A semiempirical study of heterocycle oligomers and polymers in different dielectric media

Four common five-membered heterocycles—pyrrole, phosphole, thiophene, and furan—and their oligomers with the chain length of 2, 4, 6, and 10 units have been studied quantum chemically using the semiempirical PM 3 parameterization. The oligomers of pyrrole and phosphole with the homolytically dissociated N? H bond and P? H bond, respectively, and oligomers of thiophene and furan with one electron removed per monomer unit (4n + 2 π-electron bipolaron systems) have also been studied. The electronic properties of the respective polymers were extrapolated from the oligomer data. Bulk polymer effects on the electronic structure were modeled using the self-consistent reaction field theory in the multicavity approximation (MC a SCRF ). © 1995 John Wiley & Sons, Inc.     

Synthesis and Structure–Property Relationships of 2,2′‐Bis(benzo[b]phosphole) and 2,2′‐Benzo[b]phosphole–Benzo[b]heterole Hybrid π Systems

The first comprehensive study of the synthesis and structure–property relationships of 2,2′‐bis(benzo[b]phosphole)s and 2,2′‐benzo[b]phosphole–benzo[b]heterole hybrid π systems is reported. 2‐Bromobenzo[b]phosphole P‐oxide underwent copper‐assisted homocoupling (Ullmann coupling) and palladium‐catalyzed cross‐coupling (Stille coupling) to give new classes of benzo[b]phosphole derivatives. The benzo[b]phosphole–benzo[b]thiophene and ‐indole derivatives were further converted to P,X‐bridged terphenylenes (X=S, N) by a palladium‐catalyzed oxidative cycloaddition reaction with 4‐octyne through the C_β? H activation. X‐ray analyses of three compounds showed that the benzo[b]phosphole‐benzo[b]heterole derivatives have coplanar π planes as a result of the effective conjugation through inter‐ring C? C bonds. The π–π* transition energies and redox potentials of the cis and trans isomers of bis(benzo[b]phosphole) P‐oxide are very close to each other, suggesting that their optical and electrochemical properties are little affected by the relative stereochemistry at the two phosphorus atoms. The optical properties of the benzo[b]phosphole–benzo[b]heterole hybrids are highly dependent on the benzo[b]heterole subunits. Steady‐state UV/Vis absorption/fluorescence spectroscopy, fluorescence lifetime measurements, and theoretical calculations of the non‐fused and acetylene‐fused benzo[b]phosphole–benzo[b]heterole π systems revealed that their emissive excited states consist of two different conformers in rapid equilibrium.     

Derives α-carbonyles et “aromaticite” des phospholes trivalents

A two-step synthesis of 2-acetyl and 2-carbethoxy-phospholes involves the metalation of monomeric 3,4-dimethyl phosphole sulfides by t-butyl-lithium followed by reaction with ethyl acetate and ethyl carbonate. The phosphole sulfides thus obtained are reduced by PBu₃ or P(CH₂CH₂CN)₃ to the phospholes 20–24. In the 2-acetyl-phosphole series, variable electron transfer from the dienic system and from the phosphorus atom to the carbonyl group is monitored by ¹H and ³¹P NMR. The main decomposition path of 2-carboxy phosphole 25 in the mass spectrometer involves a PC intracyclic bond cleavage with loss of CO, in sharp contrast with pyrrole and thiophene derivatives 26 and 27. These facts militate against strong 2p_π–3p_π electronic delocalisation in the phosphole nucleus.     

Synthesis of π‐conjugated polymer containing both thiophene and phosphole sulfide in the main chain by simultaneous post‐element transformation of organotitanium polymer

The synthesis and unique optoelectronic features of a π‐conjugated polymer containing both thiophene and 1‐phenylphosphole sulfide units (multiple heteroles) in the main chain by the post‐element transformation of a regioregular organometallic polymer possessing titanacyclopentadiene‐2,5‐diyl unit are described. The π‐conjugated polymer containing multiple heteroles was obtained in 73% yield by the simultaneous reaction of the organotitanium polymer with sulfur monochloride and dichlorophenylphosphine (0.6 equiv each), whose number‐average molecular weight (M_n) and the molecular‐weight distribution (M_w/M_n) were estimated to be 11,000 and 3.4, respectively, by the size exclusion chromatography (SEC). The π‐conjugated polymer thus obtained was found to have the high HOMO and the low LUMO energy levels due to the electron‐rich thiophene and electron‐deficient phosphole sulfide units, respectively, as supported by its cyclic voltammetry (CV) analysis. Compared to a mixture of a polymer containing sole thiophene‐unit and that containing sole phosphole sulfide units, the π‐conjugated polymer‐containing multiple heteroles proved to exhibit interesting optical properties. For example, a specific emission peak was observed at 608 nm in the photoluminescence spectrum, which was not observed in the case of the thiophene‐containing polymer, the phosphole‐containing polymer, and their mixture. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2519–2525     

