Complexes In CH2Cl2 Research Articles

Synthesis and characterization of pyrrole-based group 4 PNP pincer complexes

The synthesis, characterization, and reactivity of several group 4 metal complexes featuring a central anionic pyrrole moiety connected via CH2 linkers to two phosphine donors is described. Treatment of [P(NH)P-iPr] with [MCl4(THF)2] (M = Zr, Hf) in the presence of base yields the dimeric complexes [M(PNPiPr)(μ-Cl)(Cl)2]2 featuring two bridging chloride ligands. These complexes react with sodium cyclopentadienyl and SiMe3I to give the mononuclear complexes [M(PNPiPr)(η5-Cp)(Cl)2] and [M(PNPiPr)(I)3], respectively. The latter react with MeMgBr to form the trialkyl complexes [M(PNPiPr)(Me)3]. Upon treatment of [Ti(NMe2)4] with [P(NH)P-iPr] a complex with the general formula [Ti(PNPiPr)(NMe2)3] is obtained. DFT calculations revealed that the most stable species is [Ti(κ1N- PNPiPr)(NMe2)3] featuring a κ1N-bound PNP ligand. When [P(NH)P-iPr] is reacted with [Ti(NMe2)4] in CH2Cl2 complex [Ti(PNPiPr)(Cl)2(NMe2)] is formed. Treatment of a solution of [P(NH)P-iPr] and [Zr(NMe2)4] with SiMe3Br affords the anionic seven-coordinate tetrabromo complex [Zr(PNPiPr)(Br)4][H2NMe2]. The corresponding hafnium complex [Hf(PNPiPr)(Br)4][H2NEt2] is obtained in similar fashion by utilizing [Hf(NEt2)4] as metal precursor. All complexes are characterized by means of NMR spectroscopy. Representative complexes were also characterized by X-ray crystallography.Graphical abstract

A Methoxylation-Promoted CPET Reaction.

The manuscript discloses a methoxylation reaction to an aromatic carbonyl function that carries out a CPET reaction oxidizing a transition metal ion. Spontaneous methoxylation of a redox non-innocent fragment coordinated to a high spin cobalt(II) ion, promoted concerted proton electron transfer (CPET) reaction oxidizing cobalt(II) to cobalt(III) in air and subsequent demethoxylation induced reduction of cobalt(III) to cobalt(II) producing H2 O2 are authenticated. The cobalt(III)/cobalt(II) electron transfer (ET) potential of the designed complex in CH2 Cl2 is -0.27 V vs Fc+ /Fc redox couple. However, in presence of MeOH the reduction potential decreases to -1.02 V due to CPET involving MeOH proton. In CH2 Cl2 /CHCl3 spontaneous demethoxylation occurs giving back the original complex and reactive methoxyl radical that reacts with O2 producing H2 O2 . Overall one molecule of MeOH produces one molecule of H2 O2 . To analyze the involvement of the proton, the rate constants of the CPET reactions in CH2 Cl2 -MeOH (2 : 1) and CH2 Cl2 -CD3 OD (2 : 1) and the demethoxylation reaction in CHCl3 at 330 K were determined by time drive UV-Vis spectroscopy.

Cytotoxicity and Apoptosis-Induction in MCF-7 Cells for New Pd(II) Complex Based on s-Triazine Ligand: Synthesis, Single Crystal X-ray Diffraction Analysis and Structural Investigations

The synthesis and X-ray structure analysis of the new [PdLCl2]*0.5 CH2Cl2 complex where L is hydrazono-s-triazine di-morpholine derivative, were presented. In the neutral inner sphere of this complex, the organic ligand L is acting as a NN-bidentate chelate via the pyridine and hydrazone N-atoms. The coordination configuration of the Pd(II) is completed by two chloride ions at cis-positions. The tetra-coordinated Pd(II) showed a distorted square planar geometry. The outer sphere comprised half methylene chloride molecule per [PdLCl2] as crystal solvent. The crystal stability is dominated by a number of weak C-H…N, C-H…Cl, and C-H…O non-covalent interactions. Based on Hirshfeld analysis, the H…H, N…H, H…Cl, O…H, Pd…C, and Cl…C intermolecular interactions contributed by 45.2, 9.3, 21.5, 5.8, 2.3, and 3.4%, respectively. DFT studies revealed closed shell characters for the Pd-N and Pd-Cl coordinate bonds. The net charge of Pd is also predicted to be 0.311 e and the amount of electron density transferred from the ligand groups is 1.689 e. The Pd(II) complex exhibited potent cytotoxic activity against MCF-7, HepG2, and A549 cells with IC50 values of 1.18, 4.74, and 5.22 μg/mL, compared to cisplatin with IC50 values of 4.1, 9.7, and 12.3 μg/mL, respectively. Additionally, it exhibited poor cytotoxicity against WISH cells with much higher IC50 values (IC50 = 37.2 μg/mL). Investigating apoptosis-induction, the Pd(II) complex induced apoptotic cell death by an 11-fold change in MCF-7 cells arresting the cell phase at the G0–G1 phase. Accordingly, Pd(II) complex can be developed as a promising anti-breast cancer agent.

