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51. Front Cover: Bis‐[3]Ferrocenophanes with Central >E−E’< Bonds (E, E’=P, SiH): Preparation, Properties, and Thermal Activation (ChemistryOpen 10/2019)

Author

Isenberg, Stefan, primary, Weller, Stefan, additional, Kargin, Denis, additional, Valić, Srećko, additional, Schwederski, Brigitte, additional, Kelemen, Zsolt, additional, Bruhn, Clemens, additional, Krekić, Kristijan, additional, Maurer, Martin, additional, Feil, Christoph M., additional, Nieger, Martin, additional, Gudat, Dietrich, additional, Nyulászi, László, additional, and Pietschnig, Rudolf, additional

Published
2019
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52. Lithium phosphoranylidene carbenoids Mes*-P(=E)=C(X)Li(THF)3 (E = NMes*, C(SiMe3)2; X = Br, Cl, F): synthesis and structural investigations in solution and solid state

Author

Baumgartner, Thomas, Gudat, Dietrich, Nieger, Martin, Niecke, Edgar, and Schiffer, Thomas J.

Subjects
X-ray diffractometer -- Usage, Nuclear magnetic resonance spectroscopy -- Usage, Carbon compounds -- Research, Chemistry
Abstract

Research was conducted to examine the synthesis of phosphoranylidene carbenoids Mes*-P(=E)=C(X)Li(THF)3 (E = NMes*, C(SiMe3)2; X = Br, Cl, F) and to characterize their molecular structures using low-temperature X-ray diffractometry and multinuclear NMR studies. Results confirm the presence of moomeric molecules with THF-solvated metal atoms in both solution and solid state. NMR studies demonstrate that the dynamic exchange between the two components in solution can be directly monitored in 2D 6Li, 31P shift correlations.

Published
1999

53. Spectroscopic and structural characterization of a phosphavinylidene carbenoid, Mes*-P=C(Cl){Li(DME)2}: stabilization of a carbenanionic center by a cisoid lone pair interaction

Author

Niecke, Edgar, Nieger, Martin, Schmidt, Olaf, Gudat, Dietrich, and Schoeller, Wolfgang W.

Subjects
Complex compounds -- Research, Chemical structure -- Research, Nuclear magnetic resonance spectroscopy -- Usage, X-ray diffractometer -- Usage, Chemistry
Abstract

The phosphavinylidene carbenoid DME-solvate (Z)-Mes*-P=C(Cl){Li(DME)2} or the corresponding THF-solvate was distinguished by nuclear magnetic resonance spectroscopy and single-crystal X-ray diffractometry. Carbenoids were believed to be possible building blocks in organic chemistry and exhibit unique bonding capacity. It was observed that the carbenoid complex was a closely bound ion pair with its carbenic core acting mainly as a cryptocarbanion.

Published
1999

55. Cationic Diiodo-Phosphoranides through Oxidative I-2 Addition to Tricyclic Phosphamethine Cyanines

Author

Cicac-Hudi, Mario, Schlindwein, Simon H., Feil, Christoph M., Nieger, Martin, Gudat, Dietrich, and Department of Chemistry

Subjects
Charge transfer, Phosphamethine cyanines, Halogenation, Nitrogen heterocycles, 116 Chemical sciences, HETEROCYCLIC CARBENE ADDUCTS, Phosphorus, BOND, PHOSPHORUS(I) CATIONS
Abstract

Reaction of methylene- and ethylene-bridged bis-imidazolium salts with white phosphorus in the presence of KOtBu furnished moderate yields of tricyclic bis-imidazolio-phosphanide halides. Further oxidation of the products with one equivalent of I-2 gave bis-imidazolio-diiodophosphoranide iodides. All newly prepared compounds were characterized by analytical and spectroscopic data and single-crystal XRD studies. DFT calculations provide evidence for substantial stabilization of cyclic bis-imidazolio-phosphanide cations by pi-conjugation effects and suggest describing the bis-imidazolio-diiodophosphoranide cations as charge-transfer complexes of dicationic iodophosphines with iodide.

