2-iodylphenol ethers: preparation, X-ray crystal structure, and reactivity of new hypervalent iodine(V) oxidizing reagents

2-Iodylphenol ethers were prepared by the dimethyldioxirane oxidation of the corresponding 2-iodophenol ethers and isolated as chemically stable, microcrystalline products. Single-crystal X-ray diffraction analysis of 1-iodyl-2-isopropoxybenzene 8c and 1-iodyl-2-butoxybenzene 8d revealed pseudopolymeric arrangements in the solid state formed by intermolecular interactions between IO2 groups of different molecules. 2-Iodylphenol ethers can selectively oxidize sulfides to sulfoxides and alcohols to the respective aldehydes or ketones.     

The preparation and X-ray crystal and molecular structure of (α,1,2-η-6-methylbenzyl) bis(triphenylphosphine)rhodium(I)

Reaction of [RhCl(PPh₃)₃] with [o-MeC₆H₄CH₂MgBr] affords high yields of the non-fluxional complex, [Rh(CH₂C₆H₄Me)(PPh₃)₂] which has been shown crystallographically to contain a 1-3-η-benzyl group bound through the phenyl carbon atom that is not substituted with the methyl group. Crystals of this compound are triclinic, space group P$\text{1}$, with a = 10.561(6). b = 17.705(3), c = 10.934(4) Å, α = 80.69(3), β = 116.86(4), γ = 102.30(4)° and Z = 2. The structure was solved via the heavy-atom method and refined to R = 0.032 using 5379 diffractometer data with I > 1.56(I). Attempts to prepare π-bonded xylylene complexes from this compound by reaction with base have been unsuccessful, but protonation followed by recrystallisation from acetone gives [Rh{(CH₃)₂CO}₂(PPh₃)₂]BF₄.     

X-ray crystal structure of manganese(II) bis(ethylenediphosphinetetraacetato)nickelate(II) hexadecahydrate

X-ray structure analysis of the title compound (diffractometer data, R = 0.061 for 2805 reflections) confirmed the structure proposed on the basis of spectral evidence for the series of isostructural complexes, M₃[NiL₂ (H₂O)₁₆, where H₄L = (HO₂CCH₂)₂PCH₂CH₂P(CH₂CO₂H)₂ and M = Mn, Fe, Co, Ni, Zn or Cd. The compound studied is monoclinic, P2₁/c, a = 9.990(3), b = 28.51(2), c = 14.828(9) Å, β =94.50(5)°, Z = 4. Nickel(II) is coordinated by two P,P-chelating ligand anions in a rather distorted square planar environment. The carboxyl groups of the ligand are not coordinated to nickel; three of them remain free and five are bonded, together with 10 of the total of 16 water molecules, to the manganese(II) ions. The environments of three manganese ions thus formed are all nearly octahedral but differ in the number and bonding mode of the carboxyls (monodentate and/or bridging bidentate). The carboxyl-to-manganese bonds produce a three-dimensional structure of the compound which is further stabilized by hydrogen bonding.     

X-ray crystal structure of racemic bis(ethyl fumarate) (acetonitrile)nickel(0)

The crystal and molecular structure of racemic bis(ethyl fumarate)(acetonitrile) nickel(0) was determined from X-ray diffractometer data. The structure was solved by Patterson and Fourier methods, and refined by least-squares techniques to R = 0.045 for 3034 independent reflections.Crystals are triclinic, space group P$\text{1}$, with Z = 2, in a unit cell of dimensions: a 9.219 (6), b 13.257 (3), c 10.521 (9) », α 92.57 (9)°, β 109.25 (10)°, γ 110.0 (9)°.The coordination around the nickel(0) atom (the four carbon atoms of the HCCH groups, and the N atom of the acetonitrile residue), may be described as planar, with a slightly distorted trigonal symmetry. The conformations of the two ehtyl fumarate residues agree, more or less closely, with the principle of staggered bonds. The torsion angles around the HCCH groups are significantly different from 180°, as observed in other similar complexes. The four asymmetric carbon atoms of a molecule have the same absolute configuration. SSSS and RRRR molecules are present in the unit cell.     

