Studies on novel unsymmetrical azomethines—III : Copper(II) complexes of unsymmetrical tetradentate azomethines

Copper(II) complexes of unsymmetrical bifunctional tetradentate azomethines having the general formulae, (OC₁₀H₆CH:NXN:C(R)C₆H₄O)Cu, (OC₁₀H₆CH:NXN:C(CH₃)CHC(CH₃)OCu, (OC₆H₄CH:NXN:C(CH₃)C₆H₄O)Cu, (OC₆H₄C(R);NXN:C(CH₃)CHC(CH₃)O)Cu (where R = H or CH₃, X = (CH₂)₃, (CH₂)₄, (CH₂)₆ or -oC₆H₄) have been synthesized by the reactions of preformed mixed imine complexes of the type, CuLL′ (where L and L′ are two different imines such as 2-hydroxy-1-naphthaldimine, salicylaldimine, o-hydroxyacetophenonimine or acetylacetonimine) with diamines such as 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane or o-phenylenediamine. These complexes have been characterized by elemental analyses, TLC, conductance, magnetic measurements, IR and electronic spectra.     

Heteronuclear (WFe) and homonuclear (FeFE) μ-alkylidene complexes of transition metals from mononuclear terminal carbene complexes. crystal structures of {WFe[μ-η1, η3-C(OCH2CH3)(CHCHCH3](CO)8} and [fe2{μ-η2,η3-C[OCH2CH3[CHC(OCH2CH3)(CH3]}(CO)6

The reactions of mononuclear carbene complexes of W and Fe of the type CO)_mMC(OR)(CH_2nCHCR′″ (M  = FE, W; m = 4 and 5; n = 0, 2, 3; R′, R″ = C, CH₃, OEt) with Fe(CO)₅ have been studied. In all cases the reaction leads to new hetero (WFe) or homo (FeFe) μ-alkylidene complexes, the position of the double bond depending strongly on n.     

Telomerisation par catalyse redox—XIII. Synthese d'alcools fluores a partir des telomeres des acetates de vinyle et d'allyle avec des telogenes fluores

Telomerizations by redox catalysis of vinyl and allyl acetates with carbon tetrachloride, 1,1,1 trichlorotrifluoroethane and CCl₃(CF₂CFCl)_nCl were studied. Chemical transformation of these telomers by various ways leads to corresponding alcohols: RCCl₂CH₂CH₂OH and RCCl₂CH₂CHClCH₂OH with R = Cl, CF₃, Cl(CFClCF₂)_n.     

Molecular mechanics calculations for conformational energies and torional force constants in fluoro propenes and butenes

Experimental data on conformational energies of the molecules FH₂CHCCH₂, FH₂CFCCH₂, FH₂C(CH₃)C&.dbnd;CH₂ trans-FH₂CHCC(CH₃)H have been used to establish parameter values for the nonbonding atom ⋯ atom interaction F ⋯ C(sp²) within the Morse potential formulation. Torsional potentials have been calculated for the four molecules mentioned above and in addition for cis- and trans-FH₂CHCCHF, (FH₂C)₂CCH₂, cis-FH₂CHCCHCH₂F, CH₃FCHHCCH₂ and FH₂CCH₂HCCH₂. Calculated results have been compared with experimental values. Torsional force constants for the molecules have been obtained. A comparison between fluoro, chloro and bromo compounds is presented.     

Synthesis and structural elucidation of some new heterocyclic β-diketone derivatives of boron

Some new β-diketone derivatives of boron having the general formula B₂O(OAc)_4?n[OC(R)$\text{C:CON(Ph)N:C}$ CH₃]_n (where n = 1 or 2; R = CH₃, C₂H₅, C₆H₅ and p-ClC₆H₄) have been synthesised by the reactions of oxy-bis(diacetatoborane) and substituted pyrazolones, such as 4-acyl-3-methyl-1-phenyl-2-pyrazolin-5-ones (acyl = acetyl, propionyl, benzoyl and p-chlorobenzoyl) in dry toluene solution in 1:1 and 1:2 molar ratios. These derivatives have been characterised by elemental analysis, molecular weight measurements. Structures have been proposed on the basis of chemical reactions, IR, ¹H and ¹¹B NMR spectral studies.In the derivatives B₂O(OAc)₃[OC(R)$\text{C:CON(Ph)N:C}$ CH₃] two of the three acetate groups are unidentate and the third is bridged between two boron atoms along with BOB linkage. Whereas the derivatives B₂O(OAc)₂[OC(R)$\text{C:CON(Ph)N:C}$ CH₃]₂ are the mixture of geometrical isomers.     

The reactions of alkyltrimethylphosphinenickel complexes with isocyanides and alkynes

t-Butylisocyanide reacts with NiRCl(PMe₃)₂ (R  CH₃, Ia; R  CH₂SiMe₃, Ib) to give, successively, the products of mono- and di-insertion into the nickelcarbon bonds; with more than two equivalents of isocyanide, trimethylphosphine ligands are displaced. In contrast to related palladium reactions, cyclohexyl isocyanide gives mono-insertion products only, while benzyl isocyanide is polymerised. The reactions of diphenylacetylene with Ia and Ib in methanol give (Z) vinylnickel complexes, trans-Ni{C(Ph)C(Ph)R}Cl(PMe₃)₂, while from reaction in diethyl ether a precursor complex [NiMeCl(PMe₃)₂ · (PhCCPh)_0.5] can be isolated. On heating the (Z)-vinyl complexes come into thermodynamic equilibrium with their (E)-isomers. The vinyl complexes are stereochemically rigid and resistant to further insertion.     

