Showing papers by "Martin Lutz published in 2001"
TL;DR: In this paper, a novel strategy for the preparation of rigid cartwheel pincer metal complexes has been developed, which ensures a high rigidity, which is expected to be important for a high retention when these multimetallic nanosize complexes are applied as homogeneous catalysts in a nanomembrane reactor.
119 citations
TL;DR: In this article, the potential tridentate P-stereogenic [P*CP*]ligands 1,3-{bis[(tert-butyl)(phenyl) phosphino]methyl}-2bromobenzene have been synthesized as theprotectedphosphine-boraneadducts.
Abstract: )BijvoetCenterforBiomolecularResearch,CrystalandStructuralChemistry,UniversiteitUtrecht,Padualaan8,3584CH,Utrecht,TheNetherlandsInmemoriamProfessorLuigiM.Venanziforhispioneeringworkinorganometallicchemistry,andinPCP-pincerchemistryinparticularThepotentiallytridentateP-stereogenic[P*CP*]ligands1,3-{bis[(tert-butyl)(phenyl)phosphino]methyl}-benzene and 1,3-{bis[(tert-butyl)(phenyl) phosphino]methyl}-2-bromobenzene have been synthesized as theprotectedphosphine-boraneadducts.Deprotectionwithasecondaryamineaffordsthefreephosphineligandwhich can be metallated by Pd and Pt with standard metal synthons. Two of the resultant [P*CP*] metalcomplexes have been characterized by X-ray crystallography. The complexes exhibit a C
76 citations
TL;DR: A series of cyclopalladated carbosilane dendrimers functionalized with monoanionic [C6H4(CH2NMe2)-4]- (= CN) C,N-chelating ligands via a multiple and selective C-H bond activation process have been prepared in this paper.
58 citations
TL;DR: The first platinum(II) halogenide compounds containing the (σ3-N,C,N)isophtalaldimine ligand, 2a and 2b, have been prepared via an oxidative addition of the bromoisophthalaldimines ligands 1a and 1b as mentioned in this paper.
55 citations
TL;DR: In this article, vanadium-based catalysts have been used in the synthesis of monoanionic, potentially bi- or terdentate aminophenolates for the polymerization of -olefins.
Abstract: Monoanionic, potentially bi- or terdentate aminophenolates, ([OC6H3(CH2NMe2)-2-R-4)]-, R = H (a), Me (b), tBu (c), Cl (d), N=NPh (e), MeO (f) and [OC6H2(CH2NMe2)2-2,6-Me-4]- (g)), have been used in the synthesis of well-defined vanadium-based catalysts for the polymerization of -olefins. The reaction of [Cp2V] with the parent phenol of g resulted in oxidation of the vanadium(II) nucleus to obtain the vanadium(III) (tris)phenolate [V(OC6H2(CH2NMe2)2-2,6-Me-4)3] (1). Vanadium(III) aminophenolates could not be obtained by reaction of [VCl3(THF)3] with the sodium phenolates because of incorporation of NaCl. However, use of the corresponding silyl ether Me3SiOC6H3(CH2NMe2)-2-Me-4 (2) resulted in the formation of the chlorovanadium (bis)phenolate [VCl(OC6H3(CH2NMe2)-2-Me-4)2] (3). Attempts to oxidize 3 to the corresponding dichlorovanadium(IV) (bis)phenolate were not successful. No reaction was observed with CuCl, AgCl and PbCl2. A dark blue compound 4 was obtained with CuCl2, which was tentatively assigned as a VIII/CuII dinuclear species. Treatment of the vanadium(IV) oxo (bis)phenolates 5a-5f with SOCl2 in benzene at room temperature or in toluene at reflux temperature resulted in the formation of dark blue compounds 6a-6f, whose stoichiometries indicated excess chloride. Only when 5a and 5d were reacted with SOCl2 at -70 °C could the desired dichlorovanadium (bis)phenolates [VCl2(OC6H4(CH2NMe2)-2)2] (7a) and [VCl2(OC6H3(CH2NMe2)-2-Cl-4)2] (7d) be obtained. X-ray crystal structure determination of 1 and 3 showed that both compounds have a trigonal bipyramidal geometry with two aminophenolate ligands bound in a bidentate 2-O,N fashion to the vanadium center in similar ways. The compounds 1, 3, 6 and 7 were tested for ethene/propene copolymerization.
