Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Calculated Properties of Triphospha[1.1.1]propellane (1994)
    s.l. : American Chemical Society
    Inorganic chemistry 33 (1994), S. 1153-1157 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic00084a030
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Reaction of Phosphaethene with Hydrogen Isocyanide: [2+1] versus [2+2] Cycloaddition (1995)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 117 (1995), S. 7535-7543 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00133a027
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The thionitroxyl free radical (H2NS) and its ionic counterparts (H2NS+ and H2NS−): A theoretical and experimental study (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 4885-4892 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An experimental and theoretical characterization has been carried out for the thionitroxyl radical (H2NS) and its ionic counterparts (H2NS)+ and (H2NS)−. Experimentally, (H2NS)+ and (H2NS) have been detected by a combination of collisional activation and neutralization-reionization mass spectrometry. Thiourea has been used as a precursor. Theoretically, the neutral and ionic potential energy surfaces have been explored using (PU)MP4/6-311++G(3df,2p) energies based on (U)MP2/6-311++(d,p) geometries. Predictions for some spectroscopic and thermochemical properties have been made on the basis of molecular orbital calculations and empirical corrections. The rearrangements leading to the (HNSH) and (NSH2) isomeric species and the loss of hydrogen or other fragmentations have also been examined. The (HNSH) and (NSH2) species are less stable than their respective thionitroxyl isomers in all states considered. For the (H2NS)+ cation, an H loss constitutes the lowest energy fragmentation followed by an H2 elimination giving NS+ and a cleavage of the N–S bond. The thermochemical data are predicted as follows: ΔH0f,0 (H2NS)=31.2±3 kcal/mol, IEa(H2NS)=88.±0.2 eV, EAa(H2NS)=1.4±0.2 eV, PA(H2NS−)=357.5±3 kcal/mol as compared with the experimental value of 356.8±3 kcal/mol, ΔH0f,0(HNS)=52.6±3 kcal/mol and ΔH0f,0(H2NSH)=13.4±3 kcal/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467410
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Theoretical Study of the Thermal Decomposition of Acetic Acid: Decarboxylation Versus Dehydration (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 11883-11888 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100031a015
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Properties of phosphorus compounds by density functional theory: CH3P species as a test case (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 1922-1932 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A comparison of different density functional theory (DFT) and molecular orbital (MO) methods for calculating molecular and energetic properties of low-coordinated phosphorus compounds is reported. While DFT methods include both Becke–Lee–Yang–Parr (BLYP and B3LYP) nonlocal functionals, MO methods involve second-order perturbation theory (MP2), quadratic configuration interaction [QCISD(T)], and coupled-cluster theory [CCSD(T)], in conjunction with the 6-31G(d,p), 6-311++G(3df,2p), and 6-311++G(3df,3pd) basis sets. Properties examined include geometrical parameters of the different CH3P equilibrium structures (phosphaethene, phosphinocarbene, methylphosphinidene, and a phosphacarbyne) and relevant transition structures for isomerisations and rearrangements in both the lowest-lying singlet and triplet states, vibrational wave numbers, relative energies, barrier heights, and singlet–triplet energy gaps. In addition, the heat of formation, ionization energy, and proton affinity of phosphaethene are also evaluated. Overall, the B3LYP method, when employed with a large basis set, yields energetic results comparable to the CCSD(T) results. Nevertheless, both DFT methods fail to predict the behavior of the addition/elimination reactions of the hydrogen atom in the triplet state. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472062
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A Density Functional Study of the Dimerization of Phosphaalkynes in the Presence of Transition Metal Fragments (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1281-1289 
    Details
    ISSN: 1434-1948
    Keywords: Phosphaalkynes ; Dimerization mechanism ; Diphosphacyclobutenes ; Density functional theory ; Ab initio calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dimerization of phosphaalkynes (R-C≡P, R = H, Me, tBu) without and with the presence of transition metal fragments, including CpCo (Cp = cyclopentadienyl) and COT-Ti (COT = cyclooctatetraene), has been probed using density functional theory calculations (B3LYP with different basis sets). MP2 and CCSD(T) calculations were also performed for the [H2C2P2] systems. In an attempt to address the exciting controversy and uncertainty about phosphaalkyne dimerization, a number of dimer formation mechanisms proposed in the literature have been examined. Some new and plausible intermediates have also been identified.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Calculated Properties and Ring-Chain Rearrangements of Triphosphirane (P3H3) (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 103-112 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Ionization potentials ; Phosphorus ; Heterocycles ; Small ring systems ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio quantum chemical calculations have been used to explore the P3H3 potential energy surface focussing on the ring-chain rearrangements of the three-membered ring in (PH)3 (1), the parent triphosphirane. Relative energies between stationary points were estimated using the QCISD(T)/6-311G(d,p) method based on MP2/6-31G(d,p) geometries and corrected for zero-point contributions. Ring strain, proton affinities, ionization and excitation energies and heats of formation have been evaluated using larger basis sets, e.g. 6-311++G(3df,2p). The cyclic trans-triphosphirane (1a) is the most stable P3H3 isomer and lies about 40 kJ/mol below the open-chain phosphanyldi-phosphene (H2P-P=PH). The decrease of ring strain in three-membered rings when