Basis Of TD-DFT Calculations Research Articles

SYNTHESIS AND MOLECULAR STRUCTURE OF TETRA-3-(4-CYCLOHEXYLPHENOXY)PHTHALOCYANINE ALUMINUM CHLORIDE COMPLEX

This work is devoted to the synthesis and study of the molecular structure of the tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride complex. The synthesis of tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride was carried out by the "nitrile" method. The complex was purified by M60 silica gel column chromatography, eluting with the chromophore. IR-spectroscopy and mass-spectrometry (MALDI-TOF) were used for the identification of the obtained compound. The electronic absorption spectrum was obtained in tetrahydrofurane and interpreted by quantum-chemical calculations in TDDFT approximation. The conformational search was performed utilizing the CREST program and GFN2-xTB approximation, followed by DFT calculations of the “single-point” energies of the found conformations. For each configuration, "single-point" energy calculations were carried out in the B3LYP-D3/dgdzvp approximation and the most energetically favorable structure was identified. It has been established that the most energetically favorable structure of the tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride molecule is characterized by a helical mutual arrangement of bulky substituents on the same side of the macrocyclic plane. The interpretation of the electronic absorption spectrum was made on the basis of TDDFT calculations in the B3LYP-D3/def2-TZVP and CAM-B3LYP/def2-TZVP approximations with and without solvent (tetrahydrofuran, THF) within the C-PCM continuum solvation model. For both approximations, taking into account the solvent leads to a shift of the long-wavelength absorption maximum by 25–33 nm towards the experimental value (704 nm). The best agreement with experiment is achieved with the [PCM] CAM-B3LYP/def2-TZVP method.The simulated electronic spectrum is compared with the previously obtained spectra for complexes of Al(Cl) with tetrabenzoporphyrin (ClAlTBP) and tetrapyrazinoporphyrazine (ClAlTPyzPA).

Luminescent Behavior of Zn(II) and Mn(II) Halide Derivatives of 4-Phenyldinaphtho[2,1-d:1',2'-f][1,3,2]dioxaphosphepine 4-Oxide and Single-Crystal X-ray Structure Determination of the Ligand.

The two enantiomers of chiral phosphonate 4-phenyldinaphtho[2,1-d:1',2'-f][1,3,2]dioxaphosphepine 4-oxide, O=PPh(BINOL), were synthesized from the proper 1,1'-bi-2-naphtol (BINOL) enantiomer and characterized. The structure of the (S)-enantiomer was elucidated by means of single-crystal X-ray diffraction. The reaction with anhydrous ZnBr2 afforded complexes having the general formula [ZnBr2{O=PPh(BINOL)}2] that showed intense fluorescence centered in the near-UV region rationalized on the basis of TD-DFT calculations. The corresponding Mn(II) complexes with the general formula [MnX2{O=PPh(BINOL)}2] (X = Cl, Br) exhibited dual emission upon excitation with UV light, with the relative intensity of the bands dependent upon the choice of the halide. The highest energy transition is comparable with that of the Zn(II) complex, while the lowest energy emission falls in the red region of the spectrum and is characterized by lifetimes in the hundreds of microseconds range. Although the emission at lower energy can also be achieved by direct excitation of the metal center, the luminescence decay curves suggest that the band in the red range is possibly derived from BINOL-centered excited states populated by intersystem crossing.