40 citations
TL;DR: The reactions of [Ru-(=CHR)Cl2(PCy3)2] with silver salts of carboxylic acids afforded new dimeric complexes of the general formula that are active catalysts for metathesis of acyclic alkenes, including unsaturated fatty acid esters, as well as for ring closing metatheses.
Abstract: The reactions of [Ru-(=CHR)Cl2(PCy3)2] (1: R = Ph; 1a: R = -CH=CPh2) with silver salts of carboxylic acids afforded new dimeric complexes of the general formula [Ru2(=CHR)2-(R'CO2)2(mu-R'CO2)2(PCy3)2(mu-H2O)] (2: R = Ph, R' = CF3; 3: R = Ph, R' = C2F5; 4: R = -CH=CPh2, R' = CF3; 5: R = Ph, R' = C6F5; 6: R = -CH=CPh2, R' = C6F5; 7: R = -CH=CPh2, R'=CCl3) in good yields. With R' = CF3, C2F5 or CCl3 these complexes are active catalysts for metathesis of acyclic alkenes, including unsaturated fatty acid esters, as well as for ring closing metathesis. The reactivity of these complexes with bases and weak donor solvents has been studied and their half-life times in several media were determined.
40 citations
TL;DR: A series of ruthenium benzylidene complexes containing diphosphines (xantphos, dppf, Cy 2 P(CH 2 ) n PCy 2 ( n ˚5, 8)) has been obtained by phosphine exchange in the ruthe-nium carbene complex RuCl 2 (CHPh)(PPh 3 ) 2, or in a one-pot two-step synthesis from RuCl2 (PPh3 ) 3, phenyldiazomethane, and diphophosphine as mentioned in this paper.
35 citations
TL;DR: In this paper, a novel μ-oxo diiron(III) complex is proposed for the selective oxidation of primary and secondary alcohols in the presence of H2O2 and a remarkable increase in reaction rate is achieved by addition of 1 eq.
34 citations
TL;DR: In this paper, a series of homodinuclear Pt compounds containing the anionic, potentially terdentate NCN ligand (NCN [C6H3(Me2NCH2)2-2,6]) or its 4-ethynyl derivative were prepared.
28 citations
TL;DR: A series of cycloplatinated carbosilane dendrimers appended with the monoanionic C, N-bidentate ligand [C{6}H{4}{CH{2}NMe{2]--2]}-{ (CN) was prepared via a multiple C@?H activation reaction.
25 citations
TL;DR: In this paper, the shortest intermolecular O-H-Ph hydrogen bonds known as yet have been found, both in terms of the H···M as well as the O-M distances (2.17 and 3.07 A, respectively).
Abstract: In crystal structures of tetraphenylborate salts with cationic X–OH donors (choline, triethanolammonium
dihydrate, 6-ammonio-n-hexanoic acid monohydrate), the shortest intermolecular O–H···Ph hydrogen bonds known as yet have been found, both in terms of the H···M as well as the O···M distances (2.17 and 3.07 A, respectively, for normalized O–H distance; M = midpoint of the aromatic ring). In these interactions the donor H and O atoms reside roughly over the centroids of the acceptor groups. A supporting database study of very short O–H···Ph hydrogen bonds
has also been made (using the Cambridge Structural Database).
TL;DR: A series of low-spin nickel complexes of the didentate ligand 1,3-bis[di(o-methoxyphenyl)phosphanyl]propane (o-MeO-dppp) has been synthesized and characterized.
