The investigation of stereogenic properties of cyclotriphosphazene derivatives with two different chiral centres

Hexachlorocyclotriphosphazene N₃P₃Cl₆ and gem-disubstituted cyclotriphosphazene derivatives N₃P₃Cl₄X₂ (X = Ph, PhS, PhNH) were reacted with N-methyl-1,3-propanediamine and 3-amino-1-propanol to give compounds (9a-12a, 9b-12b) which exist as cis and trans geometric isomers and are two different racemic isomers, respectively to describe the stereogenic properties of a series of chiral cyclotriphosphazene compounds with two different centres of chirality. The geometric isomers were separated by column chromatography on silica gel and analysed by elemental analysis, mass spectrometry, and ³¹P and ¹H NMR spectroscopies, and also the geometric forms (cis or trans) of 9b, 10a, 11a, 11b and 12a have been determined by the X-ray crystallography. The enantiomers of all racemic compounds have been analysed by the changes in ³¹P NMR spectra on addition of a Chiral Solvating Agent (CSA), (R)-(+)-2,2,2-trifluoro-1-(9′-anthryl)ethanol. On the other hand, the racemic forms of chiral cyclotriphosphazene derivatives have been confirmed by contribution of chiral HPLC methods which have been developed for this study.     

Half-sandwich η-arene–ruthenium(II) complexes bearing 1-alkyl(benzyl)-imidazo[4,5-f][1,10]-phenanthroline (IP) derivatives: the effect of alkyl chain length of ligands to catalytic activity

The reaction of bromoalkanes (R–Br; (3), R=C_nH_2n+1, n=4 (a), 8 (b), 12 (c),18 (d)) and bromobenzyl derivatives (R′–Br; (4), R′=CH₂C₆H₂(CH₃)₃-2,4,6 (a); CH₂C₆H(CH₃)₄-2,3,5,6 (b); CH₂C₆(CH₃)₅ (c)) with 1H-imidazo[4,5-f][1,10]-phenanthroline (IP)(L₂) gave the corresponding 1-R-imidazo[4,5-f][1,10]-phenanthroline (IPR)(L_3a–d) and 1-R′-imidazo[4,5-f][1,10]-phenanthroline(IPR')(L_4a–c) ligands, respectively. Treatment of L_3a–d and L_4a–d with [Ru(p-cymene)Cl₂]₂ led to the formation of [Ru(p-cymene)(IPR)Cl]Cl (RuL_3a–d) and [Ru(p-cymene)(IPR′)Cl]Cl (RuL_4a–c). New ruthenium(II) complexes RuL_3a–d and RuL_4a–c were characterized by elemental analysis, FTIR, UV–visible and NMR spectroscopy. In order to understand effects of these changes on the N-substituent of imidazol on IP and how they translate to catalytic activity, these new RuL₂, RuL_3a–d and RuL_4a–c were applied in the transfer hydrogenation of ketones by 2-propanol in presence of potassium hydroxide. The activities of the catalysts were monitored by NMR and GC analysis.     

Synthesis and characterization of new oxazoline-based palladacycles with bridging or terminal imidate ligands. Crystal structures of [{Pd(μ-dibromomaleimidate)(Phox)}2], [Pd(dibromomaleimidate)(Phox)(PPh3)] and [Pd(glutarimidate)(Phox)(PPh3)] (Phox = 2-(2-oxazolinyl)phenyl))

The dinuclear hydroxo complex [{Pd(μ-OH)(Phox)}₂] (I) (Phox = 2-(2-oxazolinyl)phenyl) reacts in a 1:2 molar ratio with several imidate ligands to yield new cyclometallated palladium complexes [{Pd(μ-NCO)(Phox)}₂] containing asymmetric imidate –NCO– bridging units. [–NCO– = succinimidate (succ) (1), phtalimidate (phtal) (2), maleimidate (mal) (3), 2,3-dibromomaleimidate (2,3-diBrmal) (4) and glutarimidate (glut) (5)]. The reaction of these complexes with tertiary phosphines provides novel mononuclear N-bonded imidate derivatives of the general formula [Pd(imidate)(Phox)(PR₃)] [R = Ph (a), 4-F–C₆H₄ (b) or CH₂CH₂CN (c)]. The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, FAB, ¹H, ¹³C and ³¹P). The single-crystal structures of compounds 4, 4a and 5a have been established.     