Five-coordinated bis-dioxolene cobalt complexes with triphenylphosphine

Three novel five-coordinated bis-dioxolene cobalt complexes with triphenylphosphine were synthesized. Complexes differ by dioxolene ligands: 3,6-di-tert-butylcyclohexa-3,5-diene-1,2-dione (complex 1), 5,8-di-tert-butyl-2,3-dihydro-1,4-ethanoquinoxaline-6,7-dione (complex 2), 3,6-di-tert-butyl-4-methoxycyclohexa-3,5-diene-1,2-dione (complex 3). The geometry of the inner coordination core of all compounds is close to square pyramidal. The base of the pyramid is formed by oxygen atoms of the dioxolene ligands whereas phosphine occupies the apical position. The planes of dioxolenes are slightly bent relative to each other. The magnetic moment values at low temperatures correspond to one unpaired electron per molecule for all complexes. In the complex containing a methoxy group in the dioxolene ligand (3), an increase in the magnetic moment is observed upon heating above 250 K, which indicates the appearance of a fraction of molecules with a higher spin multiplicity. A slight elongation of the Co-O, Co-P distances and shortening of the CO bonds is observed at 353 K. DFT calculations using the TPSSh functional correctly reproduce geometries of the complexes as well as their electronic absorption and vibrational spectra. DFT predicts the doublet-state complexes to possess the lowest enthalpies. Gibbs free energy of sextet complex 3 in solution is lower than that of its doublet state. This agrees well with the experimental electronic absorption spectra. On the basis of TD DFT calculations, a strong NIR absorption band in the spectra of low-spin 1 and 2 is assigned to the transition involving charge transfer from cobalt to the dioxolene and PPh3 ligands (MLCT). The doublet molecules can be described by the (↑SQ—)(Co3+)(Cat2—) ↔ (Cat2—)(Co3+)(↑SQ—) resonance structures. The sextet state in all three systems represents the (↑SQ—)(↑↑↑Co2+)(PPh3)(↑SQ—) bis-semiquinonate complex of high-spin Co(II). On the basis of the conventional description the doublet → sextet transition in complexes can be interpreted as a VT/SCO transformation. The electron density analysis of the doublet → sextet transition in the 1 and 3 molecules reveals areas of both increase and decrease in the charge density near the Co and O atoms.

Photoinduced Reductive C-C and C-Heteroatom Couplings from Bis-cyclometalated Pt(IV) Alkynyl Complexes.

Unsymmetrical dicarboxylato complexes [Pt(tpy)2(O2CR)2] [tpy = cyclometalated 2-(p-tolyl)pyridine, R = Me, CF3] react with the terminal alkynes 4-methoxyphenylacetylene, phenylacetylene, 4-(trifluoromethyl)phenylacetylene or 3,5-difluorophenylacetylene in the presence of a base to produce complexes mer-[Pt(tpy)2(O2CR)(CCAr)], in which the metalated carbon atoms are in a meridional arrangement. Irradiation of the trifluoroacetato derivatives with a 365 nm LED source leads to isomerization to the facial complexes, which can be converted to chlorido derivatives upon reaction with NH4Cl. In contrast, irradiation of the acetato derivatives leads to four different processes, namely, reduction to cis-[Pt(tpy)2], annulations involving one of the tpy ligands and the Cα and Cβ atoms of the alkynyl to give benzoquinolizinium derivatives, isomerization to the facial geometry, or C-O couplings between the acetato ligand and one tpy. The first two processes are favored by the presence of electron-donating groups on the alkynyl, whereas electron-withdrawing groups favor the last two. Irradiation of complexes fac-[Pt(tpy)2(O2CCF3)(CCAr)] with a medium-pressure Hg UV lamp leads to a reductive C-C coupling involving the alkynyl Cα atom and one of the tpy ligands to give pyridoisoindolium derivatives, except for the methoxyphenylacetylide derivative, which is photostable. On the basis of TDDFT calculations, the photoreactivity of the mer complexes is attributed to 3LLCT [π(alkynyl) → π*(tpy)] excited states for annulations or 3LMCT [π(alkynyl) → dσ*] excited states for the rest of the processes, which are accessible through thermal population from 3LC(tpy) states. The C-C couplings from the fac complexes are attributed to photoreactive pentacoordinate intermediates.

Reactivity of Li+@C60@C240 and Photoinduced Charge Shift in Li+ Doped Giant Nested Fullerenes