Benzo[g]quinoxaline-Based Complexes [Ir(pbt)2(dppn)]Cl and [Ir(pt)2(dppn)]Cl: Modulation of Photo-Oxidation Activity and Light-Controlled Luminescence

Based on benzo[i]dipyrido[3,2-a:2',3'-c]phenazine (dppn) with photo-oxidation activity, complexes [Ir(pbt)2(dppn)]Cl (1) and [Ir(pt)2(dppn)]Cl (2) have been synthesized (pbtH = 2-phenylbenzothiazole, and ptH = 2-phenylthiazole), with two aims, including studying the influence of the cyclometalating ligands (pbt- in 1, pt- in 2) on the photo-oxidation activity of these complexes and exploring their photo-oxidation-induced luminescence. Both 1H nuclear magnetic resonance (NMR) and electrospray (ES) mass spectrometry indicate that the benzo[g]quinoxaline moiety in complex 1 can be oxidized at room temperature upon irradiation with 415 nm light. Thus, this complex in CH2Cl2 shows photo-oxidation-induced turn-on yellow luminescence. In contrast, complex 2 reveals significant structural decomposition during the process of photo-oxidation due to incorporating a cyclometalating ligand pt- instead of pbt- in complex 1. In this paper, we report the photo-oxidation behaviors and the related luminescence modulation in 1 and 2 and discuss the relationship between structure and photo-oxidation activity in these complexes.

Synthesis, Photophysical and Electrochemical Studies of Β-Disubstituted Silver Corroles

β-Substituted corroles have been widely used in variety of applications and exhibit unique electronic and photophysical properties [1]. π-Extension at the β-position using functional groups such as phenylethynyl or pyrrolopyrazino induces intriguing stability and planarity of the macrocyclic core [2]. Keeping this in mind, a series of β-disubstituted silver tritolylcorroles (R2[TTC]Ag) have been synthesized via Pd-catalyzed reactions in good to excellent yields (Fig. 1a). Herein we are trying to investigate the effect of the various β-substituents such as methyl (Me), phenyl (Ph), methyl acrylate (MA) and phenylethynyl (PE) on photophysical and electrochemical properties. In cyclic voltammetric studies, the first oxidation potential of Me2[TTC]Ag 2 decreases (cathodic shift) by 70 mV compared to [TTC]Ag due the inductive effect of two methyl groups while in case of (MA)2[TTC]Ag 4, there is large anodic shift (170 mV) in the first oxidation potential probably due to strong electron withdrawing effect of two methyl acrylate group compared to 2 (Fig. 1b). Complex 4 depicted very high dipole moment (10.31 D), which could be utilized in NLO studies (Fig. 1c). We have investigated the effect of both electron-accepting and -donating substituents through single, double and triple bond on the macrocyclic ring using photophysical, theoretical and electrochemical studies. Complexes (2-5) exhibited remarkable broadening and increase in the intensity of red shifts of soret and Q bands of absorption spectra. Here, we have synthesized corroles with side extension of π-arm which helps in shifting of Q bands towards NIR region which could be helpful in PDT or optoelectronic applications. Figure 1. (a) Molecular structures of R2[TTC]Ag; (b) Comparative Cyclic voltammograms (CVs) of [TPC]Ag, Me2[TTC]Ag and MA2[TTC]Ag complexes in CH2Cl2 at 298 K under argon atmosphere; (c) The directions of calculated dipole moment of MA2[TTC]Ag. References (a) R. Mishra, B. Basumatary, R. Singhal, G. D. Sharma and J. Sankar, ACS Appl. Mater. Interfaces 2018, 10, 31462–31471; (b) S. Gonglach, S. Paul, M. Haas, F. Pillwein, S. S. Sreejith, S. Barman, R. De, S. Müllegger, P. Gerschel, U. P. Apfel, H. Coskun, A. Aljabour, P. Stadler, W. Schöfberger and S. Roy, Commun. 2019, 10, 1–10; (c) W. Sinha, A. Mahammed, N. Fridman, Z. Gross, ACS Catal., 2020, 10, 3764–3772; (d) R. F. Einrem, A. B. Alemayehu, S. M. Borisov, A. Ghosh, O. A. Gederaas, ACS Omega 2020, 5, 10596–10601.(a) P. Yadav, M. Sankar, X. Ke, L. Cong, K. M. Kadish, Dalton Trans. 2017, 46, 10014–10022; (b) M. Stefanelli, M. L. Naitana, M. Chiarini, S. Nardis, A. Ricci, F. R. Fronczek, C. Lo Sterzo, K. M. Smith, R. Paolesse, J. Org. Chem. 2015, 2015, 6811–6816; (c) B. Berionni Berna, S. Nardis, P. Galloni, A. Savoldelli, M. Stefanelli, F. R. Fronczek, K. M. Smith, R. Paolesse, Org. Lett. 2016, 18, 3318–3321. Figure 1