Phosphorus–nitrogen compounds: Part 19. Syntheses,structural and electrochemical investigations,biological activities,and DNA interactions of new spirocyclic monoferrocenylcyclotriphosphazenes

The reactions of hexachlorocyclotriphosphazatriene, N₃P₃Cl₆, with N-alkyl-N-ferrocenylmethylethylene diamines, FcCH₂NH(CH₂)₂NHR₁ [R₁ = Me (1) and Et (2)], and sodium [3-(N-ferrocenylmethylamino)-1-propanoxide] (3) produce spirocyclic monoferrocenyl tetrachlorophosphazenes (1a–3a). The tetrapyrrolidinophosphazenes (1b–3b) are prepared from the reactions of corresponding phosphazenes (1a–3a) with excess pyrrolidine. The reaction of 1a with excess morpholine affords geminal-morpholino phosphazene (1c), whilst the reactions of 2a and 3a give diethylaminotrimorpholino (2c) and fully substituted morpholino products (3c), respectively. The structural investigations of the compounds are examined by Fourier transform IR, MS, ¹H, ¹³C, ³¹P NMR, DEPT, HETCOR, and HMBC techniques. The crystal structures of 3b and 3c are determined using X-ray crystallography. Cyclic voltammetric and chronoamperometric data show that compounds 1a–3a, 1b–3b, and 1c–3c exhibit electrochemically reversible one-electron oxidation of Fc redox centers which are hardly affected by the substituents on the phosphazene ring. The compounds 1b, 2b, 3b, and 3c are screened for antibacterial activities against Gram-positive and Gram-negative bacteria and for antifungal activities against yeast strains. In addition, the antituberculosis activities (in vitro) of these compounds are evaluated against INH-susceptible reference strain M. tuberculosis H37Rv, and six multi-drug resistant clinical M. tuberculosis isolates. Compound 2b is found to be the most active against the susceptible the reference strain. In addition, 1b, 2b, and 3c are active against all the multidrug-resistant clinical isolates at the highest concentrations. Gel electrophoresis data indicate that the compounds promote the formation of strand breaks in plasmid DNA. Almost all the concentrations lost of supercoiled DNA suggests that the compound 3b is very efficient plasmid-modifier. The compounds inhibit BamHI cleavage of pUC18 DNA while restricting HindIII.     

Structural properties of new spiro-1,3-propanediaminocyclotriphosphazene derivatives

New 1,3-propanediaminocyclotriphosphazene derivatives (7-17) were synthesized from the reactions of spiro-1,3-propanediaminocyclotriphosphazene, N₃P₃Cl₄[NH(CH₂)₃NH] (1) with the cyclopropanemethylamine (2), cyclohexylamine (3), pyrrolidine (4) cyclohexanol (5), cyclopropylmethanol (6). The structures of the novel compounds (7-17) were characterized by elemental analysis, mass spectrometry, ¹H and ³¹P NMR spectroscopy. The molecular structures of 8, 12 and 13 were determined by X-ray crystallography. The structures of all these three compounds are in the monoclinic crystal system; compounds 8 and 12 have the P21/c space group while compound 13 has the P21/n space group. The ring conformation of the cyclotriphosphazene and other external rings were investigated based on the X-ray crystal structures.     

