compounds. Some of the seminal and critically important discoveries and early developments in the 1970s as well as their current scope (Tables 2 and 3) are briefly discussed. Some of the notable discoveries and developments include (1) identification of superior properties of Pd relative to Ni, (2) the broad scope of Pd- or Ni-catalyzed cross-coupling with respect to metal counter cations including Zn, Al, Zr, B, and Mg, (3) the hydrometallation–Pd-catalyzed cross-coupling tandem processes for selective syntheses of alkenes, dienes, oligoenes, and oligoenynes, (4) double metal catalysis involving Pd or Ni and added metal compounds containing Zn, In, Li, and others, and (5) realization of high turnover numbers (≥103–105) through the use of chelating phosphines, such as DPEphos and dppf. In these reactions, the metal counter cations in organometals and Pd or Ni are to work successively via transmetallation. The Zr-catalyzed alkyne carboalumination and the Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction) have provided efficient and selective routes to methyl-branched (E)-trisubstituted alkenylalanes and 2-substituted chiral alkylalanes, respectively. These reactions provide two additional examples of prototypical transition metal-catalyzed organometallic reactions. Significantly, they can be readily combined with the Pd- or Ni-catalyzed cross-coupling for the synthesis of trisubstituted alkenes embracing a wide variety of natural products, such as terpenoids, carotenoids, and others, as well as various chiral organics including deoxypolypropionates and saturated terpenoids. The Zr-catalyzed alkyne carboalumination has been applied to the synthesis of well over 100 complex natural products (Table 4), while the ZACA reaction has been transformed from a mere scientific novelty to a full-fledged asymmetric synthetic method that is catalytic in both transition metal (Zr) and chiral auxiliaries through a series of breakthroughs (Schemes 12–17).

Synthesis and electrochemical aspects of group 14 iron complexes of the type (η5-C5H5)Fe(L)2ER3, L2 = (CO)2, (Ph2P)2CH2; E = C, Si, Ge, Sn

The dicarbonyl and diphosphine complexes of the type (η5-C5H5)Fe(L)2ER3 (L2=(CO)2 (a), (Ph2P)2CH2 (b); ER3=CH3 (1a/b); SiMe3 (2a/b), GeMe3 (3a/b), SnMe3 (4a/b)) were synthesized and studied electrochemically. Cyclic voltammetric studies on the dicarbonyl complexes 1a–4a revealed one electron irreversible oxidation processes whereas the same processes for the chelating phosphine series 1b–4b were reversible. The Eox values found for the series 1a–4a were in the narrow range 1.3–1.5V and in the order Si>Sn≈Ge>C; those for 1b–4b (involving replacement of the excellent retrodative π-accepting CO ligands by the superior σ-donor and poorer π-accepting phosphines) have much lower oxidation potentials in the sequence Sn>Si≈Ge>C. This latter oxidation potential pattern relates directly to the solution 31P NMR chemical shift data illustrating that stronger donation lowers the Eox for the complexes; however, simple understanding of the trend must await the results of a current DFT analysis of the systems.

Synthesis of N-heterocyclic carbene palladium(ii) bis-phosphine complexes and their decomposition in the presence of aryl halides

Methylpalladium(II) carbene complexes of the type [Pd(NHC)Me(P-P)]BF(4) (NHC = N-heterocyclic carbene, P-P = chelating phosphine) have been synthesised, the complex [Pd(tmiy)Me(dcype)]BF(4) (tmiy = 1,3,4,5-tetramethylimidazol-2-ylidene, dcype = 1,2-bis(dicyclohexylphosphino)ethane) being characterised crystallographically. Complexes bearing the tmiy ligands were shown to decompose in an analogous manner to complexes bearing monodentate phosphine ligands, with the rate of decomposition being nominally linked to the size of the chelate ring. The decomposition of these complexes in the presence of aryl halides-expected to yield Pd(Ar)X(P-P)-was studied and shown instead to yield PdX(2)(P-P) and [Pd(tmiy)X(P-P)]BF(4). Additionally, Pd(Me)X(P-P) and Pd(Ar)X(P-P) were observed in some cases. Intermolecular cross-over reactions between the starting complex and Pd(Ar)X(P-P) were found to be the source of these unexpected products.