Synthesis, Structure, Reactivity and Catalytic Implications of a Cationic, Acetylide-Bridged Trigold-JohnPhos Species.

The cationic complex [(JohnPhos-Au)3 (acetylide)][SbF6 ] (JohnPhos=(2-biphenyl)di-tert-butylphosphine, L1) has been characterised structurally and features an acetylide-trigold(I)-JohnPhos system; the trinuclear-acetylide unit, coordinated to the monodentate bulk phosphines, adopts an unprecedented μ,η1 ,η2 ,η1 coordination mode with an additional interaction between distal phenyl rings and gold centres. Other cationic σ,π-[(gold(I)L1)2 ] complexes have also been isolated. The reaction of trimethylsilylacetylene with various alcohols (iPrOH, nBuOH, n-HexOH) catalysed by cationic [AuI L1][SbF6 ] complexes in CH2 Cl2 at 50 °C led to the formation of acetaldehyde acetals with a high degree of chemo- and regioselectivity. The reaction mechanism was studied, and several organic and inorganic intermediates have been characterised. A comparative study with the analogous cationic [CuI L1][PF6 ] complex revealed different behaviour; the copper metal is lost from the coordination sphere leading to the formation of cationic vinylphosphonium and copper nanoparticles. Additionally, a new catalytic approach for the formation of this high-value cationic vinylphosphonium has been established.

Synthesis, Spectral and Electrochemical Redox Properties of EAA-Appended Porphyrins

Porphyrins having nitro substituents at β-position can act as excellent synthons for further functionalization of porphyrins having wide range of applications [1]. β-Nitro-meso-tetraarylporphyrins can be further functionalized in presence of Michael donor such as active methylene compounds which result in the formation of porphyrins and chlorins depending on reaction conditions and bulkiness of the Michael donor [2-5]. A wide variety of active methylene compounds such as 1,3-dicarbonyls, diketoesters and malonates can undergo Michael addition reactions under mild basic conditions [6]. In this regard, we report the selective synthesis of 2-EAA-5,10,15,20-tetraphenylporphyrins and their metal complexes (Fig. 1a) [7]. All of the synthesized EAA-appended porphyrins exhibited enol tautomeric form in solution predominantly. However, there is no keto-enol tautomerism in it as there is no peak for -CH in 1H NMR spectrum. EAA-appended porphyrins have shown multiple oxidations and reductions in cyclic voltammograms possibly due presence of EAA group on porphyrin ring (Fig. 1b).MTPP(EAA) where M = 2H, Co(II), Ni(II), Cu(II) and Zn(II) exhibited a remarkable red shift (10-15 nm) in the B and Q bands as compared to the corresponding MTPPs, whereas all these porphyrins have bands which are blue-shifted by ∼10-14 nm as compared to their precursor, i.e., MTPP(NO2). In this presentation, we will present the synthesis, spectral and electrochemical redox properties of EAA-appended porphyrins. Figure 1. (a) Molecular structures of synthesized porphyrins and (b) Cyclic voltammograms (CVs) of CuTPP, CuTPP(NO2) and CuEAA complexes in CH2Cl2 at 298 K.