Synthesis and Structure–Property Relationships of Phosphole‐Based π Systems and Their Applications in Organic Solar Cells

Phosphole is a chemically tunable heterole, and its π‐conjugated derivatives are potential candidates for optoelectronic materials. This account describes recent developments in the synthesis and structure–property relationships of π‐conjugated phosphole derivatives made by my research group. Thiophene–phosphole–styrene, phosphole–acetylene–arene, oligophosphole, polyphosphole, areno[c]phosphole, and phosphole–heterole π systems are synthesized using titanacycle‐mediated metathesis and palladium‐catalyzed cross‐coupling reactions. The structural, optical, and electrochemical properties of selected compounds are discussed. Initial results on some applications of thiophene–phosphole copolymers, acenaphtho[c]phospholes, and amine–terthiophene–phosphole donor–π–acceptor dyes in organic solar cells are described. These results give valuable information and guidelines for designing new phosphorus‐containing organic materials for molecular electronics.     

Synthesis and characterization of tribenzyltin heteroaromatic carboxylates and crystal structure of tribenzyltin 4‐pyridinecarboxylate

Reaction of tribenzyltin chloride with 2‐furan‐, 2‐(2‐furanyl)‐vinyl‐, 2‐(5‐t‐butyl) furan‐, 2‐thiophene‐, 2‐pyridine‐, 3‐pyridine‐, 4‐pyridine‐, 3(1H)‐indole‐, 3(1H)‐indolylmethyl‐or 3‐[3(1H)‐indolyl]propyl‐carboxylate in 1:1 stoichiometry yielded tribenzyltin heteroaromatic carboxylate (PhCH₂)₃‐SnO₂CR. All compounds were characterized by elemental analysis, IR, ′H NMR and MS. The crystal structure of tribenzyltin 4‐pyridinecarboxylate was determined by single crystal X‐ray diffraction. In the crystal of tribenzyltin 4‐pyridinecarboxylate, the tin atoms are five‐coordinated in a trigonal bipyramidal structure with a linear polymer containing Sn–‐O bond with length of 0. 2142(2) nm and Sn–‐N bond with length of 0.2563(4) nm.     

Reaction between Furan‐ or Thiophene‐2‐carbonyl Chloride,Isocyanides, and Dialkyl Acetylenedicarboxy­lates: Multicomponent Synthesis of 2,2′‐Bifurans and 2‐(Thiophen‐2‐yl)furans

An efficient multi‐component synthesis of highly functionalized 2,2′‐bifurans and 2‐(thiophen‐2‐yl)furans is described. A mixture of furan‐ or thiophene‐2‐carbonyl chloride, an isocyanide, and a dialkyl acetylenedicarboxylate undergoes a smooth addition reaction in dry CH₂Cl₂ at ambient temperature to produce 2‐amino‐5‐(4‐chlorofuran‐2‐yl)furan‐3,4‐dicarboxylates and 2‐amino‐5‐(4‐chlorothiophen‐2‐yl)furan‐3,4‐dicarboxylates. A single‐crystal X‐ray‐analysis of a derivative conclusively confirms the structure of these 2,2′‐bifurans and 2‐(thiophen‐2‐yl)furans. A novel electrophilic aromatic substitution reaction can justify the formation of the Cl‐substituted furan or thiophene rings.     

Synthesis and characterization of the substituted products from the reaction of a bulky phosphite with [Os3(CO)12]

Reaction of (acetonitrile)-undeca(carbonyl)-tri-osmium and tris(2,4-di-tert-butylphenyl) phosphite yielded the phosphite clusters [Os₃(CO)₁₁L] (4) and [Os₃(CO)₁₀L₂] (5) [L = P(O-2,4- ^t Bu₂C₆H₃)₃]. These compounds were characterized spectroscopically and the molecular structure of 5 was determined by single crystal X-ray diffraction, the first reported structural analysis of a tri-osmium cluster containing aromatic phosphite ligands. Compound 5 crystallized in the triclinic space group P 1, and revealed an equatorial trans–trans position of the bulky phosphite ligands.     

Friedel-Crafts acylation of W(CO)5-complexes of azaferrocenes

Blocking of the lone pair of electrons on the nitrogen in azaferrocene by co-ordination to the W(CO)₅ moiety enables Friedel-Crafts acylation of this heteroferrocene. W(CO)₅-complexes of azaferrocene and 2,5-dimethylazaferrocene react with acetyl- and propionyl chloride or acetic anhydride in the presence of aluminium chloride in dichloromethane at r.t. to give W(CO)₅-complexes of 1′-acylazaferrocenes in 10-50% isolated yields. The low yields presumably result from instability of the products in the reaction medium. The X-ray structure of the complex of 1′-acetylazaferrocene has been determined.     

