With the death of Reinhard Schmutzler on July 26, 2014, inorganic chemistry worldwide has suffered a significant loss of one of the notable characters of the latter half of the 20th century. For ov...

Me3SiCP may be prepared by dehydrochlorination of Me3SiCH2PCl2 at room temperature in aromatic solvents using DABCO in the presence of AgOTf. Reaction of Me3SiCP with a selection of s-block metals, s-block metal salts and ytterbium effects conversion to a mixture of di- and triphospholide anions. This mixture of anions was subsequently reacted with FeCl2 to yield a mixture of tetra-, penta- and hexaphosphaferrocenes.

New insight into the mechanism of the ambient temperature PCl5-initiated living cationic chain growth polycondensation of the N-silylphosphoranimine Cl3P=NSiMe3 (1) to give poly(dichlorophosphazene), [N=PCl2]n, has been provided by studies of model compound chemistry. Investigations of the reactivity of Cl- salts of the proposed cationic intermediates [Cl3P=N=PCl3]+ ([2]+) and [Cl3P=N-PCl2=N=PCl3]+ ([6]+) toward Ph3P=NSiMe3 (3a) provided evidence that under the usual polymerization conditions that involve a high monomer to initiator ratio, propagation occurs at both chain ends. However, analogous studies of near stoichiometric processes suggested that propagation is faster at one chain end, particularly when the chains are short. In addition, experiments involving [Ph3P=N=PPh3][PCl6] ([9][PCl6]) and the N-silylphosphoranimines R3P=NSiMe3 3a (R = Ph) and 3b (R = p-CF3C6H4), showed that the [PCl6]- anion, which is formed in the early stages of the polymerization and has hitherto been assumed to be an innocent spectator counteranion, is actually reactive under the reaction conditions and can initiate oligomerization and polymerization. Finally, the absence of reactions between phosphoranimines 3b or 1 with the Cl- salts of the cations [Ph3P=N-PCl2=N=PPh3]+ ([10a]+), [Ph3P=N-(PCl2=N)2=PPh3]+ ([5]+), and [Ph3P=N-(PCl2=N)3=PPh3]+ ([8]+) with P-Cl bonds located internally but not at the chain ends have shown that chain branching reactions are unlikely to be significant during the polymerization. These results identify key factors that complicate the living PCl5-initiated chain growth polycondensation of 1 and potentially lead to a loss of control over molecular weight and broaden the molecular weight distributions, but also indicate that the polymer formed is essentially linear rather than branched.

Reactions of Cp*PCl2 with Group 13 reducing agents result in a cascade of P-C, P-P and C-C bond forming reactions and the stereoselective formation of P2C10 cages.

Abstract Reaction of the C 2-symmetric "Trost modular ligand" with cationic Pd(II) allyl fragments allows isolation of air- and bench-stable pro-catalysts for the asymmetric allylic alkylation of racemic cycloalkenyl esters. In solution, three distinct complexation modes are observed. When mixed in a ligand/Pd ratio of 1/2, a binuclear bis-P,O-chelate complex is generated. This species does not induce enantioselectivity in the reaction. In contrast, with a ligand/Pd ratio of 1/1, a highly enantioselective, P,P-coordinated pro-catalyst system is generated in which there are two basic coordination modes: monomeric and oligomeric. The monomeric form is mononuclear and exists as two 13-membered chelates, isomeric through loss of C 2-symmetry in the ligand. The oligomeric form is polynuclear and forms chains and rings of alternating ligand and cationic Pd(allyl) units, one of which was identified by single-crystal X-ray diffraction. In solution, the monomeric and oligomeric species are in dynamic equilibrium with populations and interconversion rates controlled by concentration, temperature, and counterion. Isotopic desymmetrization analysis suggests that the monomer-oligomer equilibrium plays a crucial role in both the selectivity and efficiency of the asymmetric allylic alkylation reaction.