Synthesis and characterization of three nickel(ii) carborane complexes containing nido- or closo-carborane diphosphine ligand

Three nickel(II) carborane complexes, [Ni 2(μ-Cl) 2{7,8-(PPh 2) 2-7,8-C 2B 9H 10} 2] ( 1), [Ni{7-(OPPh 2)-8-(PPh 2)-7,8-C 2B 9H 10}{7,8-(PPh 2) 2-7,8-C 2B 9H 10}] ( 2) and [NiBr 2{1,2-(PPh 2) 2-1,2-C 2B 10H 10}] · CH 2Cl 2 ( 3), have been synthesized by the reactions of 1,2-bis(diphenylphosphino)-1,2-dicarba- closo-dodecaborane with NiCl 2 · 6H 2O or NiBr 2 · 6H 2O in ethanol under different conditions, respectively. For complex 1, it could also be obtained under the solvothermal condition. All the three complexes were characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopy and X-ray structure determination. Single crystal analysis shows that the molecular symmetry of complex 1 is centrosymmetric, containing two same structure units – Ni(7,8-(PPh 2) 2-7,8-C 2B 9H 10) linked by two bridged-Cl atoms. The central square plane formed by the [Ni 2Cl 2] unit is almost parallel to the two side NiPP planes. For complex 2, the coordination environment of the Ni atom is a seriously distorted square-planar, in which two positions come from the chelating diphosphine ligand [7,8-(PPh 2) 2-7,8-C 2B 9H 10] − degraded from the closo species, while the other two are occupied by an unsymmetrical chelating phosphine oxide ligand [7-(OPPh 2)-8-(PPh 2)-7,8-C 2B 9H 10] −. As for complex 3, the geometry at the Ni atom is a slightly distorted square-planar. The closo carborane diphosphine ligand 1,2-(PPh 2) 2-1,2-C 2B 10H 10 was coordinated bidentately to the metal ion through the two phosphorus atoms, and the two Br atoms are at cis position which can fulfill the four coordination mode of the metal.

Synthesis, immobilization, and solid-state NMR of new phosphine linkers with long alkyl chains

Monodentate and chelating phosphines with long alkyl chains, incorporating ethoxy- or chlorosilane functions for immobilizations, have been synthesized and fully characterized. The new compounds (EtO) 3Si(CH 2) x PPh 2, Cl 2Si(CH 2CH 2PPh 2) 2, and (EtO) 2Si[(CH 2) x PPh 2] 2 ( x = 7, 11) could be prepared in high yields from cheap starting materials, and they have been characterized by multinuclear NMR spectroscopy and X-ray crystallography. The phosphines have been immobilized on silica in a well-defined manner, and the modified silicas have been studied by 31P and 29Si solid-state NMR of the dry materials and of the suspensions.

Phosphorus(I) Iodide: A Versatile Metathesis Reagent for the Synthesis of Low Oxidation State Phosphorus Compounds

An improved method for the synthesis of cyclic low oxidation state P cations is presented. The only byproducts of the reaction of phosphorus triiodide with chelating phosphines are readily removed, resulting in an easily accessible P(I) reagent with an anion that can be readily replaced through salt metathesis chemistry. These P(I) salts are surprisingly stable, even in O2 and moisture, and the origin of this unusual stability is elucidated using density functional theory calculations.

Synthesis and Coordination Chemistry of a Novel Bidentate Phosphine: 6-(Diphenylphosphino)-1,3,5-triaza-7-phosphaadamantane (PTA-PPh2)

The upper rim of 1,3,5-triaza-7-phosphaadamantane (PTA) has been modified for the first time. Lithiation of PTA, with n-butyllithium, resulted in deprotonation of an alpha-phosphorus methylene and the formation of 1,3,5-triaza-7-phosphaadamantane-6-yllithium (PTA-Li). The chiral chelating phosphine 6-(diphenylphosphino)-1,3,5-triaza-7-phosphaadamantane (PTA-PPh2) was synthesized, in racemic form, by the reaction of PTA-Li with ClPPh2. PTA-PPh2 has been fully characterized in solution by multinuclear NMR spectroscopy and mass spectrometry and in the solid state by X-ray crystallography. The 31P NMR spectrum contains a pair of doublets at -19.8 and -100.1 ppm (d, (2)J(PP) = 65 Hz). Unlike PTA, the new bidentate phosphine, PTA-PPh2, is insoluble in aqueous solutions. Two group 6 metal carbonyl complexes, [M(CO)4(PTA-PPh2)] (M = W and Mo), were synthesized by the addition of PTA-PPh2 to cis-[M(CO)4(pip)2] and characterized by NMR spectroscopy, IR spectroscopy, and X-ray crystallography. Also reported are the solid-state structures of cis-[W(CO)4PTA2], cis-[W(CO)4(PTA)(PPh3)], and [W(CO)4DPPM] (DPPM = diphenylphosphinomethane). PTA-PPh2 appears to be sterically similar to and slightly more electron-donating than DPPM.