Control of Excited-State Supramolecular Assembly Leading to Halide Photorelease.

Ground- and excited-state control of halide supramolecular assembly was achieved through the preparation of a series of ester- and amide-functionalized ruthenium polypyridyl complexes in CH2Cl2. Hydrogen-bonding amide and alcohol groups on the receptor ligand were found to direct interactions with halide, while halide association with the ethyl ester groups was not observed. The various functional groups on the receptor ligands tuned the ground-state equilibrium constants over 2 orders of magnitude (1 × 105 to 1 × 107 M-1), and the fractional contribution of each hydrogen-bond donor to the total equilibrium constant was determined. Pulsed-laser excitation of the complexes resulted in excited-state localization on the ester- or amide-functionalized ligands. In the case where the excited state was oriented toward an associated halide ion (the amide complexes), an 80 ± 10 meV Coulombic repulsion was induced that lowered the excited-state equilibrium constant ( K*eq) and resulted in halide photorelease. The rate constants for excited-state halide release ( k*21) were determined, and the values varied based on the functional groups present in the receptor ligand. Complexes with more hydrogen-bonding donors had smaller rate constants for halide photorelease. In a complex without a specific receptor ligand, the excited-state dipole was not oriented toward the associated halide, and the excited state was therefore found to have a larger equilibrium constant for halide association than the ground state.

Highly luminescent film as enhancer of photovoltaic devices

The most extended Si based conventional photovoltaic cells show low efficiency in the UV region, however this low efficiency can be enhanced by the use of suitable down-shifters or down-converters which transform the wavelength of the incoming radiation into a wavelength for which the Si based cells have high efficiency. In this sense europium(III) luminescent benzoate and phenanthroline (and derivatives) complexes are good candidates for such purposes since they exhibit large absorption at wavelengths below 400 nm and significant emissions at the VIS range. In this work we report the synthesis the crystal structure and the spectroscopic properties of two new Eu3+ and Gd3+ complexes with the ligands 4,7-biphenyl-1,10-phenanthroline (bphen) and benzoate (bz), namely, [Eu2(bphen)2(bz)6] (1) and [Gd2(bphen)2(bz)6] (2). The X-ray single crystal study reveals a dinuclear molecular structure for the Eu3+ complex with two bridging benzoate ligands between the two equivalent Eu3+ ions. The Powder X-ray diffraction study shows that the Eu3+ and Gd3+ compounds are isostructural and allows the use of the Gd3+ compound for the characterization of the excited states of the complexes which were investigated to explain the sensitization process that lead to intense red emission of Eu3+ ions under UV excitation. The photoluminescence study of the lanthanide complexes at 15 K and 297 K revealed very efficient energy transfer processes from the antenna to the emitting Eu3+ ions and a high overall quantum yield. Moreover, the ligands provide rigidity, high stability and solubility to the complex in CH2Cl2, allowing the preparation of poly(methylmethacrylate)-doped films that can be used to cover photovoltaic devices. The analysis of external quantum yield and quantum efficiency (EQE) show its potential application to the solar cell technology with an enhancement EQE in the UV region (280–360 nm) that reaches a 4.5% at 300 nm.

Heterobimetallic Nitrido Complexes of Group 8 Metalloporphyrins.