NMR studies on isotopically desymmetrized ligands and substrates have been used to demonstrate and investigate an apparent "memory effect" in palladium-catalysed nucleophilic substitution at allylic centres. The explanation for this "memory effect" is shown to be the participation of both monomeric and oligomeric complexes, with different reaction rates.

The scalar couplings between hydrogen bonded nitrogen centres ((2H)J(NN)) in the free-base and protonated forms of the complete series of [(15)N(2)]-N-methylated 1,8-diamino naphthalenes in [D(7)]DMF solution have been determined, either directly (15N[1H] NMR), or, indirectly (13C[1H] NMR and simulation of the X part of the ABX spectrum (X=13C, A,B=15N)). Additionally, the (2H)J(NN) value in the HBF(4) salt of [(15)N(2)]-1,6-dimethyl-1,6-diazacyclodecane was determined, indirectly by 13C[(1H] NMR spectroscopy. As confirmed by DFT calculations and by reference to CSD, the rigid nature of the naphthalene scaffold results in rather low deviations in N,N distance or H-N,N angle within each series, apart from the free base of the permethylated compound (proton sponge) where the naphthalene ring is severely distorted to relieve strain. Despite such restrictions, the (2H)J(NN) values increase smoothly from 1.5 to 8.5 Hz in the protonated series as the degree of methylation increases. The effect in the free-base forms is much less pronounced (2.9 to 3.7 Hz) with no scalar N,N coupling detected in the permethylated compound (proton sponge) due to the lack of hydrogen bond between the N,N centres. Neither the pK(a) nor the N-N distance in the protonated forms correlates with (2H)J(NN). However, the sum of the (13)C NMR shifts of the naphthalene ring C(1,8) carbons which are attached directly to the nitrogen centres correlates linearly with (2H)J(NN) and with the degree of methylation. The gas-phase computed (2H)J(NN) is almost constant throughout the homologous series, and close to the experimental value for the tetramethylated ion. However, the computed coupling constant is attenuated in structures involving microsolvation of each N-H unit, and the trend then matches experiment. These experimental and computational observations suggest that Fermi contact between the two N centres is decreased upon formation of strong charge-dispersing intermolecular hydrogen bonds of the free N-H groups with the solvent.

Whereas the cations [CpMo{P(OMe)(3)}(2){eta(2)(4e)-alkyne}](+) do not react with alkynes or P=CBut, the newly synthesized isostructural phosphaalkyne complex [CpMo{P(OMe)(3)}(2){eta(2)(4e)-P=CBut}][B(C6F5)(4)], which is unreactive towards PhC2Ph, readily reacts via an associative stepwise process with P=CBut to give [CpMo{P(OMe)(3)}(2){eta(4)-1,3-P2C2Bu2t}][B(C6F5)(4)]. A further interesting difference in alkyne and phosphaalkyne chemistry was observed when it was found that CpMoCl(CO){eta(2)(4e)-PhC2Ph} reacts with TlPF6 and P=CBut to give the unusual 16-electron cyclocotrimerization product [CpMo{=C(Bu-t)PC(Bu-t)=PC(Ph)=C(Ph)}(CO)][PF6], identified by single-crystal X-ray crystallography.

UV irradiation of a number of N-alkenyl-substituted maleimide derivatives leads to the formation of complex perhydroazaazulenes in excellent yields. The overall process can be considered as a formal intramolecular [5+2] cycloaddition. Substrates were prepared by Mitsunobu coupling of the appropriate alkenols with various maleimides. Methyl substitution of the alkenyl side chain gave the cycloadducts 13a−g in good yields, with moderate to high stereoselectivity being observed for 13e and 13g, respectively. Use of cyclic alkene side chains led to the formation of tri- and tetracyclic products with high degrees of stereoselectivity in most cases. Some of the polycyclic ring systems that were prepared constitute the core skeleton of a number of complex alkaloids. The substrate 29 underwent an unexpected [2+2] photocycloaddition to yield the unusual cyclobutane 31.