Over the last years, carbon nano-onions (CNOs) have been in focus in material science research. Apart from its prospective use in solar cells, the number of potential applications of CNOs have grown in the last decades. Among them, we can mention their application in gas storage processes, solid lubrication, or heterogeneous catalysis, and also as electrode materials in capacitors, anode materials in lithium-ion batteries, catalyst support in fuel cells, or electro-optical devices. From the analysis of the polarizability of CNOs, it was concluded that CNOs behave as near perfect nanoscopic Faraday cages.[1] If CNOs behave as ideal Faraday cages, the reactivity of the C240 cage should be the same in Li+@C240 and Li+@C60@C240. In the first part of this work, we have analyzed the Diels-Alder reaction of cyclopentadiene to the free C240 cage and the C60@C240 CNO together with their Li+-doped counterparts using density functional theory (DFT). We find that in all cases the preferred cycloaddition is on bond [6,6] of type B of the C240 cage. From the comparison between the reactivity of Li+@C240 and Li+@C60@C240, we conclude that C60@C240 does not act as a perfect Faraday cage.[2] In the second part of this work, we perform a systematic study of excited state properties of six double-layered Li+ doped fullerenes of Ih symmetry: [Li@C60@C240]+, [Li@C60@C540]+, [Li@C60@C960]+, [Li@C240@C540]+, [Li@C240@C960]+ and [Li@C540@C960]+. On the basis of TDDFT calculations, we show that the long-wave absorption by the Li+ doped species leads to charge transfer (CT) between the inner and the outer shells unlike their neutral double-layered precursors. The CT energy depends strongly on the size of the concentric fullerenes and it can easily be tuned by varying both the encapsulated metal ion and the size of the shells. Two types of low-lying excited states are identified (1) capacitor-like structures, as Li+@C60 -@C240 +, with alternating positive and negative charges, and (2) states, where the positive charge is delocalized over the outer shell, as in Li@C240@C540 +.[3] References [1] R. R. Zope, J. Phys. B: At. Mol. Opt. Phys. 41 (2008) 41, 085101; [b] R. R. Zope, S. Bhusal, L. Basurto, T. Baruah and K. Jackson, J. Chem. Phys. 143 (2015) 084306.[2] A. J. Luque-Urrutia, A. Poater and M. Solà. Chem. Eur. J., 26 (2020) 804-808.[3] A. J. Stasyuk, O. A. Stasyuk, M. Solà and A. A. Voityuk. J. Phys. Chem. C 123 (2019) 16525-16532. Figure 1

Femto/Picosecond Transient Absorption Study of Ring-Opening Dynamics in Perimidinespirocyclohexadienone Derivatives.

The ring-opening dynamics of perimidinespirocyclohexadienone derivatives has been studied by means of time-resolved spectroscopy in cyclohexane and acetonitrile solutions. It has been established that molecular isomerisation leading to the open isomer occurs against the background of the S1 -S0 internal conversion of the cyclic form. In addition, the features of the observed spectral changes in the cyclohexane made it possible to distinguish formation of the photoproduct in the T1 state and its relaxation via intersystem crossing to the singlet ground state. The corresponding assignments for transient absorption bands were performed on the basis of TD-DFT calculations.

(Invited) Reactivity of Li+@C60@C240 and Photoinduced Charge Shift in Li+ Doped Giant Nested Fullerenes

Over the last years, carbon nano-onions (CNOs) have been in focus in material science research. Apart from its prospective use in solar cells, the number of potential applications of CNOs have grown in the last decades. Among them, we can mention their application in gas storage processes, solid lubrication, or heterogeneous catalysis, and also as electrode materials in capacitors, anode materials in lithium-ion batteries, catalyst support in fuel cells, or electro-optical devices. From the analysis of the polarizability of CNOs, it was concluded that CNOs behave as near perfect nanoscopic Faraday cages.[1] If CNOs behave as ideal Faraday cages, the reactivity of the C240 cage should be the same in Li+@C240 and Li+@C60@C240. In the first part of this work, we have analyzed the Diels-Alder reaction of cyclopentadiene to the free C240 cage and the C60@C240 CNO together with their Li+-doped counterparts using density functional theory. We find that in all cases the preferred cycloaddition is on bond [6,6] of type B of the C240 cage. From the comparison between the reactivity of Li+@C240 and Li+@C60@C240, we conclude that C60@C240 does not act as a perfect Faraday cage.[2] In the second part of this work, we perform a systematic study of excited state properties of six double-layered Li+ doped fullerenes of Ih symmetry: [Li@C60@C240]+, [Li@C60@C540]+, [Li@C60@C960]+, [Li@C240@C540]+, [Li@C240@C960]+ and [Li@C540@C960]+. On the basis of TDDFT calculations, we show that the long-wave absorption by the Li+ doped species leads to charge transfer (CT) between the inner and the outer shells unlike their neutral double-layered precursors. The CT energy depends strongly on the size of the concentric fullerenes and it can easily be tuned by varying both the encapsulated metal ion and the size of the shells. Two types of low-lying excited states are identified (1) capacitor-like structures, as Li+@C60 -@C240 +, with alternating positive and negative charges, and (2) states, where the positive charge is delocalized over the outer shell, as in Li@C240@C540 +.[3] References [1] R. R. Zope, J. Phys. B: At. Mol. Opt. Phys. 41 (2008) 41, 085101; [b] R. R. Zope, S. Bhusal, L. Basurto, T. Baruah and K. Jackson, J. Chem. Phys. 143 (2015) 084306.[2] A. J. Luque-Urrutia, A. Poater and M. Solà. Submitted for publication.[3] A. J. Stasyuk, O. A. Stasyuk, M. Solà and A. A. Voityuk. J. Phys. Chem. C 123 (2019) 16525-16532. Figure 1

