The Reaction of Ketenylidenetriphenylphosphorane (Ph3P˭C˭C˭O) with Acidic H‒E (E˭O,N) Bonds

Abstract

The reactivity of ketenylidenetriphenylphosphorane (1) with the protic reagents 2,4,6-trimethylphenol (7), 2,6-di-tert-butyl-4-methylphenol (8), and diphenylamine (9) has been explored. Three novel carbonyl-stabilized ylides have been synthesized and characterized. Crystal structures were obtained for Ph₃PCHC(O)O(C₆H₂Me₃) (11), Ph₃PCHC(O)O(C₆H₂t-Bu₂Me) (12), and Ph₃PCHC(O)NPh₂ (13), respectively. These products were then methylated in an attempt to develop a new route to low-valent carbon compounds. Crystals of [Ph₃PCH(CH₃)C(O)O(C₆H₂Me₃)]I (14) were isolated and characterized but this route did not prove to be synthetically useful, at least toward the goal of preparing low-valent carbon-centered materials. Finally, 1 was also reacted with the bulky tin reagent, bis[bis(trimethylsilyl)amido]tin(II), in the presence of 2,4,6-trimethylphenol. A complex mixture of products was obtained, from which crystals of an unusual chelated tin compound (15) were isolated and characterized using X-ray crystallography.     

Synthesis of Organophosphorus Compounds with ‒P˭P≡ and ‒P˭S˭ Units

Abstract

The lithium phosphide tetrahydrofurane complexes 1 react with phosphinic acid chlorides (2) to yield diphosphenes (4), possessing a tri- and a quinquevalent phosphorus atom; the diphosphane oxides 3 are regarded to be intermediate steps of the transformation.     

New Catalyst for Phosphonylation of C˭X Electrophiles

Abstract

Pyridinium perchlorate is found to be an efficient and recyclable catalyst for the reaction of trialkyl phosphites with various C?X electrophiles (aldehydes, ketones, ketophosphonates, imines, isocyanates, isothiocyanates, activated alkenes) to afford corresponding α-substituted phosphonates in good yields. The main advantages of the new catalyst is strong activity, accessibility, good yields of products, and gentle conditions of reaction.     

Microscale Preparation of Isotopically Enriched 37ClHC˭CHF

Abstract

Chlorination of 1‐bromo‐2‐fluoroethylene followed by reductive dehalogenation of the produced 1‐bromo‐1,2‐dichloro‐2‐fluoroethane selectively affords 1‐chloro‐2‐fluoroethylene. This process is suitable to produce ³⁷Cl isotopically enriched ClHC?CHF on a convenient scale (3.8 mmol).     

Phosphavinylidene-Carbenoids [P]˭C(Li)X (X ˭ Br,Cl, F): Structure and Dynamics

Abstract

The extraordinary reactivity of carbenoids towards electrophilic as well as nucleophilic reagents awards them for a central importance in organic chemistry. Their unusual bonding situation has been the subject of several theoretical studies'. Having shown in previous reports' that phosphoranyl carbenoids are significantly stabilized by incorporation of the carbenoid center in delocalized n-systems, we succeeded in isolating the first stable bromo. chloro and fluoro-lithio carbenoids 21-c.     

Quinolium Dichromate Adsorbed on Alumina: A Mild,Convenient, and Inexpensive Reagent for Cleavage of C˭N Under Nonaqueous Conditions

Oximes, hydrazones, and semicarbazones are converted to the corresponding carbonyl compounds using quinolium dichromate adsorbed on alumina (QDC/alumina) under nonaqueous conditions.     

β-Position Electronic Effects on the Singlet–Triplet Gaps of Divalent Five-Membered Rings XC4H3M (M˭C,Si, and Ge)

Abstract

Full geometry optimizations were carried out on the singlet and triplet states of β-substituted divalent five-membered rings XC₄H₃M (X? ?NH₂, ?OH, ?CH₃ ?H, ?CH₃, ?Br, ?Cl, ?F, ?CF₃, and ?NO₂; M?C, Si, and Ge) by the B3LYP method by using 6-311++G** basis set. The thermal energy gaps, ΔE_t–s; enthalpy gaps, ΔH_t–s; and Gibbs free energy gaps, ΔG_t–s, between the singlet (s) and triplet (t) states of the above structures were calculated by using the GAUSSIAN 03 program. The ΔG_t–s of XC₄H₃C was changed in the order: X? ?Cl > ?Br > ?CH₃ > ?H > ?CF₃ > ?F > ?NO₂ > ?OH > ?NH₂. The changes of ΔG_t–s for XC₄H₃Si and XC₄H₃Ge were in the order: X? ?NH₂ > OH > F > Cl > Br > CH₃ > H > CF₃ > NO₂. The geometrical parameters, including bond lengths (R), bond angles (A), dihedral angles (D), natural bonding orbital (NBO) charge at atoms, HOMO and LUMO, and dipole moments, were presented and discussed.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT      