Using azomethine ylid reactivity available from the β-lactam-based oxazolidinone 1, selenoketones 6a–e react as 1,3-dipolarophiles to give racemic selenapenams 7a–e in a single step. The cycloaddition sequence proceeds with complete control of regiochemistry and the thermodynamically more stable C(3)/C(5) relationship is observed. The selenothiocarboxylate 9a and the selenocarboxylate 9b also function as effective dipolarophiles, but attempts to convert the resulting cycloadducts 10a and 10b to the corresponding selenapenems were unsuccessful. Other selenium-containing dipolarophiles failed to give characterizable cycloadducts.

The C-2-symmetric ("[DL]") and achiral ("[meso]") diastereoisomers of the hydrogen iodide salt of 1,8-bis-(N-benzyl-N-methylamino)naphthalene ([2H](+)[I](-)) interconvert in solution. Direct interconversion of the diastereoisomers of [2H](+) must involve hydrogen bond fission (to give "[nonHB-2H(+)]'') and rotation-inversion of the non-protonated nitrogen centre. The global activation parameters (DeltaH(not equal) and DeltaS(not equal)) for diastereoisomer interconversion in [D-7]DMF have been determined from rate data obtained by temperature-drop and magnetisation-transfer C-13 NMR spectroscopy over a temperature range of 170 degreesC. The process is found to have a high entropy of activation in both directions (DeltaS(not equal) = 163(+/-4) and 169(+/-4) J K-1 mol(-1)) and this is suggested to arise through hydrogen bonding of the ammonium centre in [nonHB-2H(+)] with the solvent ([D-7]DMF). Comparison of the enthalpy of activation (DeltaH(not equal)) with that earlier found for diastereoisomer interconversion of the free-base form 2 suggests that the intramolecular hydrogen bond in [2H](+) is roughly equal in enthalpic strength (DeltaH) with that made with the solvent ([D-7]DMF) in the non-hydrogen-bonded intermediate [nonHB-2H(+)]. As such, the hydrogen bonding in [2H](+) may be considered as predominantly an entropically driven process, without any unusual enthalpic strength.

Allylindium reagents, prepared from excess allylic halide (Br or I) and indium metal, react with alpha,beta-unsaturated ketones and aldehydes to give, after aerobic acidic workup, homoallyl-substituted vinylcyclopropanes. This process was explored and developed after a chance discovery arising from a side reaction in an attempted Pd-catalysed process. The structure of the cyclopropane arising from the reaction of bis(p-chlorobenzylidine)acetone was confirmed by X-ray crystallography. Whilst bis-alpha,beta-unsaturated ketones give rise to a single homoallylcyclopropane species, alpha,beta-unsaturated ketones and aldehydes give diastereomeric mixtures whose relative stereochemistry were assigned by NOE experiments. Crotylindium reagents react with good to perfect regioselectivity to afford tetrasubstituted cyclopropanes but prenylindium reagents fail to generate the analogous pentasubstituted rings.

The axially chiral ligands 2-(diphenylphosphanyl)-2'-methoxy-1,1'-binaphthalene (MOP; 6) and 2'-dimethylamino-2-(diphenylphosphanyl)-1,1'-binaphthalene (MAP; 7) coordinate to a cationic allylpalladium fragment in an unusual bidentate (P,C)-mode through the triarylphosphane and ipso-carbon atom (C1'). The readily prepared MAP and MOP complexes [Pd[(P,C)-(L)](n3-allyl)][OTf] (9 (L = 7) and 10 (L = 6)) have been characterised in solution (NMR), in which two diastereoisomeric rotamers are observed. The stereochemical identity of the rotamers is established by one- and two-dimensional NMR spectroscopy experiments. In both the solid state and in solution, the allyl unit is shown to coordinate in a slightly distorted n3-mode that results in a more alkene-like character at the allyl terminus trans to phosphane ligand. The opposite allyl terminus, which is trans to the ipsocarbon atom (C1'), is more strongly bound and the dominant allyl stereodynamic process involves C-C bond rotation in an n'-allyl intermediate bound through this carbon. Palladium complexes of MAP and MOP are very efficient catalysts for allylic alkylation of racemic cyclopentenyl pivalate with [NaCH(CO2Me)2] in THF. Isotopic desymmetrisation revealed that the reaction occurs with powerful stereochemical memory effects and consequently with low global ee values. The memory effect is suggested to arise through selective generation of diastereoisomeric [Pd[(P,C)-L](n3-cyclopentenyl)]+ ions (L = MAP or MOP) and subsequent capture by nucleophile before ion-pair collapse or equilibration occurs.