Divalent Germanium and Tin Compounds Stabilized by Sterically Bulky P∧O, PO∧O, PS∧O, and PN∧O Ligands: Synthesis and First Insights into Catalytic Application to Polyurethane Systems

A sterically bulky chelating phosphine, t Bu 2 P-CH 2 -C(CF 3 ) 2 OH (1), was shown to stabilize divalent tin and germanium compounds: M[-O-C(CF 3 ) 2 CH 2 P t Bu 2 ] 2 (6, M = Sn; 14, M = Ge). Oxidizing reagents, e.g., sulfur, pyridine-N-oxide, and 1-azidoadamantane, reacted with divalent tin 6 on the phosphorus ligands exclusively, preserving the divalent state of tin in the resultant compounds Sn[-O-C(CF 3 ) 2 -CH 2 P(S) t Bu 2 ] 2 (7), Sn[-O-C(CF 3 ) 2 CH 2 P(O) t Bu 2 ] 2 (11) and Sn[-O-C(CF 3 ) 2 CH 2 P t Bu 2 ],[-O-C(CF 3 ) 2 -CH 2 P(N 3 -Adamantyl) t Bu 2 ] 2 (12). The divalent germanium compound 14 was found to be more prone to oxidation to the tetravalent state. For example, the reaction with 1-azidoadamantane gave tetravalent germanium compounds Ge[-O-C(CF3) 2 CH 2 P(-) t Bu],[-O-C(CF 3 ) 2 CH 2 P(=N-) t Bu 2 ] (16) and [Adaman-tyl],[-O-C(CF 3 ) 2 CH 2 P(=N-)]Ge-O-Ge[-O-C(CF 3 ) 2 CH 2 P(tBu) 2 (=N-)],[Adamantyl] (17). A Ge-O-Ge bridge in 17 is very linear, with an angle Ge-O-Ge of 177.4(2)°. According to X-ray analyses the intramolecular M-P bond lengths are among the longest known for this kind of bonding: 3.228(4) A for P-Sn in 12 and 2.7585(12) A for P-Ge in 14. The divalent tin compounds 6 and 7 were found to be efficient catalysts for the formation of polyurethanes. The divalent germanium compound 14 was active in polyurethane formation, but it was an order of magnitude less active than corresponding tin analogue 6.

Preparation of a series of novel fluorophores, N-substituted 6-amino and 6,6″-diamino-2,2′:6′,2″-terpyridine by palladium-catalyzed amination

A new series of N-substituted 6-amino- and 6,6″-diamino-2,2′:6′,2″-terpyridine (6-amino- and 6,6″-diamino-tpy) was conveniently synthesized in one-step by Pd-catalyzed amination of bromo-substituted tpys with various amines. For highly coordinating tpy substrates, use of appropriate chelating phosphine ligand was critical to achieve moderate to satisfactory yield. The prepared N-substituted 6-amino- and 6,6″-diamino-tpys exhibited moderate to intense fluorescence in dichloromethane with fine-tuned fluorescence maxima ranging from 385 to 455 nm.

Synthesis, structure, immobilization and solid-state NMR of new dppp- and tripod-type chelate linkers

Chelating phosphines incorporating ethoxysilane functions for immobilizations have been synthesized and fully characterized. (EtO)Si(CH2PPh2)3, (EtO)2Si(CH2PPh2)2, and Si(CH2PPh2)4 could be prepared in high yields from cheap starting materials. The ethoxysilanes, as well as a Pd complex thereof have been characterized by X-ray structures, and immobilized on silica. The success of the immobilization was proved by 31P solid-state NMR of the dry materials and of the suspensions. Two representative chelate metal complexes, (EtO)2Si(CH2PPh2)2PdCl2 and (EtO)Si(CH2PPh2)3W(CO)3 have been synthesized, characterized and immobilized.