Effect of chain length on the formation of intramolecular and intermolecular products: Reaction of diols with cyclotriphosphazene

The reactions of cyclotriphosphazene, N₃P₃Cl₆ (1), in a 1:1.2 stoichiometry with the sodium derivative of seven diols [ethane- (2a), 1,3-propane- (2b), 1,4-butane- (2c), 1,5-pentane- (2d), 1,6-hexane- (2e), 1,8-octane- (2f) and 1,10-decane- (2g) diol] in THF solution at room temperature have been used to investigate the effect of chain length on the formation of reaction products. Although no new products were found for the reaction of 1 with diols 2a-c compared to those in the literature using other bases and solution conditions, the reactions of 1 with the diols 2d-g gave six different types of products, whose structures have been characterized by elemental analysis, mass spectrometry, ¹H and ³¹P NMR spectroscopy; ansa compounds N₃P₃Cl₄[O(CH₂)_nO], (5d-5g); single-bridged compounds N₃P₃Cl₅[O(CH₂)_nO]N₃P₃Cl₅(6d-6f); double-bridged compounds N₃P₃Cl₄[O(CH₂)_nO]₂N₃P₃Cl₄ (7d-7g, syn and anti) and triple-bridged compounds, N₃P₃Cl₃[O(CH₂)_nO]₃N₃P₃Cl₃ (8d-f). Where suitable single crystals were obtained, X-ray crystallographic studies confirmed the structures of two ansa compounds (5d and 5f), one single-bridged compound (6e), and five double-bridged compounds (meso-anti for 7d, 7e, 7f and meso-syn for 7d and 7f). ³¹P NMR measurements of the reaction mixtures were used to quantify the formation of products for the reactions 1 with all the diols, 2a-g; it is found that, with increasing chain length of the diol, there is a decrease in the products formed by intramolecular reactions (spiro and ansa derivatives) and a concomitant increase in the amounts of products formed by intermolecular reactions (single-, double- and triple-bridged derivatives) of cyclophosphazene.     

Fluorescent sensor of fluorene derivatives having phosphonic acid as a fluorogenic ionophore: synthesis and static quenched properties for Fe(III)

A series of novel fluorene derivatives containing –PO(OH)₂ (1, 2), –HS (3), and –N⁺ (CH₃)₃ (4) were synthesized and only phosphonic-functionalized fluorene derivatives can detect Fe³⁺ with high selectivity over other metal ions. The fluorescence quenching of 1 and 2 with titration Fe³⁺ in water–DMF solution fits the Perrin model of static quenching. Spectral analysis showed that Fe³⁺ bound with fluorene-based chemosensor through the O-atoms at the phosphonic group to form nonfluorescent complexes. The binding ratio was estimated by the Job plot and the trace levels of iron in samples were successfully monitored.     

Synthesis and characterization of water-soluble palladium(II)-functionalized diphosphine complexes

Water-soluble functionalized bis(phosphine) ligands L (a–h) of the general formula CH₂(CH₂PR₂)₂, where for a: R = (CH₂)₆OH; b–g: R = (CH₂)_nP(O)(OEt)₂, n = 2–6 and n = 8; h: R = (CH₂)₃NH₂ ( Scheme 1), have been prepared photochemically by hydrophosphination of the corresponding 1-alkenes with H₂P(CH₂)₃PH₂. Water-soluble palladium complexes cis-[Pd(L)(OAc)₂] (1–8) were obtained by the reaction of Pd(OAc)₂ with the ligands a–h in a 1:1 mixture of dichloromethane:acetonitrile. The water-soluble phosphine ligands and their palladium complexes were characterized by IR, ¹H and ³¹P NMR. A crystallographic study of complex 1 shows that the Pd(II) ion has a square planar coordination sphere in which the acetate ligands and the diphosphine ligand deviate by less than 0.12 Å from ideal planar.     