Efficient Microscale Preparation of Isotopically Enriched 1‐[79Br]Bromo‐2‐Fluoroethylene, [79Br]BrHC˭CHF

Abstract

An efficient preparation of 1‐[⁷⁹Br]bromo‐2‐fluoroethylene, [⁷⁹Br]BrHC?CHF, was carried out by a three‐step procedure: (a) natural 1‐bromo‐2‐fluoroethylene, BrHC?CHF, was iodinated to 1‐fluoro‐2‐iodoethylene, FHC?CHI; (b) 1‐fluoro‐2‐iodoethylene was ⁷⁹Br₂‐brominated to 1,2‐di[⁷⁹Br]bromo‐1‐fluoro‐2‐iodoethane, [⁷⁹Br]BrFCHCH[⁷⁹Br]BrI; and (c) 1,2‐di[⁷⁹Br]bromo‐1‐fluoro‐2‐iodoethane was dehalogenated to 1‐[⁷⁹Br]bromo‐2‐fluoroethylene, [⁷⁹Br]BrHC?CHF. The yield of isolated product, on a 2‐mmol scale, was 62% with respect to ⁷⁹Br₂.     

SYNTHESIS,STRUCTURE AND REACTIVITY OF BIS(N-ARYL-IMINOPHOSPHORANYL)METHANES. X-RAY CRYSTAL STRUCTURES OF (4-CH3-C6H4-N˭PPh2)2CH2 AND (4-NO2-C6H4-N˭PPh2)2CH2

Abstract

The synthesis of novel bis(N-aryl-imino-phosphoranyl)methanes of the type CH₂(PR₂?N-Ar)₂ has been accomplished by reaction of methylene-bisphosphines with arylazides. These compounds have been fully characterized by ¹H, ³¹P and ¹³C NMR, IR spectroscopy, Field Desorption Mass Spectroscopy (? FDMS) and elemental analysis. Variable temperature NMR experiments and single crystal X-ray structure determinations of CH₂(PPh₂?N-C₆H₄-CH₃-4)₂ (la) and CH₂(PMe₂?N-C₆H₄-NO₂-4)₂ (1f) reveal that bis(N-aryl-imino-phosphorany1)methane occurs as tautomer 1. Crystals of la are orthorhombic, space group Pcab, with a = 26.602(2), b = 20.521(1), c = 11.8859(7) Å and V = 6488.5(7) ų (2 = 8, R = 0.045 and R_w = 0.066). The crystals of lf are monoclinic, space group C/2c, with a = 20.153(4), b = 5.952(1), c = 16.930(5) Å, β = 106.24(3)° and V = 1949.6(6) ų (Z = 4, molecular symmetry C₂, R_w = 0.051 and R, = 0.079). Both molecules consist of 2 iminophosphoranyl units bridged by a methylene group. The P?N bond distances of 1.568(2) and 1.566(2) Å for la and 1.580(4) Å for lf represent normal values for iminophosphoranyl compounds. The N-C bond lengths of 1.386(2) and 1.390(2) A (la) or 1.372(5) A for If indicate that some electron delocalisation over the N-aryl moiety takes place. In la the electron delocalisation takes place separately in each iminophosphoranyl entity, while in lf electron delocalisation occurs only in the N-aryl-NO₂ moiety.

Compound la is easily deprotonated using lithium-diisopropylamide or NaH and shows typical iminophosphoranyl chemistry, since with CO₂ an aza-Wittig reaction has been found and with HX (X?CI, Br) protonation of both imide nitrogen atoms has been observed.     