Supramolecular Tessellations by a Rigid Naphthalene Diimide Triangle.

Tessellation of organic polygons though [π···π] and charge-transfer (CT) interactions offers a unique opportunity to construct supramolecular organic electronic materials with 2D topologies. Our approach to exploring the 3D topology of 2D tessellations of a naphthalene diimide-based molecular triangle (NDI-Δ) reveals that the 2D molecular arrangement is sensitive to the identity of the solvent and solute concentrations. Utilization of nonhalogenated solvents, combined with careful tailoring of the concentrations, results in NDI-Δ self-assembling though [π···π] interactions into 2D honeycomb triangular and hexagonal tiling patterns. Cocrystallization of NDI-Δ with tetrathiafulvalene (TTF) leads systematically to the formation of 2D tessellations as a result of superstructure-directing CT interactions. Different solvents lead to different packing arrangements. Using MeCN, CHCl3, and CH2Cl2, we identified three sets of cocrystals, namely CT-A, CT-B, and CT-C, respectively. Solvent modulation plays a critical role in controlling not only the NDI-Δ:TTF stoichiometric ratios and the molecular arrangements in the crystal superstructures, but also prevents the inclusion of TTF guests inside the cavities of NDI-Δ. Confinement of TTF inside the NDI-Δ cavities in the CT-A superstructure enhances the CT character with the observation of a broad absorption band in the NIR region. In the CT-B superstructure, the CHCl3 lattice molecules establish a set of [Cl···Cl] and [Cl···S] intermolecular interactions, leading to the formation of a hexagonal grid of solvent in which NDI-Δ forms a triangular grid. In the CT-C superstructure, three TTF molecules self-assemble, forming a supramolecular isosceles triangle TTF-Δ, which tiles in a plane alongside the NDI-Δ, producing a 3 + 3 honeycomb tiling pattern of the two different polygons. Solid-state spectroscopic investigations on CT-C revealed the existence of an absorption band at 2500 nm, which on the basis of TDDFT calculations, was attributed to the mixed-valence character between two TTF•+ radical cations and one neutral TTF molecule.

Superior Sensor for Be2+ Ion Recognition via the Unprecedented Octahedral Crystal Structure of a One-Dimensional Coordination Polymer of Crown Fused Zinc Phthalocyanine.

The unprecedented one-dimensional (1-D) coordination polymer of crown fused zinc phthalocyanine (P-CfZnPc) with an octahedral crystal structure and with intermolecular packing that has superior multichannel sensor ability for Be2+ ion recognition was prepared and characterized by single-crystal X-ray diffraction analysis (XRD) and a wide range of spectroscopic and voltammetric methods. An exceptional feature of the crystal structure of P-CfZnPc is that each zinc ion in the phthalocyanine (Pc) polymer is coordinated by the four isoindole nitrogen atoms and an outer oxygen atom of the Pc molecule. This structure is the first example of an octahedral arrangement in a 1-D polymeric chain for zinc phthalocyanines (ZnPcs) and zinc porphyrins (ZnPs) reached without the presence of a coordinating solvent, which was confirmed by XRD analysis. Interestingly, this (1-D) coordination polymer preserves its conformation in THF (tetrahydrofuran) solution, thereby effectively preventing aggregation. This result was confirmed by the particle size of the molecule (125 nm) using dynamic light scattering (DLS) and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectra as well as UV-vis spectroscopy. The sensor has long-term stability (more than 3 months in solution), a very low response time (less than 1 s), and nonaggregating ability, facilitating the accurate determination of ultra-trace amounts of Be2+ (lower than 1 ppb), which is extremely important in terms of human health and environmental protection. The sensor can highly selectively and sensitively bind Be2+ among Li+, Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Al3+, Co2+, Hg2+, Ni2+, Pb2+, and Zn2+ ions via Be2+-induced J aggregation of Pc molecules. Such a binding leads to not only a significant decrease in Pc absorption (677 nm) as well as the creation of new absorption (720 nm) but also fluorescence emission quenching (690 nm). Furthermore, the sensor displayed highly selective voltammetric recognition for Be2+ following J aggregation/disaggregation in the second reduction process. The binding mechanism of the sensor and Be2+ ion was also explained on the basis of TD-DFT calculations.