Published
2018

56. Reactions of bis(triphenylphosphonio)isophosphindolide salts with mercury(II) compounds: coordination induced addition and oxidation reactions and synthesis of a monomeric 1:1 complex of the type [R2(R'O)P]HgBr2

Author

Gudat, Dietrich, Nieger, Martin, and Schrott, Martin

Subjects
Phosphorus compounds -- Analysis, Mercury compounds -- Analysis, Complex compounds -- Analysis, Chemistry
Abstract

The reactivity of the bis(triphenylphosphonio)isophosphindolide triflate was analyzed during the reaction of the bis(phosphonio)isophosphindolide cation with Hg2+. A phosphinito complex was formed by the reaction of the bis(phosphonio)isophosphindolide cation with HgCl2 and H2O or MeOH. The conversion of bis(triphenylphosphonio)isophosphindolide to phosphonium ions also involved 1,1-oxidative additions at the two coordinate phosphorus which was similar to isoelectronic compounds.

Published
1997

58. Steric Control in Reactions of N-Heterocyclic Phosphorus Electrophiles with Pentacarbonyl Manganate(-I)

Author

Papendick, Marius, Feil, Christoph M., Nieger, Martin, Gudat, Dietrich, and Department of Chemistry

Subjects
Steric effects, IONS, NHC, Reaction mechanisms, 116 Chemical sciences, MULTIPLE BOND, N-heterocyclic phosphenium complex, METAL-COMPLEXES, LIGANDS, CARBENES, PHOSPHENIUM COMPLEX, P ligands, Ligand design
Abstract

Metathesis of Na[Mn(CO)(5)] with N-tBu and N-Mes substituted, electrophilic N-heterocyclic phosphane derivatives afforded in the first case an ionic N-heterocyclic phosphenium (NHP) metalate and in the second case a covalent phosphenium complex. The products were characterized by analytical and spectroscopic data and the NHP complex as well by a single-crystal X-ray diffraction study. A DFT study allows relating the different outcome of the reactions studied with the energetics of the decarbonylation of the appropriate NHP metalates. Closer evaluation reveals steric factors as the key to explaining the observed behavior, and indicates that their impact displays close parallels to NHC chemistry.

Published
2018

68. Chirality Transfer of Stereogenic Boron Centers Enabled by a SN2-Type Mechanism

Author

Stöckl, Yannick, Gugeler, Katrin, Holzwarth, Celine M., Frey, Wolfgang, Wegner, Sascha, Claasen, Birgit, Zens, Anna, Gudat, Dietrich, Sindlinger, Christian P., Kästner, Johannes, and Laschat, Sabine

Abstract

Enantioenriched boron chelates show promising synthetic and luminescent properties; however, the challenging synthesis makes these compounds scarce. In our earlier work, we established a chirality transfer from boron O,N-chelates toward enantioenriched C,N-chelates. This methodology proved to be quite robust, in terms of yields and selectivity. However, unexpected steric effects on stereocontrol prompted a deeper investigation of the chirality transfer. In order to gain a holistic understanding of this process, we studied the structure of the O,N- and C,N-chelates as well as the stability of the dative B–N bonds. Furthermore, the proposed ate-complex as a reaction intermediate could be characterized using heteronuclear (2D) NMR spectroscopy. For this ate-complex, a tridentate O,N,N-chelate effect of the borate anion with the Li-cation was observed. Additional experiments indicated that the borate formation governs the stereoselectivity of chirality transfer. For a successful chirality transfer, an unprecedented SN2-type breaking of the dative B–N bond with an organometallic nucleophile was identified by DFT calculations as the most likely reaction path. For other cases, decreased or inverse enantioselectivity was rationalized by a solvent-assisted pathway.

Published
2024
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69. N-Heterocyclic Phosphenium Complexes of Vanadium

Author

Papendick, Marius, Birchall, Nicholas, Nieger, Martin, and Gudat, Dietrich

Abstract

Isolable N-heterocyclic phosphenium (NHP) complexes of vanadium were prepared by cophotolysis of Na[V(CO)6] and 2-bromo-1,3,2-diazaphospholenes. Single-crystal XRD studies revealed that the complexes exhibit trigonal planar coordination at phosphorus and short P–V distances indicative of phosphorus–metal double bonding. An exemplary reaction with Li[BEt3H] proceeded via hydride transfer to the phosphorus atom to yield an anionic secondary phosphine complex, which resisted protonation by [Et3NH]Cl and differed in this aspect from a previously reported manganese-based analogue. DFT calculations were carried out to analyze metal–ligand interactions in the NHP vanadium complexes and to rationalize the different behavior of the vanadium- and manganese-based species in H–/H+-transfer reactions.