ÜBER PHOSPHAZO-VERBINDUNGEN AUS NITRILEN V.1 DIE REAKTIONEN VON ACETONITRIL,PHENYLACETONITRIL UND MALONSÄUREDINITRIL MIT [C13P˭N‒PC13]C1

Abstract

Acetonitrile reacts with P₂NC1₇ to give a mixture of the ring compounds CC1?CC1?N?PC1₂?N?PC1₂ (1) and CC?CC1?N?PC1₂?N?PC1₂ (2), phenyl acetonitrile to give C(C₆H₅)?CC1?N?PC1₂?N?PC1₂ (3). Malonic acid dinitrile and P₂NC1₇ in dichloroethane yield a mixture of the ring compound C(CN)?CC1?N?PC1₂?N?PC1₂ (4) and the chain compound PC1₃?N?PC1₂?N?CC1?CH?CN (5), while the latter compound is exclusively formed when the reaction is carried out in PC1₃. Preparation, nmr and mass spectra of the new compound are described and discussed.

Acetonitrile reacts with P₂NC1₇ zu einem Gemisch der ringförmigen Verbindungen CC1?CC1?N?PC1₂?N?PC1₂ (1) und CC?CC1?N?PC1₂?N?PC1₂ (2), Phenylacetonitril zu C(C₆H₅)?CC1?N?PC1₂?N?PC1₂ (3). Aus Malonsäuredinitril und P₂NC1₇ entsteht in Dichloräthan ein Gemisch des Heterocyclus C(CN)?CC1?N?PC1₂?N?PC1₂ (4) und der kettenförmigen Verbindung PC1₃?N?PC1₂?N-CC1?CH?CN (5), wöhrend in PC1₃ als Reaktionsmedium ausschlieβlich die Verbindung 5 gebildet wird. Darstellung, NMR- und Massenspektren der neuen Verbindungen sind beschrieben und diskutiert.     

SYNTHESIS,ELECTROCHEMICAL CHARACTERIZATION AND POTENTIOMETRIC TITRATION of trans-[RuCl2(L)4] COMPLEXES (L ˭ PYRIDINE DERIVED LIGANDS: 3-PYRIDINECARBOXYLIC ACID AND 4-PYRIDINECARBOXYLIC ACID)

Abstract

In this work we report the synthesis, spectroscopic characterization, potentiometric titration and electrochemical studies performed on trans-[RuCl₂(nic)₄] (1) and trans-[RuCl₂(i-nic)₄] (II) complexes, where nic = 3-pyridinecarboxylic acid and i-nic = 4-pyridinecarboxylic acid. The complexes were synthesized using a ruthenium blue solution as a precursor in the synthetic route, and characterized by electronic spectroscopy, vibrational FT-IR spectroscopy, and ¹H and ¹³C NMR. The results indicated a trans geometry. Cyclic voltammetry performed in water/ acetone (1:1) solution revealed a quasi-reversible process centered on the Ru(II) species and a dependence of the redox potential, E _1/2, on the pH. The electronic spectra showed that the MLCT bands were also affected by the pH, undergoing a hypsochromic shift (blue shift) as the pH increased. The spectroelectrochemical analysis indicated that the bands in the visible region progressively faded as new UV bands emerged during the oxidation process. The equilibrium constants for trans-[RuCl₂(nic)₄] and trans-[RuCl₂(i-nic)₄] were determined by potentiometric titration, indicating that protonic species dominated at pH values lower than 2.6, whereas non-protonic species dominated at pH values higher than 5.0.     

Efficient Selective Formation of C‐C Single Bonds and C˭C Double Bonds by NBS‐Promoted Oxidative Coupling of β‐Keto Esters

Abstract

A new application of NBS, which results in the oxidative coupling of β‐keto esters to selectively form C‐C single and C?C double bonds, can be controlled by the amount of NBS and t‐BuOK employed. This methodology adds a new entry to C‐C single and C?C double‐bond formation between active methylene groups under mild conditions with high selectivity.     

SYNTHESIS AND STRUCTURAL CHARACTERIZATIONS OF {μ3-H(Ph)C˭C} FeCo2(CO)7dppfe (dppfe ˭ 1,1′-BIS(DIPHENYLPHOSPHINO)FERROCENE): INTRAMOLECULAR π-πINTERACTION BETWEEN THE APICAL PHENYL GROUP OF THE CLUSTER AND A PHENYL GROUP IN DPPFE

Abstract

Thermal reaction of {μ₃-H(Ph)C?C} FeCo₂(CO)₉ (1) with dppfe in benzene affords dark green {μ₃-H(Ph)C?C} FeCo₂(CO)₇dppfe (2). The molecular structures of 1 and 2 have been determined by single crystal x-ray analysis; dppfe replaces two equatorial carbonyls from two Co(CO)₃ groups. Thus, dppfe approaches the apical phenyl group. This unusual conformation has been analyzed by computer visualization of the π electrons of the apical phenyl group and one of the phenyl groups in dppfe to indicate an intramolecular π π interaction between these two phenyl groups. Atomic charge analysis by Extended Hückel (E. H.) calculation suggests why dppfe coordinates to Co atoms preferentially. Cyclic voltammetric behavior for these compounds is interpreted in terms of HOMO and LUMO, which have also been analyzed by E. H. calculations.     

