Crystal Structures Of 2b Research Articles

Site-selective substitution and vinylidene–alkylidyne–vinylidene interconversion in dimolybdenum–ruthenium clusters

The thermal reaction of the dimolybdenum–ruthenium vinylidene clusters [Mo 2 Ru(µ 3 -CCHR)(CO) 7 (η-C 5 H 5 ) 2 ] (R = H 1a, Me 1b, Ph 1c or CO 2 Me 1d) with the tertiary phosphine PPh 2 Me afforded the monosubstituted complexes [Mo 2 Ru(µ 3 -CCHR)(CO) 6 (PPh 2 Me)(η-C 5 H 5 ) 2 ] 2a–2d in excellent yields. The products exist as single isomers in which site-selective substitution of a CO ligand has occurred exclusively at the ruthenium atom. The crystal structure of 2b has been determined by X-ray diffraction; the geometry of the vinylidene ligand is identical to that previously found in the parent compound 1b, but a slightly different pattern of semi-bridging carbonyls is present. The reactions of 1a and 1b with diphenylphosphine are more complex. Depending on the stoichiometry and conditions employed, three different types of cluster have been isolated: the substitution product [Mo 2 Ru(µ 3 -CCH 2 )(CO) 6 (PPh 2 H)(η-C 5 H 5 ) 2 ] 2e; the 46-electron monophosphido compounds [Mo 2 Ru(µ 3 -CCH 2 R)( µ-PPh 2 )(CO) 5 (η-C 5 H 5 ) 2 ] 3a, 3b and the saturated bis(phosphido) species [Mo 2 Ru(µ 3 -CCHR)(µ- PPh 2 ) 2 (CO) 4 (η-C 5 H 5 ) 2 ] 4a, 4b. Separate experiments have established that these products are formed sequentially, thus demonstrating the conversion of the initial vinylidene into an alkylidyne ligand and then back to a vinylidene. The structures of 3b and 4a have been confirmed by X-ray diffraction, showing that the phosphido groups bridge one or both of the Mo–Ru edges respectively.

Synthesis and Characterization of New Lithiated Organogermanium Compounds

New (8-methoxy-1-naphthyl)arylgermanes 1a−c are synthesized. The crystal structure of 1b (aryl = mesityl), determined by X-ray diffraction, shows that an intramolecular interaction occurs between the oxygen and germanium atoms, the Ge- - -O distance being 2.75 Å. The corresponding (diarylgermyl)lithiums R2HGeLi are prepared in high yield by hydrogermolysis of tert-butyllithium in THF and are susprisingly stable. Their characterization by 1H, 13C, and 7Li NMR spectroscopy is reported. Dimetalation of the initial arylgermanes depends upon steric hindrance around the germanium atom and the nature of the organolithium compound RLi. The reaction of 1a or 1c with n-BuLi followed by MeI affords the expected dialkylation product, whereas 1b gives the unexpected iodide 5b due to steric hindrance around the germanium atom.

Photochemical reaction of ( η5-cyclopentadienyl) dicarbonyliron iodide with 1-substituted uracils in the presence of diisopropylamine: crystal structure of the ( η5-C 5H 5Fe(CO) 2 complex of deprotonated 5-fluoro-1-(tetrahydro-2-furyl) uracil (Ftorafur)

Irradiation with visible light of a mixture of Fe(Cp)(CO) 2I (Cp = η 5-cyclopentadienyl) with 1-methyyluracil ( 1a), 5-fluoro-1-(tetrahydro-2-furyl)uracil (Ftorafur) ( 1b) or 6-azauridine-2′3′5′-triacetate ( 1c) in the presence of diisopropylamine affords complexes in which the Fe(Cp)(CO) 2 moiety is bound to the deprotonated N(3) atom of the uracil moiety. The crystal structure of 2b, made from 1b, was determined and is compared with the known structures of the α A, α B and β forms of Ftorafur and that of its η 1-Au complex. Complex 2b shows the shortest intramoleculaar CH …O hydrogen bond between the tetrahydrofuran and uracil rings. The stereochemistry of this complex is also discussed.