Abstract: A series of nickel complexes of the didentate ligand 1,3-bis[di(o-methoxyphenyl)phosphanyl]propane (o-MeO-dppp) has been synthesized and characterized. The first low-spin nickel complex containing two coordinated water molecules, [Ni(o-MeO-dppp)(H2O)2](PF6)2 (1), and compounds of the general formula [Ni(o-MeO-dppp)X2] [X = Cl, Br, I, or trifluoroacetate (TFA)] are reported. Complex 1 has been characterized by X-ray crystallography. The nickel ion resides in a square-planar coordination environment with two phosphorus donors and two water molecules in a cis configuration (Ni−P distance 2.19 A; Ni−O distance 1.97 A). The structure of this complex and its behavior in solution are quite different from those of the complexes [Ni(o-MeO-dppp)X2]. The halide complexes [Ni(o-MeO-dppp)Cl2] (2) and [Ni(o-MeO-dppp)Br2] (3) are seemingly mutually isostructural. In these complexes, the nickel ion also resides in a square-planar geometry, but with a significant tetrahedral distortion. The two different types of mono(o-MeO-dppp)nickel(II) complexes, i.e. [Ni(o-MeO-dppp)(H2O)2](PF6)2 (1) and [Ni(o-MeO-dppp)X2] [X = Cl (2), Br (3), I, or trifluoroacetate (TFA)] have been analyzed by electronic absorption and NMR spectroscopy. The differences in the crystal structures of 1 and 2 are helpful in rationalizing the fluxional behavior of these complexes, as has been studied by NMR spectroscopy.
TL;DR: Calculations on an unsubstituted, uncomplexed system suggest that the initially formed P,N-ylide of the H2C=N-(CH)2-N=CH2 diimine both kinetically and thermodynamically favors an intramolecular 1,3-dipolar cycloaddition over an imine insertion into the CPN ring of an intermediate azaphosphiridine.
Abstract: The terminal phosphinidene complex PhPW(CO)5 adds to the imine bond of PhHC=N−Ph to give 3-membered ring azaphosphiridines, which undergo ring-expansion with an additional imine to yield a set of four isomeric five-membered ring diazaphospholanes. Treatment with the diimines PhHC=N-(CH2)n-N=CHPh (n=2,3,4) results instead—in all three cases—in only a single isomer of the (CH2)n bridged diazaphospholane. For n=2 or 3, this aminal group is easily hydrolyzed to afford new 6- and 7-membered ring heterocycles. No intermediate azaphosphiridine complex is observed during the addition reaction to the diimines. B3LYP/6–31G* calculations on an unsubstituted, uncomplexed system suggest that the initially formed P,N-ylide of the H2C=N-(CH)2-N=CH2 diimine both kinetically and thermodynamically favors an intramolecular 1,3-dipolar cycloaddition over an imine insertion into the CPN ring of an intermediate azaphosphiridine. Single-crystal X-ray structures for the (CH2)2-bridged azaphospholane complex and the HCl adduct of the 7-membered hydrolysis product are presented.
TL;DR: In this article, the application of platinum(II) complexes based on the N,N-dimethylbenzylamine ligand (abbreviated as H-C,N) in macromolecular synthesis was demonstrated.
TL;DR: Trimethylsilyl- and dimethyl(1H, 1H, 2H,2H-perfluorooctyl) substituents have been introduced in the para position of tetraphenylborate anions, resulting in enhanced solubility of their complexes n-Bu4N[B(C6H4SiMe2R-4]4] (R = Me, CH2CH2C6F13) and [Rh(dppe)2] (dppe = 1,2-bis(diphenyl
TL;DR: In this paper, a doubly cycloplatinated diaminobenzene (NCN-H, 1) with one or two equivalents of cis-PtCl{2}(DMSO) leads to exclusive formation of the bisphosphine adduct.
TL;DR: The transient electrophilic phosphinidene complex PhPW(CO)5 reacts in the presence of CuCl at room temperature with phospholene 2 and phospholes 4a-c to give the corresponding W(CO)-5 complexed products 3 and 5a−c.
TL;DR: The terminal phosphinidene complex PhPW(CO)5 reacts with 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene to give two unexpected multicyclic organophosphorus compounds that results from an initial 1,2-addition, followed by an intramolecular rearrangement.