Heterobimetallic nitrido porphyrin complexes with the [(L)(por)M-N-M'(LOEt)Cl2] formula {por2- = 5,10,15,20-tetraphenylporphyrin (TPP2-) or 5,10,15,20-tetra(p-tolyl)porphyrin (TTP2-) dianion; LOEt- = [Co(η5-C5H5){P(O)(OEt)2}3]-; M = Fe, Ru, or Os; M' = Ru or Os; L = H2O or pyridine} have been synthesized, and their electrochemistry has been studied. Treatment of trans-[Fe(TPP)(py)2] (py = pyridine) with Ru(VI) nitride [Ru(LOEt)(N)Cl2] (1) afforded Fe/Ru μ-nitrido complex [(py)(TPP)Fe(μ-N)Ru(LOEt)Cl2] (2). Similarly, Fe/Os analogue [(py)(TPP)Fe(μ-N)Os(LOEt)Cl2] (3) was obtained from trans-[Fe(TPP)(py)2] and [Os(LOEt)(N)Cl2]. However, no reaction was found between trans-[Fe(TPP)(py)2] and [Re(LOEt)(N)Cl(PPh3)]. Treatment of trans-[M(TPP)(CO)(EtOH)] with 1 afforded μ-nitrido complexes [(H2O)(TPP)M(μ-N)Ru(LOEt)Cl2] [M = Ru (4a) or Os (5)]. TTP analogue [(H2O)(TTP)Ru(μ-N)Ru(LOEt)Cl2] (4b) was prepared similarly from trans-[Ru(TTP)(CO)(EtOH)] and 1. Reaction of [(H2O)(por)M(μ-N)M(LOEt)Cl2] with pyridine gave adducts [(py)(por)M(μ-N)Ru(LOEt)Cl2] [por = TTP, and M = Ru (6); por = TPP, and M = Os (7)]. The diamagnetism and short (por)M-N(nitride) distances in 2 [Fe-N, 1.683(3) Å] and 4b [Ru-N, 1.743(3) Å] are indicative of the MIV═N═M'IV bonding description. The cyclic voltammograms of the Fe/Ru (2) and Ru/Ru (4b) complexes in CH2Cl2 displayed oxidation couples at approximately +0.29 and +0.35 V versus Fc+/0 (Fc = ferrocene) that are tentatively ascribed to the oxidation of the {LOEtRu} and {Ru(TTP)} moieties, respectively, whereas the Fe/Os (3) and Os/Ru (5) complexes exhibited Os-centered oxidation at approximately -0.06 and +0.05 V versus Fc+/0, respectively. The crystal structures of 2 and 4b have been determined.

Synthesis and speciation of zirconium tetrafluoride complexes with phosphoryl-containing bases Ph3PO, Bu3PO and (Me2N)3PO in solutions

Zirconium fluoro complexes with phosphoryl-containing bases (L) have been synthesized by the reaction of a suspension of ZrF4(dmso)2 in toluene with an excess of Ph3PO or Bu3PO, as well as (Me2N)3PO in CH2Cl2. The composition and structure of the complexes in CH2Cl2 solutions have been studied by 19F NMR in the temperature range 293–203 K. Phosphine oxides are substituted for dmso to form mainly cis-tetrafluoro species, insignificant amounts of trans-tetrafluoro species, and mer- and fac-[ZrF3L3]+ complexes. In addition to these species, the reaction with Bu3PO yields the dimeric oxo complex (µ-O)[ZrF3(Bu3PO)2]2. Hydrolysis of fluoro complexes in CH2Cl2 with the use of an NBu4OH solution in iso-PrOH does not lead to oxo and hydroxo complexes: first, the [ZrF5L]– complex is formed, and the final hydrolysis product is ZrF6 2-. The fine structure of 19F NMR resonance lines for the zirconium fluoride compounds [ZrF5L]–, cis- [ZrF4L2], dimeric oxo complex, and mer-[ZrF3L3]+ in organic solvents has been observed for the first time, which makes it possible to reliably identify the composition and structure of the zirconium coordination polyhedron in the complexes under consideration.

A CH2Cl2 complex of a [Rh(pincer)](+) cation.

The CH2Cl2 complex [Rh((tBu)PONOP)(κ(1)-ClCH2Cl)][BAr(F)4] is reported, that also acts as a useful synthon for other complexes such as N2, CO and H2 adducts; while the analogous PNP complex undergoes C-Cl activation.

Asymmetric hydrogenation of diethyl 1-phenylvinylphosphonate by metal complexes in CH2Cl2 and in supercritical carbon dioxide using phosphite-type ligands

Asymmetric hydrogenation of diethyl 1-phenylvinylphosphonate was carried out for the first time in dichloromethane and supercritical carbon dioxide in the presence of phosphite and amidophosphite ligands. The catalysts based on [Ir(COD)2]BARF (COD is 1,5-cyclooctadiene, BARF is tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion), provide higher enantioselectivity than [Ir(COD)Cl]2 and [Rh(COD)2]BF4 do.