Reactivity studies of (η-arene)ruthenium dimeric complexes towards pyrazoles: isolation of amidines, bis pyrazoles and chloro bridged pyrazole complexes

The complex [(η⁶-p-cymene)Ru(μ-Cl)Cl]₂1 reacts with pyrazole ligands (3a-g) in acetonitrile to afford the amidine derivatives of the type [(η⁶-p-cymene)Ru(L)(3,5-HRR′pz)](BF4)₂ (4a-f), where L = {HNC(Me)3,5-RR′pz}; R, R′ = H (4a); H, CH₃ (4b); C₆H₅ (4c); CH₃, C₆H₅ (4d) OCH₃ (4e); and OC₂H₅ (4f), respectively. The ligand L is generated in situ through the condensation of 3,5-HRR′pz with acetonitrile under the influence of [(η⁶-p-cymene)RuCl₂]₂. The complex [(η⁶-C₆Me₆)Ru(μ-Cl)Cl]₂2 reacts with pyrazole ligands in acetonitrile to yield bis-pyrazole derivatives such as [(η⁶-C₆Me₆)Ru (3,5-HRR′pz)₂Cl](BF₄) (5a-b), where R, R′ = H (5a); H, CH₃ (5b), as well as dimeric complexes of pyrazole substituted chloro bridged derivatives [{(η⁶-C₆Me₆)Ru(μ-Cl) (3,5-HRR′pz)}₂](BF₄)₂ (5c-g), where R, R′ = CH₃ (5c); C₆H₅ (5d); CH₃, C₆H₅ (5e); OCH₃ (5f); and OC₂H₅ (5g), respectively. These complexes were characterized by FT-IR and FT-NMR spectroscopy as well as analytical data. The molecular structures¹ of representative complexes [(η⁶-C₆Me₆)Ru{3(5)-Hmpz}₂Cl]⁺5b, [(η⁶-C₆Me₆)Ru(μ-Cl)(3,5-Hdmpz)]₂²⁺5c and [(η⁶-C₆Me₆)Ru(μ-Cl){3(5)Me,5(3)Ph-Hpz}]₂²⁺5e were established by single crystal X-ray diffraction studies.     

Dopamine derivatives from the insect Polyrhachis dives as inhibitors of ROCK1/2 and stimulators of neural stem cell proliferation

Polyrhachis dives is consumed as an insect food in some regions of China. In this study, new dopamine derivatives, (+)-polyrhadopamine A (1a) and (−)-polyrhadopamine A (1b), (+)-polyrhadopamine B (2a) and (−)-polyrhadopamine B (2b), and polyrhadopamines C–E (3–5), were isolated from this species. The structures and stereochemistry of these substances were assigned by using spectroscopic and computational methods. Compounds 1a, 1b, 2a, and 2b are dimeric N-acetyldopamine derivatives, 3 is a dopamine analog containing an unusual sulfone group, and 4 and 5 possess a rare benzo[d]thiazole moiety. The functions of these substances as ROCK1/2 inhibitors, neural stem cell (NSCs) proliferation stimulators, immunosuppressive, and anti-inflammatory agents were determined.     

Synthesis,structure and reactivity of novel palladiumdichloride-2,2′-bipyridine with 4,4′-bis(fluorous-ponytail)

With the readily available fluorous alkanols R_fCH₂OH, a series of novel fluorous-ponytailed bpy ligands, 4,4′-bis(R_fCH₂OCH₂)-2,2′-bpy (1a–e), were prepared and treated with [PdCl₂(CH₃CN)₂] to result in the corresponding novel Pd complexes [PdCl₂(4,4′-bis(R_fCH₂OCH₂)-2,2′-bpy)] (2a–e) where R_f = n-C₃F₇ (a), HCF₂(CF₂)₃ (b), HCF₂(CF₂)₇ (c), n-C₈F₁₇ (d), n-C₁₀F₂₁ (e). The new ligands and Pd complexes were spectroscopically characterized by multi-nuclei NMR (¹H, ¹⁹F and ¹³C), FTIR and high resolution mass (FAB). The structure for the Pd complex 2b, the first with fluorinated ponytails on bpy and not on phosphine, was also established by a single crystal X-ray diffraction study. The TGA data of both ligands and Pd complexes indicated that the Pd-complexes were resistant to higher temperatures than the corresponding ligands. The Pd catalysts derived from 2a–c showed an almost quantitative conversion and could be reused for eight runs with Heck reactions, in that the products and unspent reactants were directly removed by distillation. With the highest fluorine content in the series, Pd complex 2e was successfully applied in the Heck reaction using the fluorous biphasic catalysis strategy.     