The preparation and crystal structure of bis(bis(diphenyl-phosphino)ethane)carbonylformylosmium(II) hexafluoroantimonatedichloromethane (1/1)

Reaction of trans[Os(CO)₂(dppe)₂]²⁺ with [KHB(OPrⁱ)₃] gives the formyl complex trans[Os(CHO)(CO)(dppe)₂][SbF₆] which is thermally very stable; the crystal structure shows it to have trans stereochemistry and a long Os-C bond.     

N-heterocyclic carbene complexes of Zn(II): synthesis, X-ray structures and reactivity

The synthesis of six novel zinc (II) mono(N-heterocyclic carbene) complexes is described. 1,3-Bis(mesityl)-imidazol-2-ylidene was reacted with the zinc salts ZnX₂ (X=Cl, CH₃COO, PhCOO, and PhCH₂COO) to yield the corresponding monomeric Zn-NHC complex ZnCl₂(NHC)(THF) (1) and dimeric [Zn(OOCCH₃)₂(NHC)]₂ (2), [Zn(OOCPh)₂(NHC)]₂ (3), [Zn(OOCCH₂Ph)₂(NHC)]₂ (4) (NHC=1,3-bis(mesityl)-imidazol-2-ylidene). Reaction of 1 with 2 equivalents of silver trifluoromethanesulfonate yielded monomeric Zn(O₃SCF₃)₂(NHC)(THF) (5), reaction of 1 with sodium {[R(+)-α-2-(1-phenyl-ethylimino)-methyl]-phenolate} yielded monomeric ZnCl(OC₆H₄-2-CHN(CHPhCH₃)(NHC) (6). Compounds 1, 4-6 were structurally characterized by X-ray analysis. Selected compounds were investigated for their activity in the copolymerization of carbon dioxide with cyclohexene oxide as well as in the ring-opening polymerization of cyclohexene oxide and ε-caprolactone.     

Synthesis, structure, and reactivity of a stabilized calcium carbene: R(2)CCa

Attempted 2-fold deprotonation of the bis(iminophosphorano)methane ligand, H(2)C(Ph(2)P=NSiMe(3))(2) (4-H(2)), with a calcium amide led only to mono-deprotonation. The crystal structure of (4-H)(2)Ca shows two tridentate ligands with short Ca-N and a rather long Ca-C bond. Reaction of 4-H(2) with a dibenzylcalcium complex gave the desired 2-fold deprotonation and formation of 4-Ca, which crystallized as a dimeric complex. Analysis of the calculated atomic and group charges in 4-H(2), (4-H)(2)Ca, and [4-Ca](2) showed that the negative charge at the imine nitrogens only slightly increases upon successive deprotonation of 4-H(2). The electron density at the central carbon, however, increases considerably: the charge on the carbene carbon in [4-Ca](2) is ca. -1.8. The negative charge in 4(2)(-) is therefore mainly located on the carbon. Reaction of [4-Ca](2) with benzophenone in benzene gave the remarkably stable adduct [4-Ca](2) x O=CPh(2), which was characterized by X-ray diffraction. Reaction of [4-Ca](2) with adamantylcyanide gave exclusive formation of the adduct [4-Ca](2) x (N identical withCR)(2), which did not react further, even at higher temperatures. Addition of cyclohexyl isocyanate to a benzene solution of [4-Ca](2) gave immediate [2 + 2]-cycloaddition and formation of a dianionic tetradentate ligand that binds to Ca(2+) through two nitrogens, the central carbon, and an oxygen. This product crystallized as a dimer with bridging oxygen atoms.     

Preparation and crystal structure of dual-functional precursor complex bis(acetylacetonato)nickel(II) with 4-pyridyltetrathiafulvalene

A tetrathiafulvalene (TTF) derivative 4-pyridyltetrathiafulvalene (Py-TTF) was synthesized. The 1:2 Ni complex 1 of bis(acetylacetonato)nickel(II) coordinated with Py-TTF was prepared. Complex 1 crystallizes in the monoclinic space group P2(1)/c. Two pyridyl N atoms from two different molecules of Py-TTF are coordinated in the trans configuration to the Ni ion of Ni(acac)2 to form an octahedral Ni complex, which is a precursor for both conducting and magnetic materials.     