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Racemic 2,2′-bis(pyridin-2-yl)-1,1′-binaphthalene (±)-6 was prepared in four synthetic steps from 2-naphthol. Resolution of the novel atropisomeric ligand 6 was effected by repeated preparation, recrystallisation and then liberation of the bis-tartrate salt (D and L). This affords both enantiomers of 6 (>96% enantiomeric excess, ee) whose absolute configurations were assigned by CD. The ligand 6 is stable towards racemisation (ΔG‡rac > 167 kJ mol−1) and the structure was confirmed by single crystal X-ray diffraction of the complex [ZnCl2(6)]. The structure and stereodynamics of the complex [Pd(η3-C3H5)(6)][OTf] (OTf = O3SCF3) which comprises a C2-symmetric ligand bound via Pd to a non-C2-symmetric allyl fragment was studied in detail in solution by 1-D and 2-D 1H NMR and in the solid state by single crystal X-ray diffraction. Apparent stereodynamic processes of the allyl ligand, as detected in solution by NMR, are shown to arise from ligand 6 stereodynamics and exchange. The ligand 6 represents the first compound/building block for a series of enantiomerically pure N,N-ligands that may be of utility in supramolecular co-ordination chemistry and in asymmetric catalysis.

The structures and relative stereochemistries of walleminol (1) and walleminone (2), novel cis-fused iso-caryophyllenes from the toxigenic fungus, Wallemia sebi, have been established by detailed high-field 1D and 2D NMR and X-ray crystallographic studies.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPalladium(II) Complexes of 2-Dimethylamino-2‘- diphenylphosphino-1,1‘-binaphthyl (MAP) with Unique P,Cσ-Coordination and Their Catalytic Activity in Allylic Substitution, Hartwig−Buchwald Amination, and Suzuki CouplingPavel Kočovský, Štěpán Vyskočil, Ivana Císařová, Jan Sejbal, Iva Tišlerová, Martin Smrčina, Guy C. Lloyd-Jones, Susanna C. Stephen, Craig P. Butts, Martin Murray, and Vratislav LangerView Author Information Department of Chemistry, University of Leicester Leicester LE1 7RH, U.K. Department of Organic Chemistry, Charles University 128 40, Prague 2, Czech Republic School of Chemistry, University of Bristol Bristol BS8 1TS, U.K. Department of Inorganic Environmental Chemistry Chalmers University of Technology, 41296 Göteborg, Sweden Cite this: J. Am. Chem. Soc. 1999, 121, 33, 7714–7715Publication Date (Web):August 6, 1999Publication History Received1 February 1999Published online6 August 1999Published inissue 1 August 1999https://doi.org/10.1021/ja990309mCopyright © 1999 American Chemical SocietyRequest reuse permissionsArticle Views1893Altmetric-Citations154LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (50 KB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Chemical structure,Ligands,Mixtures,Organic reactions,Palladium Get e-Alerts

The homochiral form of the complex [(‘P,N’)2Ni]2+ (‘P,N’ is a phosphino–heteroatom bidentate ligand) has been found to be more stable than its heterochiral analogue due to a ‘fitting’ of the two ‘P,N’ ligands about the Ni that is reminiscent of an ‘intramolecular embrace’.