Studies on the Suzuki reaction on methyl 1-(2-bromoaryl)-5-oxo-3-aryl/heteroaryl-pyrrolidin-2-carboxylate derivatives: synthesis of N-aryl modified monocyclic γ-lactam derivatives in search for newer antibacterial agents

A large number of novel N-aryl modified monocyclic γ-lactam derivatives have been prepared via Pd(0) catalyzed heteroarylation in the N-aryl part of (±) cis and (±) trans γ-lactam carboxylate derivatives 3(a–f) and 6(a–f), respectively, with furan-2-boronic acid and thiophen-2-boronic acid. (±) cis Methyl 1-(2-bromoaryl)-5-oxo-3-aryl/heteroarylpyrrolidin-2-carboxylate derivatives 3(a–f), were prepared in good yields from 1(a–f) via hydrolysis, stereoselective decarboxylation, followed by esterification. Corresponding trans isomers 6(a–f) were prepared by the standard method already reported by us.     

Greener fluorous chemistry: Convenient preparation of new types of ‘CF3-rich’ secondary alkyl mesylates and their use for the synthesis of azides, amines, imidazoles and imidazolium salts

2,2,2-Trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, and nonafluoro-tert-butyl alcohol were used as precursors for the preparation of the appropriate bis(polyfluoroalkoxymethyl)carbinols [(R_FHOCH₂)₂CHOH, 1a-c, R_FH = (a) CF₃CH₂, (b) (CF₃)₂CH, and (c) (CF₃)₃C] and the corresponding mesylates [(R_FHOCH₂)₂CHOSO₂CH₃, 2a-c]. This novel design paradigm is introduced to eliminate the persistence and bioaccumulation problems of fluorous chemistry, which are associated with the use of longer linear perfluoroalkyl groups (e.g. R_fn ≥ n-C₈F₁₇, n-C₇F₁₅). Secondary mesylates 2a,b and the primary tosylate [(CF₃)₃COCH₂CH₂OTs, 2d] displayed acceptable reactivity towards azide and imidazole nucleophiles to allow the syntheses of novel fluorous azides, which on hydrogenolysis with H₂/Pd-C offered fluorous amines [(R_FHOCH₂)₂CHNH₂, 8a,b], and 1-(polyfluoroalkyl)imidazoles (5a,b,d), respectively, while 2c showed no reactivity due to steric hindrance. The reaction of 8a,b with formaline, glyoxal and hydrochloric acid gave symmetrical 1,3-dialkylated imidazolium chlorides (9a,b), while 5a,b,d were effectively alkylated using n-C₈F₁₇(CH₂)₃I, methyl iodide, 2-bromoethanol, and 2d to yield the corresponding 1,3-dialkylimidazolium iodides, bromides, and tosylates (7aa-ec). Some physical properties of new compounds including mp, bp and solubility patterns were also analyzed; and the fluorophilicity values of 1a-c, and 2a-c were experimentally determined by GC and/or ¹⁹F NMR spectroscopy.     

Carbonyl complexes of manganese, rhenium and molybdenum with 2-pyridylimino acid ligands

[MBr(CO)₃{κ²(N,O)-pyca}] [M = Mn(1a), Re(1b), pyca = pyridine-2-carboxaldehyde] and [MoCl(η³-C₃H₄Me-2)(CO)₂{κ²(N,O)-pyca}] (1c) react with aminoacid β-alanine to give the corresponding iminopyridine complexes 2a-2c. The same method affords the iminopyridine derivatives from γ-aminobutyric acid (GABA) (3a-3c) and 3-aminobenzoic acid (4a-4c). For complexes 2a-2c, 3a, 3c and 4a, the solid state structures have been determined by X-ray crystallography, revealing interesting differences in their hydrogen-bonding patterns in solid state.     