4-(Diethylamino) salicylaldehyde based fluorescent Salen ligand with red-shifted emission – A facile synthesis and DFT investigation

4-(Diethylamino) salicylaldehyde based Salen ligands were synthesized and studied using density functional theory (DFT) employing B3LYP/6-31G(d) method. These dyes exhibited intramolecular charge transfer (ICT) which were examined for their photophysical properties. They show red to deep red absorption and emission respectively in the range of 562–575 nm and 596–635 nm and exhibited positive solvatochromism which is supported by linear and multi-linear regression analysis. Oscillator strengths and transition state dipole moments are studied to understand charge transfer (CT) characteristics. These deep red emissive fluorophores showed aggregation-caused quenching (ACQ). The spectral variations were analyzed by linear solvation energy relationships proposed by Kamlet-Taft and Catalan which indicated that solvent polarizability/dipolarity influences more compared to solvent acidity or basicity. Bathochromic shift in emission and increase in dipole moment in the excited state signify ICT character. The calculated electronic spectra of dyes are elucidated on the basis of TD-DFT calculations. Spectroscopic and computational methods were used to obtain linear polarizability, hyperpolarizability of the dyes and have better NLO properties than urea. Molecular Electrostatic Potential (MEP), NBO, HOMO-LUMO analysis, global chemical reactivity descriptors are studied at same level DFT.

Molecular structure, spectral studies, NBO, HOMO–LUMO profile, MEP and Mulliken analysis of 3β,6β-dichloro-5α-hydroxy-5α–cholestane

The synthesis of 3β,6β-dichloro-5α-hydroxy-5α–cholestane (in general, steroidal chlorohydrin or steroidal halohydrin) and theoretical study of the structure are reported in this paper. The individuality of chlorohydrin was confirmed by FT-IR, NMR, MS, CHN microanalysis and X-ray crystallography. DFT calculations on the titled molecule have been performed. The molecular structure and spectra explained by Gaussian hybrid computational analysis theory (B3LYP) are found to be in correlation with the experimental data obtained from the various spectrophotometric techniques. The theoretical geometry optimization data were compared with the X-ray data. The vibrational bands appearing in the FT-IR are assigned with accuracy using harmonic frequencies along with intensities and animated modes. Molecular properties like NBO, HOMO-LUMO analysis, chemical reactivity descriptors, MEP mapping and dipole moment have been dealt at same level of theory. The calculated electronic spectrum of chlorohydrin is interpreted on the basis of TD-DFT calculations.

On the consequences of the stereochemical activity of the Bi(iii) 6s2 lone pair in cyclen-based complexes. The [Bi(DO3A)] case.

We report a detailed study of the structure of the [Bi(DO3A)] complex both in the solid state and in solution. The X-ray crystal structure of [Bi(DO3A)] evidences the octa-coordination of the Bi(iii) ion, which is directly coordinated to the four nitrogen atoms of the cyclen unit and three oxygen atoms of the carboxylate groups. The octa-coordination is completed by an oxygen atom of a neighboring carboxylate group, which bridges Bi(iii) ions thanks to μ2-η1:η1 coordination, resulting in the formation of a coordination polymer. The Bi(iii) ion presents a twisted-square antiprismatic (TSAP) coordination geometry associated with the Δ(δδδδ)/Λ(λλλλ) enantiomeric pair. A computational DFT study indicates that the 6s2 lone pair of Bi(iii) is stereochemically active in [Bi(DO3A)] and most of the cyclen-based complexes reported in the literature. Depending on the spatial arrangement of the donor atoms of the ligand the lone pair points in different directions, so that Bi(iii) can easily accommodate different coordination environments. In solution the [Bi(DO3A)] complex exists as a monomeric complex, as demonstrated by DOSY measurements. The stability constant of the [Bi(DO3A)] complex, determined by using batch spectrophotometric titrations, was found to be rather high (log K = 26.85(5)). The complex presents characteristic absorption in the UV spectrum at 299 nm (ε = 8770 M-1 cm-1) that was attributed to the Bi(iii)-centered 6p ← 6s band on the basis of TDDFT calculations. Spectrophotometric titrations reveal weak binding of different anions to the [Bi(DO3A)] complex, with association constants of K11 = 3.55(8), 3.09(7), 6.2(1) and 2.19(5) for Cl-, Br-, I- and N3-, respectively.