Crystal and Molecular Structure of Tricarbonyl-[(1R*, 4S*, 4aS*, 9aR*)-1,4-epoxy-2, 3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene]iron

The thermal cyclodimerization of 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene assisted by Fe₂ (CO)₉ gives the title complex 1 , a precursor for the synthesis of antitumoral anthracyclinones. The crystal structure of 1 has been determined by X-ray diffraction: a = 11.188 (1); c = 26.968 (3) Å; space group tetragonal, P4₁2₁2, Z = 8; R = 0.041; R_W = 0.033. The tricarbonyliron group is in the exo-position and the coordination polyhedron is tetragonal pyramidal. The NMR coupling constants are well-related to the observed dihedral angles between the non-aromatic protons and now give a reliable criterion for assigning the stereochemistry of the metal in d⁸-complexes of 2,3-dimethylidene-7-oxanorbornane derivatives.     

Cyclopenta[b]thienyl Ligand in Organometallic Chemistry. Synthesis of Cyclopenta[b]thiophene η5-Complexes with Metal Coordination at the Thiophene Ring

Unlike isoelectronic ⁶-indenyl ruthenium, manganese, and chromium complexes, heating of Mn(CO)₅OTf, [Ru(Cp^*)Cl₄], and Cr(C₁₀H₈)(CO)₃ with isomeric 2-ethyl-5-methylcyclopenta[b]thiophenes leads to the corresponding ⁵-complexes where the metal is coordinated at the C₅-carbocycle. The structure of the complex Mn(Th)(CO)₃ (Th = 2-ethyl-5-methylcyclopenta[b]thienyl) was proved by X-ray analysis.     

Crystal structure,electrochemical, and antibacterial activity of the sodium complex formed by o-vanillin salicylhydrazone

The mononuclear sodium(I) complex [NaL(HL)] (1) [where HL is (OH)C₆H₄–CO–HN–N=CC₆H₃(OMe)(OH) synthesized by condensation of o-vanillin and salicyloylhydrazine] has been prepared and characterized by IR, elemental analysis, single crystal X-ray diffraction, and cyclic voltammetry. Single crystal X-ray diffraction analysis reveals that NaL(HL) is a neutral complex. Each six-coordinate Na(I) in the unit is linked through O bridges forming a ladder-like arrangement of the 1-D Na(I) double chain. The oxidation–reduction processes have been determined in CH₃CN by cyclic voltammetry. The complex displayed two quasi-reversible reduction couples and one oxidation response between +1.0 and ?0.6 V. The trend in the half wave potentials reflects the electronic nature of the hydrazone ligand. The antibacterial activity results show that the complex possesses strong inhibition activity against Staphyloccus aureus and Bacillus subtilis.     

Steric hindrance in the synthesis and properties of the dimer of 1-(2,4,6-Tri-tert-butylphenyl)phosphole 1-oxide

Steric hindrance was observed during the oxidation of 2,4,6-tri-tert-butylphenylphosphole to the P oxide and in the dimerization of this latter species to the corresponding phosphanorbornene derivative. Single-crystal X-ray analysis of the dimer revealed considerable steric crowding around the P atoms. Deoxygenation of the dimer of the phosphole oxide by Cl₃SiH–C₆H₅N could only be accomplished under forcing conditions at 110°C. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 527–531, 1997     

Two tetrahydrofuran solvates of HN(SePPh2)2

The X‐ray crystal structures of P,P′‐imino­bis­(di­phenyl­seleno­phosphine) tetra­hydro­furan solvate, C₂₄H₂₁NP₂Se₂·C₄H₈O, (I), and bis­(tetra­hydro­furan) solvate, C₂₄H₂₁NP₂Se₂·2C₄H₈O, (II), have been determined; (I) has twofold crystallographic symmetry. In each compound, the O atom of one mol­ecule of tetra­hydro­furan is hydrogen bonded to the amide‐H atom of HN(SePPh₂)₂. The conformation of the Se—P—N—P—Se chains in (I), (II), and the crystal structure of the unsolvated HN(SePPh₂)₂ are different.     

Activity of catalysts in thiophene synthesis from furan and hydrogen sulfide

Thiophene synthesis from furan and H₂S over acid catalysts is reported. Proton donor catalysts are low-active, nonselective, and prone to deactivation. Alumina-supported catalysts having Lewis acid sites, such as alumina-supported catalysts, are more efficient. With these catalysts, the thiophene formation rate per Lewis acid site increases with increasing site strength. It is assumed that the reaction proceeds via the formation of a surface intermediate consisting of an acid site bonded to an α carbon atom of the furan ring and an H₂S molecule nondissociatively adsorbed on a basic site. At atmospheric pressure, T = 250–450°C, initial furan concentrations of 1–20 vol %, and H₂S/furan = 0.4–20 (mol/mol), the thiophene formation reaction is first-order with respect to both reactants and its rate constant increases with increasing temperature. The thiophene formation rate depends on the H₂S/furan molar ratio. Under optimal conditions, the thiophene yield is 95–98 mol % and the thiophene formation rate is high.     