Abstract: The terminal phosphinidene complex PhPW(CO)5 reacts with 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene to give two unexpected multicyclic organophosphorus compounds. One of them results from an initial 1,2-addition, followed by an intramolecular rearrangement. B3LYP/6-31G* calculations on simplified parent systems suggest that the reaction follows a unique concerted reaction pathway. The second, and major, product is a tetraphosphaquadricyclane derivative, which presumably results from an intramolecular [2+2] cycloaddition of an intermediate tetraphosphanorbornadiene complex. Single-crystal X-ray structures are presented for both products.
TL;DR: The X-ray crystal structure of 2,5-furan-dione (C4H2O3) was determined at 130'2' K as discussed by the authors, which is the standard.
Abstract: The X-ray crystal structure of the title compound (2,5-furandione), C4H2O3, was redetermined at 130 (2) K. The C=C double bond, previously reported to be unusually short, was accurately measured as 1.3322 (9) A and thus proved to be fairly standard. The relatively high melting point of the compound is attributed to the intermolecular dipole–dipole interactions between carbonyl groups.
TL;DR: In this article, the two lithium atoms bridging the phenyl ortho-carbon atoms in a four-membered ring structure were shown by crystal structure analysis to be dimeric.
TL;DR: The synthesis, structure and photochemistry of the novel rhodium(III) complexes cis,cis -[Rh(R) 2 (I)(CO)(dmb)] (R=Me ( 1 ), i Pr ( 2 )) are reported in this paper.
TL;DR: In this article, achiral molecules, chiral molecules and racemates are briefly reviewed, as well as the phenomenon of spontaneous resolution of the racemic mixture of molecules within one strand, and the reason for the preference of the observed structure o f N-acetyl-DL-alanine methylester over spontaneous resolution is seen in the optimization of hydrogen bonding within a strand versus the overall crystal packing energy.
Abstract: Abstract N-Acetyl-L-alanine methylester crystallizes in the orthorhombic space group P212121 with one molecule in the asymmetric unit (a = 7.768(1), b = 9.606(1), c = 10.215(2) Å, Z = 4). The individual molecules are linked into infinite strands by intermolecular hydrogen bonds between the amide hydrogen atom as donor and the acetyl oxygen atom as acceptor. The strands run parallel to the crystallographic b axis. The respective racemate, N-acetyl-DL-alanine methylester, crystallizes in the monoclinic space group P 21/n with three molecules in the asymmetric unit (a = 14.442(3), b = 8.467(2), c = 19.336(5) Å, β = 93.68(1)°, Z = 12). Again, the individual molecules are linked into infinite strands by N-H···O= Cacetyl hydrogen bonds which run along the crystallographic a axis. The individual strands are made up of molecules of opposite chirality in a 2:1 ratio. More specifically, one set of strands consists of molecules in the sequence [D, D, L,]∞ while a second set has the sequence [L, L, D]∞ as imposed by the centrosymmetry o f the space group. Thus, although crystals o f N-acetyl-DL-alanine methylester contain equal amounts of the molecules of opposite chirality, the strand formation through intermolecular hydrogen bonds leads to an incom plete resolution of the racemic mixture of molecules within one strand. The reason for the preference of the observed structure o f N-acetyl-DL-alanine methylester over spontaneous resolution is seen in the optimization of hydrogen bonding within one strand versus the overall crystal packing energy. Some principles of the crystallization of achiral molecules, chiral molecules, and racemates are briefly reviewed, as is the phenomenon of spontaneous resolution.
TL;DR: The X-ray crystal structure of the title compound, lithium 1,2,3,6-tetrahydro-2,6dioxo-4 pyrimidine-carboxylate monohydrate, Li+·C5H3N2O4−·H2O, was redetermined at a temperature of 110
Abstract: The X-ray crystal structure of the title compound, lithium 1,2,3,6-tetrahydro-2,6-dioxo-4-pyrimidinecarboxylate monohydrate, Li+·C5H3N2O4−·H2O, was redetermined at a temperature of 110 (2) K. It was now possible to locate all H atoms in the difference Fourier map. The hydrogen-bonding pattern can now be completely described, as well as the coordination mode of the water molecule to the lithium center.