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Photolysis of thioureido derivatives of cymantrene in solution and solvent-free affords stable six-membered dicarbonyl chelates due to coordination of sulfur of the C═S group to manganese. The proc...

1N- and 2N-cymantrenylalkylsubstituted 1,2,3-triazoles were for the first time synthesized. It was found that irradiation by a mercury lamp light with λ = 365 nm of cymantrenylalkyl-1,2,3-triazoles 3, 5–8 gives stable dicarbonyl chelates 4, 9–12. In a closed system without CO removal, intermolecular photochromic systems between tricarbonyl and dicarbonyl complexes were formed; half-conversion time for the dark reaction was more than 10 h. The effect of a substituent position in dicarbonyl chelates 4, 9–12 on the parameters of their spectra, coordination ability of the N atom and chemical stability was studied. It was found that coordination ability of the nitrogen atoms markedly depends on steric hindrances, which are significantly different in 1N- and 2N-substituted triazoles.

The synthesis of new quinazoline derivatives with 2,3- and 4-positioned cymantrenyl fragment is described. Alkylation of 2-substituted quinazolin-4-ones with cymantrenylalkyl bromides on using K2CO3, potassium tert-butoxide, and sodium hydride as bases has been studied. It is established for the first time that condensation of 2-methylquinazolin-4-ones with aldehydes can cause elimination of the substituent at the nitrogen atom in position 3. The new cymantrene derivatives possess fluorescence properties.

The synthesis of novel push–pull 2,4-disubstituted quinazolines was performed by the bromodeoxygenation of 2-phenyl-, 2-(fluoren-2-yl)- and 2-cymantrenylquinazolin-4-ones and subsequent palladium-catalyzed Suzuki reactions. According to the optical studies, derivatives containing 4-positioned 4-diethylaminophenyl substituent exhibit higher luminescence in toluene solutions as compared to acetonitrile ones.

The synthesis of four new 1,2,3-triazole derivatives and seven 1,2,3-triazolium salts that contain an organometallic group (i.e., cymantrenyl and ferrocenyl) at either the N-1, N-2, or N-3 position was realized. The alkylation of organometallic and organic triazole derivatives was investigated, and as a result of these studies, it was found that the presence of a good leaving group at the heterocyclic nitrogen atom led to transalkylation and subsequent migration of the N-1 substituent to the N-2 position of the triazole moiety. The nucleophilicity of the counterion of the triazolium salt influenced the transalkylation and isomerization processes, which suggests that the elimination of the N-substituent most likely occurs though a concerted mechanism with nucleophilic assistance from the counterion. Thus, a new approach to the synthesis of 2,4-disubstituted 1,2,3-triazoles has been developed.

Photolysis of carboxamides of the dendrite structure with aminomethyland 1-aminoethylcymantrenes leads to the formation of six-membered dicarbonyl chelates with the Mn—O bond which are stable in solutions. The chelates in the reversed dark reaction with carbon monoxide give the starting tricarbonyl complexes. The formation of the chelates and their dark reaction are accompanied by the reversible change of color by the compounds. The rate determining step of the thermal reaction of chelates with CO is a chelate ring opening with the ligand substitution by the SN1 mechanism. A possibility of solvent-free photoinduced ligand-exchange reaction in a number of cymantrene derivatives was demonstrated.

The photochemical behavior of a series of monoand bifunctional derivatives of cymantrene with a triazole ring in the substituent was studied. It was shown for the first time that triazoles and triazolium salts can function as efficient n-donor ligands in the formation of cyclopentadienyl manganese dicarbonyl chelates.

Photolysis of carboxamides with aminomethyl-, 1-aminoethyl-, and aminobenzylcymantrenes led to six-membered dicarbonyl chelates with the Mn—O bond, which are stable in solutions. In the presence of carbon monoxide, the chelates undergo a dark reverse reaction with the formation of the starting tricarbonyl complexes. It was found that the rate determining step of the thermal reaction of the chelates with CO was the chelate ring opening according to the S N1 mechanism of ligand substitution.

The orientation in the metalation of monosubstituted carbamate-, amide-, ureido-, and allyl-containing derivatives of cymantrene was determined for the first time. The data obtained open up a synthetic route to polyfunctional 1,2- and 1,3-disubstituted cymantrenes. They can serve as the starting materials for the preparation of chelate complexes of (dicarbonyl)-(cyclopentadienyl)manganese, which hold promise as novel organometallic photochromes. A method for the synthesis of earlier unknown chiral derivatives of cymantrene with a quaternary carbon atom in position 1 of the side chain was proposed.