Preparation, crystal structure, and reactivity of bis {tris(trimethylsilyl) methyl} magnesium

Heating of the lithium magnesate [Li(THF)₂(μ-Br)₂Mg(Tsi)(THF)] (Tsi = (Me₃Si)₃C) under vacuum gives the dialkylmagnesium compound Mg(Tsi)₂, the first two-coordinate magnesium derivative to have been structurally characterized in the solid state. The compound is remarkably thermally stable, not decomposing (or melting) when heated to 350°C. It has a very low reactivity, failing to react in toluene with, for example, CO₂, Me₃SiCl, Me₂SiHCl, MeI, BCl₃ or CH₃COCl, and even with neat CH₃COCl at its boiling point. It does react, though fairly slowly, with I₂ in toluene to give TsiI, and more rapidly with Br₂ to give TsiBr, and with an excess of PhSO₂Cl in toluene at 1OO°C to give TsiCl. It decomposes quickly in the air, and reacts readily with MeOH in toluene to give TsiH without formation of detectable amounts of the intermediate TsiMgOMe, and with O₂ in toluene.     

Synthesis, structure and reactivity of new yttrium bis(dimethylsilyl)amido and bis(trimethylsilyl)methyl complexes of a tetradentate bis(phenoxide) ligand

The reactions of a bulky amino-methoxy bis(phenolate) ligand H₂L with Y(CH₂SiMe₃)₃(THF)₂ and Y[N(SiHMe₂)₂]₃(THF)₂ under mild condition leads to the selective formation of the thermally stable complexes [L]Y(CH₂SiMe₃)(THF) (1) and [L]Y[N(SiHMe₂)₂](THF) (2). The X-ray structures revealed very similar binding of the [ONOO] ligand core to the metal for both complexes, which feature an octahedral geometry involving coordination of the methoxy side-arm of the ligand and of a remaining THF molecule. ¹H-NMR spectroscopy indicates that the solid state structure of 1 and 2 is retained in hydrocarbon solutions with THF coordinated to yttrium. Alkyl complex 1 showed no activity in ethylene polymerization, presumably due to the presence of coordinated THF. The amido complex 2 catalyzed sluggishly the polymerization of methyl methacrylate to give isotactic-rich PMMA but is very active for the ring-opening polymerization of ε-caprolactone.     

Synthesis of pyridinium ylide complexes of methylcobaloxime and crystal structure determination of [benzoyl(1-pyridinio)methanide]bis(dimethylglyoximato)methylcobalt benzene solvate

Summary Pyridinium ylide complexes of methylcobaloxime were synthesized by the treatment of an ylide with Co(Hdmg)₂ Me(SMe₂). The crystal structure of one of the complexes, [Co(Hdmg)₂Me C₅H₅NCHCOPh]C₆H₆ has been determined by x-ray diffraction techniques. The crystals are monoclinic, space group P2₁/c, witha = 10.456(5),b = 11.079(4),c = 24.58(1) Å, = 99.58(6), V = 2808 ų, Z = 4. The Co-C (ylide) bond distance is 2.18 Å and Co-C(methyl) 2.04 Å. C(ylide)-Co-C(methyl) bond angle is 174.9°. The crystal, i.r. and¹H n.m.r. data suggest that thetrans-influence of the ylide ligands is larger than that of py, Melm, OH₂ or PPh₃.     

Synthesis, structure, and reactivity of a zirconocene-carboryne precursor

Transition metal-benzyne complexes have found many applications in organic synthesis, mechanistic studies, and the synthesis of functional materials. In sharp contrast, the reaction chemistry of transition metal-carboryne complexes is virtually unknown although the theoretical calculations indicated that the formation of carboryne (1,2-C2B10H10) and benzyne is very energetically comparable. This communication reports a novel zirconocene-carboranyl complex Cp2Zr(mu-Cl)(mu-C2B10H10)Li(OEt2)2 (1), an efficient precursor of the zirconocene-carboryne species, prepared from the reaction of Cp2ZrCl2 with 1 equiv of Li2C2B10H10 in Et2O. The reactivity studies indicated that 1 resembles zirconocene-benzyne in reactions with polar unsaturated organic molecules. On the other hand, it shows no reactivity toward alkynes and alkenes, a reactivity pattern which is quite different from that of zirconocene-benzyne. This work also furnishes a novel method for the preparation of functional o-carboranes and their metal complexes which cannot be synthesized by other methods presently known.     