Published
2024
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76. Tris(pyrazolyl)phosphines with copper(i): from monomers to polymers

Author

Tazelaar, Cornelis G J, Nicolas, Emmanuel, van Dijk, Tom, Broere, Daniël L J, Cardol, Mitchel, Lutz, Martin, Gudat, Dietrich, Slootweg, J Chris, Lammertsma, Koop, Sub Crystal and Structural Chemistry, and Crystal and Structural Chemistry

Abstract

The parent tris(pyrazolyl)phosphine and its 3,5-Me2, 3-Ph, and 3-t-Bu derivatives have been prepared by a simple procedure and show modest Lewis basicity of the phosphorus apex as was established by the magnitude of the (1)JP,Se coupling constant of the phosphine selenides. Because of the chelating properties of both the N- and P-sites, neutral phosphorus-centered scorpion ligands allow coordination modes that are unavailable to the abundantly used anionic tris(pyrazolyl)borate scorpionates as we established for Cu(i)-complexation. The substituted P-scorpion ligands only allow for N-coordination, as the P-apex is presumably less accessible. Two X-ray crystal structures were obtained for the Cu-complex of tris(3,5-dimethylpyrazolyl)-phosphine with acetonitrile and triphenylphosphine in the fourth coordination site. The parent P-scorpion ligand can chelate with both its pyrazolyl groups and its P-apex with the product depending on the ratio in which it is mixed with the Cu(i) complex. Reacting two equivalents of the ligand with [Cu(MeCN)4][PF6] resulted in a complex in which Cu is coordinated to the three pyrazolyl groups of one ligand and to the P-apex of the other ligand as confirmed by an X-ray crystal structure determination and a DFT computational analysis. Reacting the ligand and the Cu(i) complex in an equimolar ratio resulted in a remarkable one-dimensional P-scorpion coordination polymer for which a single crystal X-ray structure could be determined. A detailed analysis of the structural features is presented.

Published
2016

77. Diphosphines with strongly polarized P-P bonds: hybrids between covalent molecules and donor-acceptor adducts with flexible molecular structures

Author

Burck, Sebastian, Gotz, Kathrin, Kaupp, Martin, Nieger, Martin, Weber, Johannes, Gunne, Jorn Schmedt auf der, and Gudat, Dietrich

Subjects
Electron donor-acceptor complexes -- Analysis, Nuclear magnetic resonance spectroscopy -- Usage, X-rays -- Diffraction, X-rays -- Usage, Chemistry
Abstract

The single-crystal X-ray diffraction and solution and solid-state [super 31]P NMR spectroscopy were employed to prepare and characterize a series of P-phospholyl-substituted N-heterocyclic phosphines. The experimental observations and population analysis of computed electron densities classified the P-P bonds in the molecules under study as 'dative' rather than 'normal' covalent bonds and addressed the compounds as hybrids between covalent diphosphines and phosphenium-phospholide contact ion pairs.

Published
2009

78. Structural alternatives for the formation of halogenophosphine-phosphenium complexes

Author

Burck, Sebastian and Gudat, Dietrich

Subjects
Nuclear magnetic resonance -- Usage, Density functionals -- Usage, Chemistry
Abstract

NMR studies of diamino phosphenium ions and p-chlorophosphines reactions shows they react via chloride scrambling, and not by the formation of P-P bonded phosphenium-phosphine complexes. A computational study in the gas phase show the formation of halide-bridge adducts is preferred over the energetically less favorable P-P bonded structures.

Published
2008

87. Phosphines with N‐Heterocyclic Boryl‐Substituents: Ligands for Coordination Chemistry and Catalysis.

Author

Kaaz, Manuel, Locke, Ralf J. C., Merz, Luisa, Benedikter, Mathis, König, Simon, Bender, Johannes, Schlindwein, Simon H., Nieger, Martin, and Gudat, Dietrich

Subjects
COORDINATE covalent bond, CATALYSIS, PHOSPHINES, LIGANDS (Chemistry), TRANSITION metals
Abstract