Synthesis, coordination studies and redox properties of a novel ditertiary phosphine bearing two ferrocenyl groups

The new ferrocenyl substituted ditertiary phosphine {FcCH₂N(CH₂PPh₂)CH₂}₂ [Fc = (η⁵-C₅H₄)Fe(η⁵-C₅H₅)] (1) was prepared, in 72% yield, by Mannich based condensation of the known bis secondary amine {FcCH₂N(H)CH₂}₂ with 2 equiv. of Ph₂PCH₂OH in CH₃OH. Phosphine 1 readily coordinates to various transition-metal centres including Mo⁰, Ru^II, Rh^I, Pd^II, Pt^II and Au^I to afford the heterometallic complexes {RuCl₂(p-cym)}₂(1) (2), (AuCl)₂(1) (3), cis-PtCl₂(1) (4), cis-PdCl₂(1) (5), cis-Mo(CO)₄(1) (6), trans,trans-{Pd(CH₃)Cl(1)}₂ (7) and trans,trans-{Rh(CO)Cl(1)}₂ (8). In complexes 2, 3, 7 and 8 ligand 1 displays a P,P′-bridging mode whilst for 4-6 a P,P′-chelating mode is observed. All new compounds have been fully characterised by spectroscopic and analytical methods. Furthermore the structures of 1, 2 · 2CH₂Cl₂, 3 · CH₂Cl₂, 4 · CH₂Cl₂, 6 · 0.5CHCl₃ and 8 have been elucidated by single crystal X-ray crystallography. Electrochemical measurements have been undertaken, and their redox chemistry discussed, on both noncomplexed ligand 1 and representative compounds containing this new ditertiary phosphine.     

Reactivity of 1-boraadamantanes towards bis(trialkylstannyl)ethynes. First examples of 3-boratricyclo[5.3.1.1]dodecanes, and the molecular structure of a tetraalkyldiboroxane

1-Boraadamantane (1) and 2-ethyl-1-boraadamantane (1(2-Et)) react with bis(trialkylstannyl)ethynes (3), R₃Sn-CC-SnR₃ with R=Me (a), Et (b), in a 1:1 molar ratio by 1,1-organoboration under very mild conditions to give the 4-methylene-3-borahomoadamantane derivatives 4a,b and 7a,b, respectively, which are dynamic at room temperature with respect to deorganoboration. The compounds 4a,b react further with 3a,b by 1,1-organoboration to the tricyclic butadiene derivatives 5a,b. Attempts to crystallise 4a afforded the product of hydrolysis, the diboroxane 6a which was characterised by X-ray structural analysis. All products were characterised in solution by ¹H-, ¹¹B-, ¹³C- and ¹¹⁹Sn-NMR spectroscopy.     

Ferrocenoyl peptides with sulfur-containing side chains: synthesis, solid state and solution structures

The synthesis and full characterization of a number of amino acid and dipeptide derivatives with sulfur-containing side chains derived from ferrocene carboxylic acid and ferrocene-1,1′-dicarboxylic acid is presented. In particular, compounds Fc-CO-(Aaa)_n-OMe (4) and Fe[C₅H₄-CO-(Aaa)_n-OMe]₂ (3) with (Aaa)_n = Cys(Bzl) (a), Cys(Bzl)-Cys(Bzl) (b), Cys(p-OMe-Bzl) (c), Cys(p-OMe-Bzl)-Cys(p-OMe-Bzl) (d), Met (e), and Met-Met (f) were prepared. Also, the free acid derivatives Fe[C₅H₄-CO-Met-OH]₂ (6e) and Fc-CO-Met-OH (7e) were prepared and characterized. The solid state structures of 3a, 4b, and 4e were determined by single crystal X-ray diffraction. Compound 3a shows a 1,3′ substitution pattern on the Cp rings in the solid state. Structures in solution were determined by NMR, IR and CD spectroscopy, with particular emphasis on the question of hydrogen bonding and helical chirality of the metallocene. As an example, the full assignment for the Cp signals in the disubstituted derivative 3a was achieved by simulation of the ¹H NMR signals from the cyclopentadienyl ring in combination with 2D-NOESY spectra. In solution, 3a has the known 1,2′ substitution pattern, which is stabilized by intramolecular hydrogen bonds.     