Metallkomplexe mit biologisch wichtigen Liganden, LXX. Synthese, Stereochemie und Reaktionen von Ruthenium(II) und Osmium(II)‐Komplexen mit α‐Aminocarboxylat‐Liganden

Metal Complexes of Biologically Important Ligands, LXX[1].‐ Synthesis, Stereochemistry and Reactions of Ruthenium(II) and Osmium(II) Complexes with α‐Amino CarboxylatesHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet. The reactions of MHCl(CO)(PPh3)3 with salts of α‐amino acids give the hydrido‐N,O‐chelate complexes MH(CO)(NH2CHR‐COO)(PPh3)2 (1a–g;) M = Ru, Os). Complexes 1a–c can alternatively be prepared by oxidative addition of the appropriate α‐amino acid to Ru(CO)3(PPh3)2. The crystal structure of 1b has been determined by an X‐ray structural analysis. The leucinato compound 1c is an effective catalyst for the decomposition of formic acid. In contrast, reactions of RuHCl‐(CO)(PPh3)3 with α‐amino acids afford the chloro‐N,O‐che‐late complexes RuCl(CO)(NH2CHRCOO)(PPh3)2 2a–h. The decomposition reactions of 2c, 2g and2h have been investigated.

Preparation and characterisation of bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)copper(II) complexes with diazaaromatic compounds. Part 1. Crystal structures and characterisation of several adducts with diazines

The reactions of [Cu(hfac)2](Hhfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione) with diazines (tmpyz = 2,3,5-trimethylpyrazine, mpym = 5-methylpyrimidine and mpydz = 3-methylpyridazine) in light petroleum have been studied and the following complexes obtained: [{Cu(hfac)2}3(µ-tmpyz)2]1b, [Cu(hfac)2(tmpyz)]1e, [{Cu(hfac)2(µ-mpym)n}]2a, [{Cu(hfac)2}3(µ-mpym)2]2b, [{Cu(hfac)2}2(µ-mpym)]2c, [Cu(hfac)2(mpym)2]2d, and [Cu(hfac)2(mpydz)2]3d. The crystal structures of 1b, 2b and 3d have been determined. Although 1b and 2b are both trinuclear complexes with bridging diazole molecules, the geometry around atom Cu(2) is trigonal bipyramidal for 1b and tetragonal pyramidal for 2b. The geometry around atom Cu(1) is tetragonal bipyramidal in both complexes. The distance Cu(1)–N(1) is longer in 1b than in 2b, while the Cu(2)–N(2) is somewhat shorter in the former. The steric effects of the ligands on the structural differences between these complexes are discussed. On the basis of the relation between the geometry of the co-ordinated hfac ligands and ν(C–O) values, structures of some of the other complexes are suggested.

Enantioselective alkylating reagents; crystal structure of [Ru{η5C5H4(C10H19)}(dppe)(IEt)]CF3SO3[dppe = PPh2CH2CH2PPh2, C10H19=(+)-neomenthyl

The complex [Ru{η5-C5H4(C10H19)}(dppe)I]1[dppe = PPh2CH2CH2PPh2, C10H19=(+)-neomenthyl] reacts with CF3SO3R (R = Me or Et) to give the corresponding alkyl iodide complexes [Ru{η5-C5H4(C10H19)}(dppe)(IR)]CF3SO3(R = Me 2a or Et 2b) which alkylate a range of prochiral nucleophiles (e.e. ⩽20%) to regenerate 1; the crystal structure of 2b is reported.

The photochemical properties of the mono‐and dithioimide derivatives of (E,E)‐dibenzylidene‐N‐phenylsuccinimide