Photochemical properties of a series of bifunctional monosubstituted derivatives of cymantrene containing a C-, N-, or O-bound π-allyl group, along with n-donating carbamate, amide, or pyridine fragments were investigated. The results obtained demonstrate that the nature and thermodynamic stability of the cyclopentadienylmanganese dicarbonyl chelates derived from bifunctional monosubstituted cymantrene derivatives depend substantially on both the nature of the functional groups and on their position in the substituent at the Cp ring. Thus, for the six-membered chelates, the thermodynamic stability increases in the series carbamates < amides < pyridines < olefins. Some of the dicarbonyl chelates studied form reversible photochromic systems due to linkage isomerization between different donating groups of the bifunctional substituent and the manganese atom with a wide range of times of thermal isomerization.

Procedures were developed for preparation of optically active dendrones and dendrimers with terminal 1,2-hydroxylimino, 1,2-hydroxylamino and oxazolidinyl groups containing ether bonds in the branches and ester bonds in the backbone of the macromolecule. The compounds described may serve as chiral ligands for asymmetric metallocomplex catclysis.

Photochemical properties of cymantrene carbamates were for the first time investigated. It was found that UV irradiation of Boc-substituted 1-aminoalkylcymantrenes yields dicarbonyl chelate complexes as a result of the coordination of the oxygen atom of the carbamate ligand to the manganese atom. These complexes show high thermodynamic and kinetic stability in solution at room temperature and in closed systems can be used for the creation of photochromic systems based on cymantrene carbamates.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Series of chiral monodentate phosphite-type ligands has been evaluated in the rhodium-catalyzed asymmetric hydrogenation of dimethyl itaconate in both dichloromethane and supercritical CO 2 . High reactivities (100% conversion in 1.5–3 h) and enantioselectivities (up to 90%) were obtained in the hydrogenation in scCO 2 .

The planar chiral diaryl phosphorimidite ligand containing additional C-stereocenters and neutral and cationic palladium(II) chelates with this ligand, cis-[Pd(η2-P,N)Cl2] and [Pd(Allyl)(η2-P,N)]BF4, were synthesized for the first time. The possibility of using these compounds in asymmetric allylic alkylation of 1,3-diphenylallyl acetate with dimethyl malonate in an optical yield of up to 73% was demonstrated.

Optically active phosphite-type ligands with planar chirality have been synthesized for the first time. The new cymantrene-based P,N-iminodiamidophosphites demonstrated high enantioselectivity in the Pd-catalyzed allylic substitution of 1,3-diphenylallyl acetate with dimethyl malonate (up to 94% ee), pyrrolidine (up to 78% ee) and sodium para-toluene sulfinate (up to 84% ee).

Photochemical properties of N-acyl-substituted aminomethyl- and 1-aminoethylcymantrenes were studied for the first time. These compounds form photochromic systems in solutions due to the intermolecular exchange of ligands at the manganese atom.

A method for preparation of dendrons and dendrimers with formyl groups at the terminal aromatic rings, ether bonds in the branching blocks, and ester bonds in the core of the macromolecules is proposed. A way for the selective synthesis of p-hydroxymethylbenzaldehyde is described.

The relaxation of the Q1(π—π*) excited state of the nonprotonated Fc4PH2 and diprotonated Fc4PH4 2+ forms of meso-tetraferrocenylporphyrin was studied by femtosecond laser absorption spectroscopy. Transition from the Q1(π—π*) state to the charge-transfer state was shown to occur within 208±10 fs for Fc4PH2 and 9±3 ps for Fc4PH4 2+. A fast vibrational relaxation with a characteristic time of 120—140 fs was found for both forms. The relaxation time of Fcδ+—Pδ– charge-transfer state for Fc4PH2 was 17±4 ps.

A series of chiral phosphite-type ligands has been evaluated in the iridium-catalyzed asymmetric hydrogenation of acyclic arylimines in supercritical CO 2 . High reactivities (100% conversion in 50–120 min) and enantioselectivities (up to 95%) were obtained.

It was found that the quantum yield of the fluorescence ofmeso-tetraferrocenylporphyrin (TFcP) is at most 3.0·10−5, and that of the triplet state of FTcP is at least 200 times lower than the quantum yield ofmeso-tetraphenylporphyrin (TPP). Excitation of TFcP in CCl4 by light with λ>410 nm results in the oxidation of TFcP. The singlet and triplet excited states of TPP in toluene and acetonitrile are quenched by ferrocene with rate constants of 1.2·1010 and 1.7·1010, (4.6±0.5)·108 and (1.37±0.21)·109 L mol−1 s−1, respectively. The quenching mechanisms are discussed.

Solid-state photochemical ligand exchange in silica gel-supported π-complexes of transition metals has been demonstrated for the first time for cymantrene compounds. The method suggested allows the synthesis of monophosphine complexes to be carried out on preparative and analytical scales.