Reductive and oxidative electrochemical study and spectroscopic properties of nickel(II) complexes with N2O2 Schiff bases derived from (±)-trans-N,N′-bis(salicylidene)-1,2-cyclohexanediamine

Cyclic voltammetry, chronopotentiometry, chronocoulometry, controlled potential electrolysis and UV VIS were used in investigation of ligands and Ni(II) complexes with (±)-trans-N,N′-bis(salicylidene)-1,2-cyclohexanediamine substituted in orto- and/or para- positions of phenolate anions with tert-butyl and/or methoxy groups. Irreversible reduction and oxidation of ligands were shown. No influence of solvent on reduction of complexes, which results in Ni(I) complexes, was observed, however, an effect of solvent and substituents of phenolate anions on oxidation processes was proved. Anodic process in (CH3)2SO always results in appropriate Ni(III)-phenolate complex. Oxidation of orto- and para- substituted complexes in CH2Cl2 results in Ni(II)-mono-phenoxyl radicals, which undergo delocalisation and subsequently are oxidised to Ni(II)-bis-phenoxyl radicals. Last oxidation step of radicals produce long-lived Ni(II)-bis-phenoxonium cations. Complexes without substituents in para-and/or orto- position having formed Ni(II)-mono-phenoxyl radicals undergo dimerization. Mechanisms of electrode processes were studied and D and Ef values for processes of reduction and Ist step of oxidation of complexes were calculated.

Aggregation-Induced Emission Enhancement in Alkoxy-Bridged Binuclear Rhenium(I) Complexes: Application as Sensor for Explosives and Interaction with Microheterogeneous Media

The aggregation-induced emission enhancement (AIEE) characteristics of the two alkoxy-bridged binuclear Re(I) complexes [{Re(CO)3(1,4-NVP)}2(μ2-OR)2] (1, R = C4H9; 2, C10H21) bearing a long alkyl chain with 4-(1-naphthylvinyl)pyridine (1,4-NVP) ligand are illustrated. These complexes in CH2Cl2 (good solvent) are weakly luminescent, but their intensity increased enormously by almost 500 times by the addition of poor solvent (CH3CN) due to aggregation. By tracking this process via UV-vis absorption and emission spectral and TEM techniques, the enhanced emission is attributed to the formation of nanoaggregates. The nanoaggregate of complex 2 is used as a sensor for nitroaromatic compounds. Furthermore, the study of the photophysical properties of these binuclear Re(I) complexes in cationic, cetyltrimethylammonium bromide (CTAB), anionic, sodium dodecyl sulfate (SDS), and nonionic, p-tert-octylphenoxypolyoxyethanol (TritonX-100, TX-100), micelles as well as in CTAB-hexane-water and AOT-isooctane-water reverse micelles using steady-state and time-resolved spectroscopy and TEM analysis reveals that the nanoaggregates became small and compact size.

Large π‐Conjugated Chromophores Derived from Tetrathiafulvalene

AbstractA large π‐conjugated chromophore composed of two dipyrido[3,2‐a:2′,3′‐c]phenazine units directly fused to the central tetrathiafulvalene core has been prepared as a bridging ligand and its strong binding ability to Ru2+ to form a new dinuclear complex is presented. The electronic absorption and luminescence spectra and the electrochemical behavior of the free ligand and the Ru2+ complex have been investigated in detail. The free ligand shows a very strong band in the UV region consistent with ligand‐centered π–π* transitions and an intense broad band in the visible region that corresponds to an intramolecular charge‐transfer (ILCT) transition. Upon coordination, a metal‐to‐ligand charge‐transfer band appears at 22520 cm−1, and the ILCT band is bathochromically shifted by 1620 cm−1. These electrochemically amphoteric chromophores have also been characterized by spectro‐electrochemical methods. The oxidized radical species of the free ligand show a strong tendency to undergo aggregation, in which long‐distance attractive interactions overcome the electrostatic repulsion. Moreover, these two new chromophores reveal an ILCT fluorescence with large solvent‐dependent Stokes shifts and quantum efficiencies of 0.052 for the free ligand and 0.016 for its dinuclear Ru2+ complex in CH2Cl2.

Synthesis and properties of boron complexes of [14]triphyrins(2.1.1)

Boron complexes of [14]triphyrins(2.1.1) were prepared from free-base [14]triphyrins(2.1.1) with phenylboron dichloride. The absorption spectrum of the meso-free β-alkyl-triphyrin boron complex in CH2Cl2 showed a broad weak band at around 640 nm assigned to transition from B-phenyl to the triphyrin, while that of the meso-aryl benzotriphyrin boron complex showed only Soret and Q bands.