Synthesis, molecular, electronic structure, linear and non-linear optical and phototransient properties of 8-methyl-1,2-dihydro-4H-chromeno[2,3-b]quinoline-4,6(3H)-dione (MDCQD): Experimental and DFT investigations

Base catalysed ring opening ring closure (RORC) reaction of 6-methylchromone-3‑carbonitrile (1) with 1,3-cyclohexanedione afforded 8-methyl-1,2-dihydro-4H-chromeno[2,3-b]quinoline-4,6(3H)-dione (MDCQD). Theoretical calculations by Density Functional Theory (DFT) at the B3LYP/6-311G (d,p) level of theory was utilized to illustrate the equilibrium geometries of MDCQD. Also, the nonlinear optical properties, simple harmonic vibrational frequencies, thermo-chemical parameters and Mullikan atomic charges were calculated. In addition, the electronic absorption spectra in polar and non polar solvents were discussed on the basis of TD-DFT calculations. A nanofiber-like structure with high aggregation was resolved by using scanning electron microscopy images and its particle sizes were measured by particle size analyzer. The spectroscopic characteristics of the prepared thin film of MDCQD were studied in a wide spectral range of 200–2500nm. The analysis of the absorption edges affords two direct optical band gaps with energies of 1.00 and 2.76eV. A characteristic emission peak of photoluminescence spectrum in the visible region was detected and has a red-shift as a result of solvent polarity. The MDCQD film based heterojunction showed rectification behavior and diode-like characteristics. The photovoltaic characteristics under illumination of 100mW/cm2 were studied. The open-circuit voltage and short-circuit current were found to be 0.22V and 4.25×10−7A/cm2, respectively. Moreover, the prepared heterojunction showed remarkable phototransient characteristics which afford the probability for the operation as a photodiode.

Dysprosium Heteroleptic Corrole-Phthalocyanine Triple-Decker Complexes: Synthesis, Crystal Structure, and Electrochemical and Magnetic Properties.

Two triple-decker dinuclear sandwich dysprosium complexes, which are represented as Dy2[Pc(OC5H11)8]2[Cor(FPh)3] (1) and Dy2[Pc(OC5H11)8]2[Cor(ClPh)3] (2), were synthesized and characterized by spectroscopic and electrochemical methods in nonaqueous media. Their electronic structures were also investigated on the basis of TD-DFT calculations. The sandwich triple-decker nature with the molecular conformation of [Pc(OC5H11)8]Dy[Cor(FPh)3]Dy[Pc(OC5H11)8] for compound 1 was unambiguously revealed by single-crystal X-ray diffraction analysis and showed each dyprosium ion to be octacoordinated by the isoindole and pyrrole nitrogen atoms of an outer phthalocyanine ring and the central corrole ring, respectively. In addition, the magnetic properties of both compounds have also been characterized for exploring the functionalities of these types of triple-decker complexes.

A theoretical study of the structural and electronic properties of trans and cis structures of chlorprothixene as a nano-drug

Geometrical structure, electronic and optical properties, electronic absorption spectra, thermodynamic properties, natural charge distribution, MEP analysis, and charge transfer analysis of trans and cis structures of chlorprothixene drug have been investigated with DFT and TDDFT methods. The results of the computations show that the calculated quantum quantities of the cis isomer of chlorprothixene are in agreement with the activity of cis-chlorprothixene as a drug. Cis structure of chlorprothixene has slightly better absorption properties than the trans structure on the basis of TDDFT calculations. The NLO quantities of the cis structure are higher than the trans structure, and the chemical hardness of the cis isomer, is smaller than the trans isomer which specifies that the reactivity and charge transfer of the cis structure of chlorprothixene is higher than the trans structure. The MEP maps of both conformations of chlorprothixene show that the top of the N atom and the around of the S and Cl atoms of the molecule are proper regions for electrophilic reactions. The calculated thermodynamic parameters illustrate that these parameters are improving with increasing temperature because of the enhancement of molecular vibrational intensities with temperature.