A series of P-chiral monodentate diamidophosphite ligands of the 1,3-diaza-2-phosphabicyclo[3.3.0]octane family was tested in the Rh-catalyzed hydrogenation of dimethyl itaconate and addition of phenylboronic acid at the carbonyl group of trans-cinnamaldehyde. The enantioselectivities and conversions of these reactions are strongly dependent on the nature of the exo-cyclic substituent of the ligand.

A series of mixed porphyrins with different numbers of metallocenyl (ferrocenyl and cymantrenyl) and aryl (Ph and C6F5) groups at themeso-positions was obtained and characterized by1H NMR, electronic absorption, and mass spectra. The downfield shift of NH signals as well as the bathochromic shift ofQ-bands can be attributed to a distortion of the porphyrin macrocycle upon the introduction of bulkymeso-substituents.

A new preparative method for the synthesis of Schiff bases by the solid-state interaction of crystalline organic and organometallic aldehydes and amines is suggested. The possibility of direct synthesis of aldimines in the solid state from amine salts without isolation of the free amines is demonstrated.

A number of organic and organometallic aldehydes have been converted into optically active oxazolidines by solid-state interaction with (-)-ephedrine and (+)-pseudoephedrine. The stereoselectivity of the solid-state reaction is compared with that in boiling ethanol solution.

The reaction of dicymantrenyl ketone with the Grignard reagent 2,4,6-Me3C6H2MgBr in THF occurs as the insertion of the mesityl substituent in the α-position of one of the cyclopentadienyl rings to give (2-mesitylcymantrenyl) cymantrenyl ketone (4), rather than as addition at the C=O group. Reduction of4 by NaBH4 in a THF-EtOH mixture affords (2-mesitylcymantrenyl)cymantrenylmethanol (5). Ionic hydrogenation of5 with the HSiEt3/CF3COOH system gives (2-mesitylcymantrenyl)cymantrenylmethane (7). The structure of alcohol5 has been established by X-ray diffraction analysis.

A series of chiral phosphite-type ligands has been evaluated in the iridium-catalyzed asymmetric hydrogenation of acyclic arylimines in supercritical CO 2 . High reactivities (100% conversion in 50–120 min) and enantioselectivities (up to 95%) were obtained.

A series of mixed porphyrins with different numbers of metallocenyl (ferrocenyl and cymantrenyl) and aryl (Ph and C6F5) groups at themeso-positions was obtained and characterized by1H NMR, electronic absorption, and mass spectra. The downfield shift of NH signals as well as the bathochromic shift ofQ-bands can be attributed to a distortion of the porphyrin macrocycle upon the introduction of bulkymeso-substituents.

The solid-state interaction of the three-component mixtures (ferrocenylcarbaldehyde: methyl ester of amino acid hydrochloride: K2CO3) afforded new optically active Schiff bases.

Organometallic derivatives of 2,3-dihydroperimidine were obtained by the solid state interaction of ferrocene-, cymantrene-, and ruthenocenecarbaldehydes with 1,8-naphthylenediamine.

On the basis of IR spectra and molecular mechanics calculations, the conformations stabilized by hydrogen bonding in α-carbinol derivatives of cyclopentadienyltricarbonyl manganese and rhenium have been determined. Intramolecular H-bonds with Mn and Re atoms are found in the tertiary carbinols. Relative stability of the OH ⋯ M hydrogen bonds increases in accordance with metal basicity (Mn

With the aim of modifying solid dendrite structures, the solid-state reactions of (S)-(−)-(1-trimethylammonio)ethylferrocene iodide with substituted phenols were studied.

Redox properties of H(2)TFcP [TFcP(2-) = 5,10,15,20-tetraferrocenylporphyrin(2-)] were investigated using cyclic voltammetry, differential pulse voltammetry, and square-wave voltammetry methods in a large variety of solvents and electrolytes. When DMF, THF, and MeCN were used with TBAP as the supporting electrolyte, the first oxidation wave was assigned to a single four-electron oxidation process reflecting simultaneous oxidation of all iron(II) centers into iron(III) centers in H(2)TFcP. When an o-DCB (1,2-dichlorobenzene)/TBAP combination was used in electrochemical experiments, four ferrocene substituents underwent two very diffuse, "two-electron" stepwise oxidations. The use of a weakly coordinating TFAB ([NBu(4)][B(C(6)F(5))(4)]) electrolyte in o-DCB or DCM results in four single-electron oxidation processes for ferrocene substituents in which the first and second single-electron waves have a relatively large separation, while the second, third, and fourth oxidation processes are more closely spaced; similar results were observed when a DCM/TBAP system and an imidazolium cation-based ionic liquid ((bmim)Tf(2)N = N-butyl-N'-methylimidazolium bis(trifluoromethanesulfonyl)imide) were used. Spectroelectrochemical oxidation of H(2)TFcP in o-DCB or DCM with TFAB as the supporting electrolyte allowed for characterization of the mixed-valence [H(2)TFcP](+), [H(2)TFcP](2+), and [H(2)TFcP](3+) compounds by UV-vis spectroscopy in addition to the "all-Fe(III)" [H(2)TFcP](4+). The chemical oxidation of H(2)TFcP was tested using a variety of oxidants which resulted in formation of mixed-valence [H(2)TFcP](+) and [H(2)TFcP](2+) as well as [H(2)TFcP](4+), which were characterized by UV-vis-NIR, MCD, IR, Mossbauer, and XPS spectroscopy. The intervalence-charge-transfer bands observed in the near-IR region in [H(2)TFcP](+) and [H(2)TFcP](2+) complexes were analyzed using Hush formalism and found to be of class II (in Robin-Day classification) character with localized ferrous and ferric centers. Class II behavior of [H(2)TFcP](+) and [H(2)TFcP](2+) complexes was further confirmed by Mossbauer, IR, and XPS data.