CMPO-substituted calix[6]- and calix[8]arene extractants for the separation of An/Ln from radioactive waste

Three calix[6]arene derivatives (1a-c) and two calix[8]arene derivatives (2a,b), with six and eight CMPO residues, respectively, attached to the narrow/lower rim via ether links, were synthesised. Preliminary liquid-liquid extraction studies for Eu(III) and Am(III) from aqueous nitric acid to o-nitrophenylhexyl ether reveal remarkable properties with respect to efficiency and selectivity, especially for the tert-butylcalix[6]arene derivative with a -(CH₂)₃- spacer.     

Microwave-assisted and conventional synthesis and stereogenic properties of monospirocyclotriphosphazene derivatives

The reactions of hexachlorocyclotriphosphazene, N₃P₃Cl₆, with N/O donor type N-alkyl or (aryl)-o-hydroxybenzylamines HO(C₆H₄)CH₂NHR(Ar), [R(Ar) = C(CH₃)₃ (1), Ph (2)] produce monospirocyclic tetrachlorocyclotriphosphazenes (1a and 2a). The geminal substituted cyclotriphosphazenes (1b, 1d, 2b and 2d) are obtained from the reactions of 1 equiv. of 1a and 2a with 2 equiv. of pyrrolidine or morpholine in THF, while the fully substituted phosphazenes (1c, 1e, 2c and 2e) are formed from the reactions of 1a and 2a with the excess pyrrolidine or morpholine in toluene, between 24 and 48 h. The microwave-assisted reactions of 1a and 2a with excess pyrrolidine or morpholine in toluene afford the fully substituted products with higher yields than those which were obtained by conventional methods. The structural investigations of the compounds have been verified by elemental analyses, ESI-MS, FTIR, ¹H, ¹³C, ³¹P NMR and HETCOR techniques. The crystal structure of 2a is determined by X-ray crystallography and the phosphazene ring is in the flattened boat form. Compounds 1b, 1d, 2b and 2d in which the spiro aryloxy moiety provides the one centre of chirality exist as racemates and the chirality has been confirmed by ³¹P NMR spectroscopy on addition of a chiral solvating agent (CSA), (S)-(+)-2,2,2-trifluoro-1-(9′-anthryl)ethanol.     

Synthesis,structure and spectroelectrochemical property of (2,2′-bipyridine)–metal (M = Pt,Pd) dichloride with 4,4′-bis(fluorous-ponytail) on bipyridine

The 4,4′-bis(R_fCH₂OCH₂)-2,2′-bpy ligands [R_f = n-C₃F₇ (1a), HCF₂(CF₂)₃ (1b)] were prepared and then treated with [MCl₂(CH₃CN)₂] (M = Pt or Pd) to result in the corresponding metal complexes, [MCl₂(4,4′-bis(R_fCH₂OCH₂)-2,2′-bpy)] (M = Pt 2a–b; Pd 3a–b). Both ligands and metal complexes were fully characterized by multi-nuclei NMR (¹H, ¹⁹F and ¹³C), FTIR, and mass (GC/MS or HR-FAB) methods. The X-ray structures of 2a–b and 3a–b were studied. With terminal CF₃, the structures of 2a and 3a exhibit disordered polyfluorinated regions in solid state. With terminal HCF₂, the structures of 2b and 3b show a π–π stacking of the bpy planes, five-membered C–H···O hydrogen bond and an unusual intramolecular blue-shifting C–H···F–C hydrogen bond system, whereas without terminal HCF₂, the structures of 2a and 3a show the similar π–π stacking, five-membered C–H···O hydrogen bond and typical orientation of polyfluorinated ponytails, but not the C–H···F–C hydrogen bond system. The CV and UV/Vis studies were also carried out.