Boryl‐substituted phosphines NHB–P(R)Ph (R = H, Ph, NHB = N‐heterocyclic boryl substituent) react with Fe2(CO)9 to give isolable Fe(CO)4 complexes, two of which were characterized by single‐crystal XRD studies. The electronic and steric properties for a series of the boryl phosphines were further assessed by evaluation of TEPs for in‐situ formed complexes [RhCl(NHB–PR1R2)(CO)2] (R1, R2 = H, Ph, Me, NMe2), and calculations of buried volumes for Fe(CO)4 complexes. The results imply that the NHB‐phosphines exhibit due to their conformational flexibility some variability in their steric bulk, and that some specimens may exhibit similar electron releasing power and steric demand as tBu3P. Studies of the amination of bromobenzene with 2,6‐diisopropylaniline confirmed that these properties can be exploited to promote Pd‐catalyzed C–N cross coupling reactions, and that formal replacement of a phenyl by a NHB substituent in the auxiliary phosphine has a beneficial effect on catalyst performance. Phosphines with an N‐heterocyclic boryl substituent at phosphorus behave as strongly electron releasing ligands that may impart despite their conformational flexibility sizeable steric shielding to a transition metal atom. This makes them suitable candidates for application as ligands in cross‐coupling chemistry. [ABSTRACT FROM AUTHOR]

Published
2019
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99. Multinuclear magnetic resonance study of sterically crowded stannylphosphines and stannylamines : stereochemical influences on chemical shielding and spin-spin couplings

Author

Dörr, Armin, Gudat, Dietrich, Hänssgen, Dieter, Hens, Heribert, and Stahlhut, Edith

Subjects
NMR-Spektroskopie , Stannylphosphine , Stannylamine
Abstract

Multinuclear (1H, 15N, 29Si, 31P, 119Sn) NMR data of sterically crowded acyclic stannylphosphines tBu3SnPHY (Y = H, SnMe3, SntBu3, SiMe3; 1-3, 10), (tBu2RSn)2PH (R = Me, Cl; 4, 5), tBu3SnPY2 (Y = SnMe3, SiMe3; 6, 11), PH(SntBu2PHSntBu3)2 (7), SntBu2(PY2)2 (Y = H, SiMe3, PHSntBu3; 8, 9, 12), cyclic stannylphosphines (tBu2SnPY)n (n = 2, Y = H, C3H6Cl, tBu, SnMe3; 13-16; n = 3, Y = H; 18), (Me2SnPSntBu3)2 (17), and stannylamines tBu3SnNHY (Y = H, SnMe3, SntBu3; 19-21) were obtained by various 1D- and 2D-techniques. 31P- and 15N-shieldings may be explained qualitatively in terms of two counteracting influences, viz electronegativity differences and steric requirements of the substituents. In a similar manner, the trends in one-bond coupling 1KSnP and 1KSnM may be rationalized using a simple model based on the deformation of bond angles by sterically demanding substituents. The signs of long-range couplings 2KSnPH and 1KPSnCCH could be determined, which may be useful for future structural studies. Temperature-dependent effects in the spectra of 13, 18 allow conclusions about the conformational dynamics of the molecules.

Published
2012
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100. Olefin-, Carben- und Nitren-Analoge im Phosphorsystem

Author

Niecke, Edgar, Böske, Jürgen, Gudat, Dietrich, Güth, W., Lysek, Manfred, and Symalla, Erhard

Subjects
Iminophosphane , Methylenphosphane , Phosphoalkene
Abstract

Mit der Entdeckung der resonanzstabilisierten Phosphamethincyanine durch Dimroth und Hoffmann /1/ und Phosohabenzole durch Märkl /2/ Mitte der sechziger Jahre hat eine stürmische Entwicklung auf dem Gebiet der Phosphorverbindungen mit Phosphor-Element-(p-p)-π-Bindungen eingesetzt. Im Verlauf dieser Aktivitäten gelang 1973 in unserem Arbeitskreis /3/ und 1976 Becker /4/ mit der Synthese der ersten Imino- und Methylenphosphane der Zugang zu isolierbaren Systemen mit Phosphor-Stickstoff- und Phosphor-Kohlenstoff-Doppelbindungen. Einen weiteren Höhepunkt dieser Forschungen stellt die Entdeckung des Diphosphensystems durch Yoshifuji und Mltarbeiter 1981 dar /5/, mit der erstmals die Verifizierung einer (3p-3p)-π-Bindung beim Phosphor gelang. Der folgende Bericht gibt eine Zusammenfassung von eigenen Arbeiten über die drei letztgenannten Verbindungssysteme, wobei der Vergleich der Chemie dieser Verbindungen mit bekannten Systemen der organischen Chemie eine zentrale Rolle spielt.

Published
2012
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