The solid-state interaction of the three-component mixtures (ferrocenylcarbaldehyde: methyl ester of amino acid hydrochloride: K2CO3) afforded new optically active Schiff bases.

H(2)TFcP [TFcP = 5,10,15,20-tetraferrocenyl porphyrin(2-)] was prepared by a direct tetramerization reaction between pyrrole and ferrocene carbaldehyde in the presence of a BF(3) catalyst, while the series of MTFcP (M = Zn, Ni, Co and Cu) were prepared by a metallation reaction between H(2)TFcP and respective metal acetates. All compounds were characterized by UV-vis and MCD spectroscopy, APCI MS and MS/MS methods, high-resolution ESI MS and XPS spectroscopy. Diamagnetic compounds were additionally characterized using (1)H and (13)C NMR methods, while the presence of low-spin iron(ii) centers in the neutral compounds was confirmed by Mössbauer spectroscopy and by analysis of the XPS Fe 2p peaks, revealing equivalent Fe sites. XPS additionally showed the influence on Fe 2p binding energies exerted by the distinct central metal ions. The conformational flexibility of ferrocene substituents in H(2)TFcP and MTFcP, was confirmed using variable-temperature NMR and computational methods. Density functional theory predicts that alpha,beta,alpha,beta atropisomers with ruffled porphyrin cores represent minima on the potential energy surfaces of both H(2)TFcP and MTFcP. The degree of non-planarity is central-metal dependent and follows the trend: ZnTFcPH(2)TFcP approximately CuTFcPCoTFcPNiTFcP. In all cases, a set of occupied, predominantly ferrocene-based molecular orbitals were found between the highest occupied and the lowest unoccupied, predominantly porphyrin-based molecular orbitals. The vertical excitation energies of H(2)TFcP were calculated at the TDDFT level and confirm the presence of numerous predominantly metal-to-ligand charge-transfer bands coupled via configurational interaction with expected intra-ligand pi-pi* transitions.

A series of P-chiral monodentate diamidophosphite ligands of the 1,3-diaza-2-phosphabicyclo[3.3.0]octane family was tested in the Rh-catalyzed hydrogenation of dimethyl itaconate and addition of phenylboronic acid at the carbonyl group of trans-cinnamaldehyde. The enantioselectivities and conversions of these reactions are strongly dependent on the nature of the exo-cyclic substituent of the ligand.

Novel chiral monodentate phosphite ligands bearing cymantrene fragment have been prepared. Phosphite 4 with PPh3, instead of CO-ligand, in cymantrene moiety provided higher enantioselectivity than its unsubstituted analogue 3 in hydrogenation of (Z)-methyl-2-acetamido-3-phenylacrylate.

The solid-state reactions of crystalline ferrocenyl- and ruthenocenylaldehydes with optically active primary β-hydroxyamines were studied at ∼20 °C. The yield of the products increases substantially in the presence of K2CO3. The tautomeric equilibrium between imines and diastereomeric oxazolidines with the predominant formation of one of them is established in solutions of the products in CDCl3.

The reaction of pyrrol with cymantrenecarboxaldehyde in acetic acid results in 5,10,15,20-tetracymantrenylporphyrin (1) and 5,10,15-tricymantrenylcorrol (2). Porphyrin synthesis according to Lindsey's method only affords compound 1 in high yield. The NH-tautomerism in molecules 1 and 2 was investigated by dynamic NMR spectroscopy. It was shown that free rotation of the (CO)3MnC5H4 fragments around the bond with the carbon atoms in themeso-positions of the porhpyrin macrocycle occurs.

With the aim of modifying solid dendrite structures, the solid-state reactions of (S)-(−)-(1-trimethylammonio)ethylferrocene iodide with substituted phenols were studied.