AbstractNovel (E,E)‐dibenzylidene‐N‐phenyl succinimide thioimide 1b and dithioimide 1c derivatives of the photochromic fulgimide 1a were synthesized. The thioimide 1b and dithioimide 1c derivatives were found to undergo isomerization as the main photoreaction when irradiated in a variety of organic solvents, as opposed to the reversible electrocyclic ring closure/opening reactions in the case of the fulgimide 1a. The X‐ray crystal structures of 1b and 1c were determined, and the influence of the thiocarbonyl groups on the structural parameters were investigated in comparison to the crystal structure of 1a. The 1H and 13C NMR spectra were recorded for all three compounds 1a, 1b, and 1c and are discussed in terms of their structural and electronic variations, as is the effect on the photochemical behavior. The twisting of the N‐phenyl ring was found to be a consequence of intramolecular steric interactions and not of intermolecular packing forces. This was substantiated by a series of semiempirical (AMI) calculations. The C(thiocarbonyl) was found to be highly deshielded compared to the corresponding C(carbonyl) carbon atom, and the deshielding effect of the thiocarbonyl group was evident throughout the whole thiocinnamic moiety. Crystal data for monothioimide 1b: spacegroup P21/c with a = 8.794(2) Å, b = 9.623(1) Å, c = 22.182(5) Å, β = 91.45(2)°, Rw = 0.038, and R = 0.067. Dithioimide 1c: spacegroup Pnna with a = 9.411(2) Å, b = 17.304(2) Å, c = 13.574(2) Å, Rw = 0.055, and R = 0.077.

Nitrosyl Complexes. 6. Reactions of Na[Fe(CO)3NO] with Cp*M(CO)3Cl (Cp*=η5−CH3C5H4, M = Mo or W): Crystal structures of Cp*M(CO)2NO and Cp*M(μ3‐NH)(μ2‐NO)(μ2‐CO)Fe2(CO)6

AbstractSodium nitrosylcarbonyliron reacts with methylcyclopentadienylcarbonylmetal (Mo or W) chloride in CH3OH/THF at room temperature to give Cp*Mo(CO)2NO(la) (Cp* = η5−CH3C5H4) or Cp*W(CO)2NO (1b), [Cp*Mo(CO)3]2 (2a) or [Cp*W(CO)3]2 (2b), and Cp*Mo(μ3‐NH)(μ2‐NO)‐(μ2‐CO)Fe2(CO)6 (3a) or Cp*W(μ3‐NH)(μ2‐NO)(μ2‐CO)Fe2(CO)6 (3b), respectively. Complexes 1a, 1b, 3a and 3b were analyzed by IB, NMR, MS and elemental analyses, and the crystal structures of 1b, 3a and 3b were determined by X‐ray diffraction method. The new clusters 3a and 3b have μ3‐NH ligands which were formed by reduction of NO in the synthetic reactions.

Phosphane‐borane chemistry. Open‐chain and cyclic phosphane‐boranes based on tetramethyldiphosphane

Abstract1:2 addition compounds of tetramethyldiphosphane with BH3, BH2Br, BHBr2, and BBr3 (1a–d) have been prepared from the parent diphosphane and the dimethyl sulfide complexes of the boranes in the appropriate stoichiometric ratio. Open‐chain and cyclic phosphane‐borane cations were obtained from Me4P2 and H2BrB · SMe2 in the molar ratio 2:1 or 1:1, respectively: [Me2PPMe2 · BH2 · PMe2  PMe2]+Br− (2) or [H2B(Me2PPMe2)2‐ BH2]2+2Br− (3). Treatment of 1b with trimethylphosphane yields the salt [H2BrB·Me2PPMe2 · BH2 · PMe3]+Br− (4). – The crystal structures of 1b and 3 · 2MeOH have been determined by single‐crystal X‐ray diffraction methods. Molecules 1b have crystalographic C2h symmetry corresponding to the anti‐configuration of the diphosphane and staggered conformation of the BH2Br moieties. The monomers are arranged in layers with Br …︁ Br contacts of 3.66 Å. – Crystals of 3 · 2 MeOH have an ionic structure built from bromide ions, interstitial methanol molecules, and crystallographically centrosymmetric dications [H2B(Me2PPMe2)2‐BH2]2+. These dications are in a chair configuration approaching (non‐crystallographical) mirror symmetry. The intra‐ring valence angles at boron [116.2(2)°] are significantly larger than those at phosphorus (108.4°, average). The BP distances are shorter than in standard reference compounds (e.g. 1b), indicating extra stabilisation in the dicationic phosphane‐borane ring system. In the unit cell there are no sub‐van der Waals contacts between the individual components.