Synthesis and Transformations of 2,4,4,7-Tetramethyl-4-silanaphtho[3,2-b]thiophen-9-one

The catalytic dehydrocyclization of dimethyl(5-methyl-2-thienyl)(2,4-dimethylphenyl)silane accompanied by a skeletal rearrangement gives 2,4,4,7-tetramethyl-4,9-dihydro-4-silanaphtho[3,2-b]thiophene, which was oxidized to 2,4,4,7-tetramethyl-4-silanaphtho[3,2-b]thiophen-9-one, whose structure was solved by X-ray diffraction structural analysis. Various chemical transformations of the ketone synthesized were performed including radical bromination by bromosuccinimide, condensation with furfural in the presence of KOH, reduction by LiAlH₄, and nitration by acetyl nitrate.     

Reaction of terminal phosphinidene complexes with aldimines: Synthesis of the first 1,2,3-azadiphosphetidine

Transient terminal phosphinidene complexes [RP-M(CO)₅] (M = Mo, W, R = Ph, Me), as generated from the corresponding 7-phosphanorbornadiene complexes, react with N-methyl(benzylidene)amine to afford the diazaphospholane complexes 3,4 (R = Ph) or a mixture of diazaphospholane 9 and 1,2,3-azadiphosphetidine 10 (R = Me), probably by insertion of either one molecule of imine or one molecule of phosphinidene into the weak P N bond of the unstable intermediate azaphosphiridine 11. The new complex 10 has been submitted to an X-ray crystal structure analysis. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9: 597–600, 1998     

Complex formation between nickel(0) and a phosphaalkene: Influence of the second ligand on the η1- and η2-coordination mode

The η²-complex (bipy)Ni(XyPCPh₂) has been prepared and its structure determined by X-ray analysis. In contrast, Ni(CO)₄ forms η¹ -complexes by replacement of one or two CO ligands by XyPCPh₂.     

以吡啶-2,5-二羧酸或噻吩-2,5-二羧酸为配体的过渡金属配合物的合成、晶体结构及性质

以吡啶-2,5-二羧酸(2,5-pyridinedicarboxylic acid,H_2L_1)、噻吩-2,5-二羧酸(Thiophene 2,5-dicarboxylic acid,H_2L_2)为主要配体,4,4′-联吡啶(4,4′-bipy)、菲咯啉(phen)为辅助配体,采用溶剂热法成功合成了3个过渡金属配合物:[Co_2(L_1)_2(bipy)(H_2O)_6]·bipy·H_2O (1)、[Cu(L_2)_2(bipy)_2]n(2)、[Ni_2(L_2)(phen)_2(H_2O)_4](3),并利用X射线单晶衍射法、红外光谱(IR)、荧光光谱(FL)和热重分析(TG/DTG)等测试手段对其进行了表征。单晶结构分析表明:配合物1、配合物2为P1空间群,配合物3为P2/n空间群;配合物1和配合物3为零维双核小分子结构,配合物2为二维层状结构。     

α,α′‐Diarylacenaphtho[1,2‐c]phosphole P‐Oxides: Divergent Synthesis and Application to Cathode Buffer Layers in Organic Photovoltaics

A divergent method for the synthesis of α,α′‐diarylacenaphtho[1,2‐c]phosphole P‐oxides has been established; α,α′‐dibromoacenaphtho[c]phosphole P‐oxide, which was prepared through a Ti^II‐mediated cyclization of 1,8‐bis(trimethylsilylethynyl)naphthalene, underwent a Stille coupling with three different kinds of aryltributylstannanes to afford the α,α′‐diarylacenaphtho[c]phosphole P‐oxides in moderate to good yields. X‐ray crystallographic analyses and UV/Vis absorption/fluorescence measurements have revealed that the degree of π‐conjugation, the packing motif, the electron‐accepting ability, and the thermal stability of the acenaphtho[c]phosphole π‐systems are finely tunable with the α‐aryl substituents. All the P?O and P?S derivatives exhibited high stability in their electrochemically reduced state. To use this class of arene‐fused phosphole π‐systems as n‐type semiconducting materials, we evaluated device performances of the bulk heterojunction organic photovoltaics (OPV) that consist of poly(3‐hexylthiophene), an indene‐C₇₀ bisadduct, and a cathode buffer layer. The insertion of the diarylacenaphtho[c]phosphole P‐oxides as the buffer layer was found to improve the power conversion efficiency of the polymer‐based OPV devices.