Unsymmetrically N,N'-substituted saturated carbenes: synthesis, reactivity and preparation of a rhodium(I) carbene complex

A versatile synthesis of unsymmetrically N,N'-substituted saturated carbenes is described. The novel racemic imidazolidin-2-ylidenes rac-5 have been synthesized by reductive desulfurization of the corresponding imidazolidin-2-thiones rac-4. The thiones were prepared in two reaction steps from aldimines and secondary amines. Three different substituents at N1, N3 and C4 of the five-membered N-heterocyclic ring can be introduced by choice of suitable aldimines and secondary amines. The dimerization behaviour (diaminocarbene/enetetramine equilibrium) for the unsymmetrically N,N'-substituted imidazolidin-2-ylidenes has been investigated by NMR spectroscopy. Unsymmetrically N-iPr and N-iBu substituted N-heterocyclic carbenes undergo a slow dimerization, whereas N-tBu substituted derivatives are stable as monomeric carbenes indefinitely. The carbene ligand rac-5d has been coordinated to rhodium(I) to give the square-planar rhodium carbene complex [Cl(cod)Rh(rac-5d)]rac-6d which has been characterized by an X-ray diffraction analysis.     

Synthesis and reactivity of bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonylmolybdenum and tungsten X-ray crystal structureof bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonyltungsten

Bis(3,5-dimethylpyrazol-1-yl)ethane tetracarbonylmolybdenum (1a) and tungsten (1b) have been synthesized by the direct reaction of bis(3,5-dimethylpyrazolyl)ethane (bmpze) with M(CO)₆ (M = Mo or W). The molecular structure (1b), determined by x-ray crystallography, showed the seven-membered ring W–N–N–C–C–N–N to be in the boat conformation. Upon treatment with RSnCl3 (R=Ph or Cl) in CH₂Cl₂ at room temperature, complexes (1a) and (1b) gave the seven-coordinate oxidative-addition products [(bmpze)M(CO)₃(SnCl₂R)Cl] [M = Mo, R = Ph, (2a); M = W, R=Ph, (2b); M = Mo, R = Cl, (2c); M = W, R = Cl, (2d)]. When complexes (1b) and (2b) were heated under reflux with 1,2-bis(diphenylphosphino)ethane (dppe), the ligand, bmpze, in these complexes was easily removed. The novel compounds were characterized by ¹H-n.m.r., i.r. and elemental analysis.     

Synthesis, characterization and crystal structure of bis(acetylacetonato)dichlorotin(IV)

The compound bis(acetylacetonato)dichlorotin(IV) [Sn(acac)₂Cl₂] forms a distorted octahedral structure involving both oxygen atoms of the acetylacetone group. The two chlorides occupy the cis position, with Sn-Cl distances of Sn1-Cl1 = 2.380(2) Å, Sn1-O1 = 2.043(2) Å and Sn1-O2 = 2.093(2) Å. We report here a new and simple method for the synthesis of Sn(acac)₂Cl₂, its spectroscopic characterization and, for the first time, we report its crystal structure.     

Pincer-type bis(carbene)-derived complexes of nickel(II): Synthesis, structure, and catalytic activity

Air- and moisture-stable NHC (N-heterocyclic carbene)-derived CNC-type pincer complexes of nickel(II) 4a-d were successfully synthesized, and their structures were fully characterized using X-ray crystallography and analytical and spectroscopic methods. These complexes exhibit a high catalytic activity for the Suzuki-Miyaura coupling reaction of aryl bromides and chlorides with aryl- and alkenylboronic acids, providing an array of biphenyls and stilbenes generally in high yields.     

Monoalkylthallium(III) derivatives: preparation and X-ray crystal structure of cyclopropylbis(isobutyrato)thallium(III)

Cyclopropylbis(isobutyrato)thallium(III) has been synthesised and its crystal structure determined. The compound crystallises in the orthorhombic space group Pna2₁, with a 7.316, b 12.079, c 16.19 Å. Linear polymers are present in which thallium is seven-coordinate. Two types of carboxylate ligands are present; one weakly chelating and the other both chelating and bridging.This structure allows clarification of infrared spectroscopic data, presented for mono- and diorganothallium(III) carboxylates, in the solid state in solution.