REACTIONS OF [η5−RC5H4 (CO)2Mo]2 (Mo≡Mo) WITH (μ-PhSe)2Fe2 (CO)6. SYNTHESIS AND CHARACTERIZATION OF SELENOLATO-BRIDGED TRANSITION METAL COMPLEXES [η5−RC5H4Mo (CO) (μ-SePh)]2 (R ˭ MeCO,MeO2C) AND η5−RC5H4MoFe2 (CO)4 (μ3-Se) [μ,η1: η2−C(0)Ph] (μ-SePh)2 (R ˭ H,MeCO, EtO2C)

Abstract

Mo≡Mo triply bonded dimers [η⁵?RC₅H₄ —react with (μ,-PhSe)₂Fe₂ (CO)₆ in boiling xylene to give selenolato-bridged bimetallic complexes [η⁵?RC5H₄Mo(CO) (μ-SePh)]₂ (R ? MeCO, MeO₂C). However, irradiation of a benzene solution of —(R ? H, MeCO, EtO₂C) and (μ-PhSe)₂Fe₂ (CO)₆ with a 400W high pressure mercury lamp gave rise to selenolato-bridged trimetallic clusters η⁵?RC₅H₄MoFe₂(CO)₂ (μ₃-Se) [μ,η:η²?C (O) Ph] (μ-SePh)₂ (R ? H, MeCO, EtO₂C). All products were characterized by elemental analysis and spectroscopic methods, as well as by an X-ray diffraction analysis of the product η⁵?MeCOC₅H₄MoFe₂(CO)₄ (μ-Se)[μ;η¹:η²?C(O)Ph](μ-SePh)₂.     

SYNTHESIS AND CRYSTAL STRUCTURE OF 5, 10, 15, 20, 22, 24-HEXAHYDRO-5, 5, 10, 10, 15, 15, 20, 20-OCTAMETHYL-PORPHINE

<正> The title com pound (HHOMP) has been synthesized with the pho-toinduced condensation of acetone and pyrrole in the presence of iodoaromatic hydrocarbons, and its molecular and crystal structures have been determined by X-ray analysis. C28H36N4, Mr = 428. 63, triclinic; space group P1; a =10. 165(3), b = 10. 185(2), c=13. 012(3)(?); α=85. 41(2), β=67. 84(2), γ= 89. 75(2)°; V = 1243 (?)3; Z = 2; D = 1. 145g. cm-3; μ= 0. 635cm-1; F (000) = 464. Although the HHOMP molecule twists, it is found that the four nitrogen atoms are still in a plane.     

在小硅化物SiX^m4（X=H,He,Li,Be,O,F,Ne,Na,Mg,S,Cl,Ar;m=0,…

用从头算方法，在ＨＦ／ＳＴＯ－３Ｇ、ＨＦ／３－２１Ｇ和ＨＦ／６－３１Ｇ水平上研究了小硅化物ＳｉＸ＾ｍ４的成键倾向性。计算结果表明，所研究的分子势能曲线均有稳定的极小值（ＳｉＬｉ４除外）。与已知的稳定分子ＳｉＨ１、ＳｉＦ４和ＳｉＣｌ４比较，含惰性元素的未知分子ＳｉＨｅ＾４＋４、ＳｉＮｅ＾４＋４和ＳｉＡｒ＾４＋４比含碱金属和碱土金属的未知分子ＳｉＬＩ４、ＳｉＮａ４、ＳｉＢｅ＾４＋４和ＳｉＭｇ＾４＋４有     

Theoretical Study on the Structure and Stability of Si5X （X = Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl） Clusters

1 INTRODUCTION In the later 60s of last century, silicon substituted for germanium to present as mainstream in semicon- ductor. The semi-conductive devices made by silicon have many advantages, for example, refractory pro- perty, high radioresistance, simple and stable process- ing technic, high machinability and low cost. So it was widely used to manufacture large power appara- tuses, for instance, digit and linear integrated circuit, large scale integrated circuit (LSI), etc. Thus, th…