Syntheses, Dynamic Behaviour and Theoretical Studies of [(Piperidinomethyl)silyl]methyl‐Cyclopalladated Dimetallic Complexes

AbstractThe cationic complex [Pd{CH2SiPh2(CH2NC5H10)‐κ2C,N}(NCMe)2]BF4 (CH2NC5H10 = piperidinomethyl) is obtained from the reaction of [Pd{CH2SiPh2(CH2NC5H10)‐κ2C,N}(μ‐Cl)]2 with TlBF4 in the presence of NCMe. It reacts with KO2CCH3 leading to the dimetallic complex [Pd{CH2SiPh2(CH2NC5H10)‐κ2C,N}(μ‐O2CCH3‐κO:κ′O)]2, which exists only as the transoid isomer in solution. A dynamic process due to inversion of the acetato bridges is detected by variable‐temperature 1H NMR spectroscopy. The reaction of the same parent complex with Kdmpz (dmpz = dimethylpyrazolate) leads to the dinuclear complex [Pd{CH2SiPh2(CH2NC5H10)‐κ2C,N}(μ‐dmpz‐κN:κ′N)]2, which in solution exists as a mixture of cisoid and transoid isomers, but no inversion of the bridging pyrazolato groups has been observed. The reaction between equimolar amounts of these two complexes in CH2Cl2 affords low yields of the expected mixed acetato/pyrazolato‐bridged complex [Pd2{CH2SiPh2(CH2NC5H10)‐κ2C,N}2(μ‐O2CCH3‐κO:κ′O)(μ‐dmpz‐κN:κ′N)]. The mixed chlorido‐pyrazolato‐bridged complex [Pd2{CH2SiPh2(CH2NC5H10)‐κ2C,N}2(μ‐Cl)(μ‐dmpz‐κN:κ′N)] is obtained by mixing equimolar amounts of the parent dichlorido‐ and bis(dimethylpyrazolato)‐bridged dinuclear complexes, and exhibits a dynamic process in solution corresponding to the inversion of the bridges. Only the cisoid isomers are detected for both dimetallic complexes with mixed bridging ligands. The experimental findings of the preferred transoid or cisoid structure in these dinuclear Pd complexes were supported by quantum chemical calculations.

Synthesis and characterization of [Ru(η6-C10H14)(dppf)X][PF6] (X = Cl, Br, I, SnF3) compounds: The X-ray structure of [Ru(η6-C10H14)(dppf)Cl][SnCl3]·0.45CH2Cl2

The arene–ruthenium complex [Ru(η6-C10H14)(dppf)Cl]PF6 (1) was used as a precursor for the syntheses of the [Ru(η6-C10H14)(dppf)Br]PF6 (2), [Ru(η6-C10H14)(dppf)I]PF6 (3), [Ru(η6-C10H14)(dppf)SnF3]PF6 (4) and [Ru(η6-C10H14)(dppf)Cl][SnCl3]·0.45CH2Cl2 (5) complexes by its reactions with KBr, KI, SnF2 and SnCl2, respectively. All of the compounds were characterized by NMR, IR, 57Fe and 119Sn-Mössbauer spectroscopy, and cyclic voltammetry. The single-crystal X-ray structure analysis of the [Ru(η6-C10H14)(dppf)Cl][SnCl3]·0.45CH2Cl2 complex revealed the expected piano-stool geometry. Cyclic voltammograms of the complexes showed only one quasi-reversible electrochemical process, involving the oxidation of Fe(II) and Ru(II) at the same potential, which was confirmed by exhaustive electrolysis experiments. 57Fe-Mössbauer parameters obtained for the complexes (1–5) were fitted with one doublet corresponding to a site of one iron(II). The 119Sn-Mössbauer parameters of the complex (4) indicate that tin is tetra covalent.

Synthesis and photophysics of platinum(II) complexes bearing 2-(7-(4-R-phenylethynyl)-9,9-dihexadecyl-fluoren-2-yl)-1,10-phenanthroline ligand

A series of platinum(II) complexes bearing 2-(7-(4-R-phenylethynyl)-9,9-dihexadecyl-fluoren-2-yl)-1,10-phenanthroline ligand were synthesized and characterized. Their photophysical properties were systematically investigated by UV–Vis absorption, emission, and transient absorption spectroscopy. All complexes exhibit 1π,π∗ absorption bands below 410nm and charge transfer transitions at 415–550nm in CH2Cl2. They all emit at ca. 624nm with vibronic structures. Both UV–Vis absorption and emission spectra show negative solvatochromic effect. All complexes exhibit broad and moderately strong triplet transient absorption from the near-UV to the near-IR spectral region. Reverse saturable absorption of these complexes in CH2Cl2 for ns laser pulses at 532nm was demonstrated.