CH2 is replaced by PH is confirmed. Triphosphirane 1a is a virtually strain-free ring and even gains some stabilization relative to three separate P-P single bonds. The reduced ring strain also helps diminish the phosphorus inversion barrier to 224 kJ/mol compared to the monocyclic isomers of (CH2)(PH)2 and (CH2)2(PH). Compound 1a follows a pure ring-opening or a 1,2-hydrogen shift rather than a combined motion pathway, in fundamental contrast with corresponding processes of diphosphirane and phosphirane. This is due to the existence of an open-chain P3H3 phosphorane intermediate stabilized by allylic conjugation. The pericyclic ring-opening of 1a is the most favored process but the energy barrier in the gas phase is about 180 kJ/mol high. Electron density is largely delocalized within the three-membered P3 ring not only in the C3v-symmetric 1b (all-cis) but also in 1a (Cs). The proton affinity of 1a is similar to that of PH3. The proton affinities decrease with n in cyclo-(CH3)3 -n(PH)n and their values were obtained: PA(1a) = 777 ±10, PA(diphosphirane) = 799 ±10 and PA(phosphirane) = 802 ±10 kJ/mol. Heats of formation are evaluated as follows (ΔH°f0 at 0 K in kJ/mol): 1a, 70 ±10; cyclo-(PH)2(PH2)+ (protonated 1a), 821 ±10; diphosphirane, 85 ±10; cyclo-(CH2)(PH)(PH2)+ (protonated diphosphirane), 814 ±10; phosphirane, 86 ±10; and protonated phosphirane, 812 ±10 kJ/mol. All P rings remain cyclic following ionization to the radical cations. Adiabatic ionization energies (IEa) are estimated as: 1a and diphosphirane, 9.3 ±0.3 eV and phosphirane 9.5 ±0.3 eV. The first UV absorption band shifts toward the longer wavelength region on going from phosphirane to 1a. The GIAO/B3LYP computed magnetic shieldings for 1a and related molecules reveal a clear relationship between the narrow bond angles in the rings and their unusually strong magnetic shielding. The similarity of the predicted 31P-NMR signals in 1a and its heteroanalog diphosphirane, (CH2)(PH)2, can be rationalized in terms of a compensation of the carbon-substituent effect (downfield shift) and the bond-bending effect imposed by the ring (upfield shift).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    Phosphinidene Transition Metal Complexes: A Combined Ab Initio MO-DFT Study of Cr(CO)5-PR (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 107-115 
    Details
    ISSN: 1434-1948
    Keywords: Ab initio calculations ; Density functional calculations ; Phosphinidene ; Carbonyl complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO and DFT calculations have been performed on phosphinidene complexes of the type Cr(CO)5-PR, with R = H, CH3, SiH3, NH2, PH2, OH, and SH. The formation of the Cr-P bond essentially arises from a ligand-to-metal charge transfer. While a significant π backdonation is also observed for the Cr(CO)5-PH, Cr(CO)5-PCH3, and Cr(CO)5-PSiH3 complexes, this is less the case for Cr(CO)5-POH, Cr(CO)5-PSH, and Cr(CO)5-PNH2, and the backbonding almost disappears for Cr(CO)5-PPH2. In both the lowest lying singlet and triplet states, all complexes exhibit a staggered conformation. CASSCF/CASPT2 calculations performed with the ANO basis sets indicate a closed-shell singlet ground state along the whole series. The binding energy between Cr(CO)5 and PR ranges from 216 kJ/mol for Cr(CO)5-PNH2 to 127 kJ/mol for Cr(CO)5-PSiH3 (B3LYP values). In general, the B3LYP-DFT scheme yields reasonable qualitative and quantitative results when compared with CASPT2(12/12).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    Electronic Resource
    Electronic Resource
    A Theoretical Investigation of Cycloadditions of Hydrogen Isocyanide to CH2=X and PH=X Dipolarophiles (X = CH2, NH, O, SiH2, PH, S)We dedicate this paper to the memory of our friend and colleague, Prof. Dr. Gerrit L'Abbé, who untimely passed away on August 27, 1996. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 69-76 
    Details
    ISSN: 0009-2940
    Keywords: [2 + 1] Cycloadditions ; Hydrogen cyanide ; Phosphorus dipolarophiles ; Three-membered rings ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We performed a systematic investigation of [2 + 1] cycloadditions of HN≡C to dipolarophiles of the type CH2=X and PH=X with X=CH2, NH, O, SiH2, PH, and S, as well as HN=NH and H2Si=SiH2. Ab initio MO calculations at the QCISD(T)/6-311G(d,p)/MP2/6-31G(d,p)+ZPE level were applied to construct the minimum-energy reaction pathways. Calculated results concerning the regiochemistry of the approaches and the stereochemistry of the product formation were analyzed in relation with established concepts such as frontier orbital, net charge distribution and stereoelectronic effect. For some systems, up to four distinct transition structures for cycloaddition were found. In general, there is a certain similarity between the behavior of both C and P series of dipolarophiles. The characteristics of the transition structures can be, in most cases, recovered by using qualitative concepts. The [2 + 1] cycloadditions are highly regioselective and stereospecific. Silicon-containing dipolarophiles are particularly attractive as they exhibit very small energy barriers to addition to isocyanides.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300111
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Remarkable Effect of Fluorine and Chlorine Atoms on the Stability of 1H-Phosphirene (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 923-927 
    Details
    ISSN: 0009-2940
    Keywords: 1H-Phosphirenes ; 2H-Phosphirenes ; Calculations, ab initio ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO calculations at the MP4/6-31G** level show that both fluorine and chlorine atoms exert a strong stabilizing effect on the three-membered ring 1H-phosphirene relative to its isomers. While unsubstituted 1H-phosphirene (12H) is the least stable C2H3P isomer, 1-fluoro-1H-phosphirene (12F) is calculated to be the global minimum of the C2H2FP potential energy surface; 1-chloro-1H-phosphirene (12Cl) is the third most stable of the six C2H2ClP isomers calculated. The remarkable stability of 12F is attributable to the particular strength of the P - F bond.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250425
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...