Varying Electronic Structures of Diosmium Complexes from Noninnocently Behaving Anthraquinone-Derived Bis-chelate Ligands.

The new compounds [(bpy)2Os(II)(μ-L1(2-))Os(II)(bpy)2](ClO4)2 ([1](ClO4)2) and [(pap)2Os(II)(μ-L1(2-))Os(II)(pap)2](ClO4)2 ([2](ClO4)2) (H2L1 = 1,4-dihydroxy-9,10-anthraquinone, bpy = 2,2(/)-bipyridine, and pap = 2-phenylazopyridine) and [(bpy)2Os(II)(μ-L2(•-))Os(II)(bpy)2](ClO4)3 ([3](ClO4)3) and [(pap)2Os(II)(μ-L2(2-))Os(II)(pap)2](ClO4)2 ([4](ClO4)2) (H2L2 = 1,4-diamino-9,10-anthraquinone) have been analytically identified as the meso and rac diastereoisomers, respectively. The paramagnetic [3](ClO4)3 was also characterized by crystal structure determination. In CD3CN solution, [3](ClO4)3 displays rather narrow but widely split (13 > δ > -8 ppm) resonances in the (1)H NMR spectrum, yet no EPR signal was observed down to 120 K. Cyclic voltammetry and differential pulse voltammetry reveal several accessible redox states on oxidation and reduction, showing that the replacement of 1,4-oxido by imido donors causes cathodic shifts and that the substitution of bpy by the stronger π-accepting pap ligands leads to a strong increase of redox potentials. Accordingly, system 3(n) with the lowest (2+/3+) potential was synthetically obtained in the mono-oxidized (3+) form. The (3+) intermediates display small comproportionation constants Kc of about 10(3) and long-wavelength near-infrared absorptions; an EPR signal with appreciable g splitting (1.84, 1.96, and 2.03) was only observed for 4(3+), which exhibits the smallest spin density on the osmium centers. An oxidation state formulation [Os(III)(μ-L(•3-))Os(III)](3+) with some [Os(II)(μ-L(2-))Os(III)](3+) contribution was found to best describe the electronic structures. UV-vis-NIR absorption spectra were recorded for all accessible states by OTTLE spectroelectrochemistry and assigned on the basis of TD-DFT calculations. These results and additional EPR measurements suggest rather variegated oxidation state situations, e.g., the pap ligands competing with the bridge L for electrons, while the oxidation produces mixed spin systems with variable metal/ligand contributions.

Electronic excited states of chromium and vanadium bisarene complexes revisited: interpretation of the absorption spectra on the basis of TD DFT calculations.

The nature and energies of the (arene)2Cr, (arene)2V and (arene)2Cr(+) (arene = η(6)-C6H6, η(6)-C6H5Me, η(6)-1,3-C6H4Me2, and η(6)-1,3,5-C6H3Me3) electronic excited states have been determined on the basis of the time-dependent density functional theory (TD DFT) approach and comparison with the gas-phase and condensed-phase absorption spectra. Both valence-shell and Rydberg electronic excitations were taken into account. The TD DFT results appear to describe correctly the influence of the metal atom and the ligand on the band positions and intensities in the UV-visible absorption spectra as well as the mixing of Rydberg and intravalency states. The TD DFT calculations suggest new assignments for long-wavelength valence-shell absorption bands in the spectra of (arene)2V and (arene)2Cr(+).