Synthese von Bis(η 5 ‐cyclopentadienyl)(1,2,3‐triphenyltriphosphan‐1,3‐diyl)zirconium(IV) und ‐hafnium(IV), (M = Zr, Hf) und Struktur des Hafnocenderivates

Synthesis of Bis(η5-cylopentadienyl)(1,2,3-triphenyltriphosphane-1,3-diyl)zirconium(IV) and -hafnium(IV), (M = Zr, Hf), and Structure of the Hafnocene Derivative The reaction of [MCp2Cl2] (M = Zr, Hf; Cp = η5-C5H5) with [LiPHPh · 2 THF] and of [ZrCp2Me2] with PH2Ph leads to (1a, M = Zr; 1b, M = Hf). The crystal structure of 1b shows that only one diastereomer is present [(R) at P(1), (S) at P(3)] and that the HfP3 metallacycle is virtually coplanar.

Preparation and characterization of (9-methyladenine)triammineplatinum(II) and trans-dihydroxo(9-methyladenine)triammineplatinum(IV) complexes

The preparation is reported of [(NH 3) 3Pt(9- MeA)] X 2 (9-MeA = 9-methyladenine) with XCl ( 1a) and XClO 4 ( 1b) and of trans-[(OH) 2Pt(NH 3) 3- (9-MeA)]X 2 with XCl ( 2a) and XClO 4 ( 2b), and the crystal structure of 1b. [(NH 3) 3Pt(C 6H 7N 5)](ClO 4) 2 crystallizes in space group P2 1/n with a = 20.810(7) Å, b = 7.697(3) Å, c = 10.567(4) Å, β = 91.57(6)°, Z = 4. The structure was refined to R = 0.054, R w = 0.063. In all four compounds Pt coordination is through N7 of 9-MeA, as is evident from 3 J coupling between H8 of the adenine ring and 195Pt. Pt(II) and Pt(IV) complexes can be differentiated on the basis of different 3 J values, larger for Pt(II) than for Pt(IV) by a factor of 1.57 (av). In Me 2SO-d 6, hydrogen bonding occurs between Cl − and C(8)H of 9-MeA as weil as between Cl − and the NH 3 groups in the case of the Pt(II) complex 1a. Protonation of the 9-MeA ligands was followed using 1H NMR spectroscopy and pK a values for the N1 protonated 9-MeA ligands were determined in D 2O. They are 1.9 for 1a and 1.8 for 2a, which compares with 4.5 for the non-platinated 9-MeA. Possible consequences for hydrogen bonding with the complementary bases thymine or uracil are discussed briefly. Protonation of the OH groups in the Pt(IV) complexes has been shown not to occur above pH 1.

Structural Studies of 1,8‐Disubstituted Naphthalenes as Probes for nucleophile‐electrophile interactions

AbstractResults of crystal structure analyses of seven 1, 8‐disubstituted naphthalenes (2a, 8‐(N,N‐dimethylamino)‐1‐naphthyl methyl ketone; 2b, 8‐(N, N‐dimethylamino)naphthalene‐1‐carboxylic acid; 2c, methyl 8‐(N, N‐dimethylamino)naphthalene‐1‐carboxylate; 2d, 8‐methoxy‐1‐naphthyl methyl ketone; 2e, 8‐methoxynaphthalene‐1‐carboxylic acid; 2f, N, N‐dimethyl‐8‐methoxynaphthalene 1‐carboxamide; 2g, N, N‐dimethyl‐8‐hydroxynaphthalene‐1‐carboxamide) with a nucleophilic centre (N(CH3)2, OCH3, OH) at one of the peri positions and an electrophilic centre (carbonyl C) at the other are described. All seven molecules show a characteristic distortion pattern: the exocyclic bond to the electrophilic centre is splayed outward, and the one to the nucleophilic centre is splayed inward; the carbonyl C is displaced from the plane of its three bonded atoms towards the nucleophile. This distortion pattern differs from that found in other 1,8‐disubstituted naphthalenes and is interpreted as an expression of incipient nucleophilic addition to a carbonyl group. The crystal structure of 2b contains an ordered arrangement of equal numbers of amino acid and zwitterionic molecules.