Synthesis, Structure, and Reactivity of Trigonal Bipyramidal Ruthenium(IV) Trialkyl Complexes

The alkylation of [Ru(NPPh3)(PPh3)2Cl3] with Me3SiCH2MgCl afforded the RuIV trialkyl complex [Ru(CH2SiMe3)3(PPh3)Cl] (1), which exhibits a trigonal bipyramidal geometry with the three alkyl groups occupying the equatorial plane. DFT calculations reveal that 1 possesses a (dxz,dyz)4 singlet ground state, consistent with the observed diamagnetism of the complex. The electronic spectrum of 1 displayed two absorptions at 455 and 505 nm, which, on the basis of TDDFT calculations, are attributed to metal-centered d–d transitions with a significant contribution from the alkyl ligands. Chloride abstraction of 1 with Ag(OTf) (OTf– = triflate) provided the triflate complex [Ru(CH2SiMe3)3(PPh3)(OTf)] (2) that proved to be a useful starting material for RuIV trialkyl complexes. Substitution of 2 with NaX afforded [Ru(CH2SiMe3)3(PPh3)(X)] (X = N3– (3) or SCN– (4)). Treatment of 2 with excess sodium 2,3,5,6-tetrafluorophenoxide (NaORf) in tetrahydrofuran resulted in desilylation of two alkyl groups, and formation of the dimethyl complex [Ru(CH2SiMe3)Me2(PPh3)(ORf)] (5). 2 underwent reductive elimination of the C–C bond with 1,10-phenanthroline (phen) in CH2Cl2 to give cis-[Ru(phen)2(PPh3)Cl](OTf) (6). The crystal structures of 1, 2, 4, and 5 have been determined.

Solid state luminescence of CuI and CuNCS complexes with phenanthrolines and a new tris (aminomethyl) phosphine derived from N-methyl-2-phenylethanamine

A new tris (aminomethyl) phosphine derived from N-methyl-2-phenylethanamine P(CH2N(CH3)CH2CH2Ph)3 (1) has been synthesized and characterized by the NMR spectra. Also, three new copper(I) iodide or isothiocyanate complexes with 1 1,10-phenanthroline (phen) and 2,9-dimethyl-1,10-phenanthroline (dmp) [CuI(phen)P(CH2N(CH3)CH2CH2Ph)3] (1P) CuI(dmp)P(CH2N(CH3)CH2CH2Ph)3] (1I) and [CuNCS(dmp)P(CH2N(CH3)CH2CH2Ph)3] (1T), have been synthesized and characterized by elemental analysis as well as studied by NMR, UV–vis, IR and luminescence spectroscopies. An X-ray structure of 1P complex revealed that the geometry around Cu(I) center in this complex is distorted pseudo-tetrahedral. Investigated complexes exhibit orange, rather weak photoluminescence in the solid state. This relatively low intensity may be related to the high flattening deformations of the molecular geometries in the excited triplet states On the basis of TDDFT calculations we confirmed that the absorbance and luminescence bands of (MX,MPR3)LCT as well as of (MX)LCT types result mainly from the transitions from the copper–iodine (or isothiocyanate) bonds and a small admixture of copper–phosphine bonds to antibonding orbitals of phen or dmp diimines.

Luminescent copper(ı) (pseudo)halide complexes with neocuproine and a novel bulky tris (aminomethyl) phosphine derived from 2-piperazinopyridine

A novel bulky phosphine derived from 2-piperazinopyridine P(CH2N(CH2CH2)2N-2-py)3 (1) and its chalcogenide derivatives (oxide, sulfide and selenide) have been synthesized and characterized by elemental analysis, NMR spectroscopy and mass spectrometry. Next, two new copper(I) iodide or isothiocyanate complexes with 1 and 2,9-dimethyl-1,10-phenanthroline (dmp): [CuI(dmp)(1)] (1I) and [CuNCS(dmp)(1)] (1T), have been also synthesized and characterized by elemental analysis and studied by NMR, UV–vis, IR and luminescence spectroscopies. The X-ray structure of the complex 1T·1.81(CH3COCH3) was determined. The coordination geometry around the Cu(I) center is pseudo-tetrahedral with distortions resulting mostly from the molecular packing in the crystal cell. Both complexes exhibit orange photoluminescence in the solid state, which is much stronger for 1I than for 1T. The luminescence spectra of both complexes at room and 77K temperatures show relatively large bands with a typical batochromic shift accompanying the lowering of the temperature. On the basis of TDDFT calculations we interpreted these bands as of (MX,MPR3)LCT type resulting mainly from the transitions from the copper–iodine (or isothiocyanate) bonds and a small admixture of copper–phosphine bonds to antibonding orbitals of dmp diimine.