Carbon-13 and proton NMR parameters of neopentyl-and trimethylsilylmethyl-thallium(III) derivatives and the x-ray crystal structure of bis(trimethylsilylmethyl)chlorothallium(III)

Carbon-13 and proton NMR spectra have been determined for organothallium (III) derivatives of the types RTlX₂ and R₂ TlX (R  (CH₃)₃CCH₂ or (CH₃)₃SiCH₂; X  Cl, Br or O₂CCH(CH₃)₂). The dependence of coupling of ¹³C and ¹H to thallium on the number and nature of R groups is discussed in terms of the Fermi contact mechanism for spinspin coupling.The crystal structure of [(CH₃)₃SiCH₂]₂ TlCl has been determined. The compound crystallises in the monoclinic space group P2₁/n, with a 10.618, b 24.492, c 6.017 Å, β 99.76°. The molecule is dimeric with each four-coordinate thallium atom bonded unequally to two bridging chlorine atoms. The CTlC angle is 168°.     

Diorganotin(IV) bis(O,O-alkylenedithiophosphates)

O,O-Alkylenedithiophosphates of diorganotin(IV) of the type R₂Sn[SP(S)O₂G]₂ (R = Me, Et, n-Bu, Ph; G = CH₂CMe₂CH₂, CMe₂CMe₂, CMe₂CH₂CHMe) have been synthesized by the reactions of diorganotin(IV) dichlorides with ammonium O,O-alkylenedithiophosphates or that of diorganotin(IV) oxides with O,O-alkylenedithiophosphoric acids in 1:2 molar ratio in benzene. These new complexes are white solids which are soluble in common organic solvents and are monomeric in refluxing benzene; and they have been characterized by elemental analysis and by different spectroscopic (IR, ¹H, ¹³C, ³¹P and ¹¹⁹Sn NMR) studies, on the basis of which a six coordinated octahedral structure has been suggested in solution.     

The molecular structure of chlorothiomethoxymethyl-bis(triphenylphosphine)palladium(II) methylenechloride solvate at −160°C

The precise molecular structure of [PdCl(CH₂SCH₃)(PPh₃)₂] has been determined from three-dimensional X-ray diffraction data collected at ?160°C. The CH₂Cl₂ solvated crystal ([PdCl(CH₂SCH₃)(PPh₃)₂ · CH₂Cl₂]) belongs to the monoclinic system, space group P2₁/n, with four formula units in a cell of dimensions: a 14.973(3), b 15.333(3), c 17.377(3) Å and β 115.77(1)° at ?160°C. The structure was solved by the conventional heavy atom method and refined by the least-squares procedure to R = 0.035 for observed reflections. The geometry around the palladium atom is square-planar. The phosphorus atoms of the two triphenylphosphine ligands are mutually trans. The CH₂SCH₃ group is bonded to the palladium atom only through the PdC σ-bond and the sulfur atom is not bonded to the metal atom (PdC(1) 2.061(3), SC(1) 1.796(3), SC(2) 1.817(5), Pd?S 2.973(1) Å, PdC(1)S 100.64(14)° and C(1)SC(2) 101.28(18)°). The structure is in contrast to that of [PdCl(CH₂SCH₃)(PPh₃)], in which both the carbon and sulfur atoms of the CH₂SCH₃ group are bonded to the palladium atom.     

Preparation de β-cetonitriles via l'acylation du cyanacetate de trimethylsilyle par les anhydrides mixtes.

β-ketonitriles R¹COCH₂CN and R¹COCH(R²)CN are respectively prepared from (CH₃)₃SiOCOCHLiCN or R²CHLiCN by acylation reaction with mixed anhydrides RCOOCO₂Et.     

A multinuclear NMR spectroscopy study of alkoxysilanes

¹⁷O, ²⁹Si, and ¹³C NMR spectra of more than 100 mono-, di-, tri- and tetra-alkoxysilanes R_4−nSi(OR′)_n; R = C_nH_2n+1, Ph, CH₂Cl, CH₂Br; R′ = C_nH_2n+1, CH₂Ph, CH₂CH₂Cl, CH₂CHCH₂, CH₂CCH, CH₂CF₃. (CH₂)₃Cl, (CH₂)₃CN have been studied.Linear relationships between the chemical shifts of ¹⁷O, ²⁹Si, ¹³C in alkoxysilanes and the inductive and steric constants of substituents R and R′ were observed. Different transmission of electronic effects along the SiO bond in various directions was revealed by means of ¹³C, ²⁹Si, ¹⁷O NMR spectroscopy and correlation analysis. The results are discussed in terms of (pd)_π-bonding between the oxygen and silicon atoms in compounds containing an SiO bond.     

Base catalysed oligomerization of vinyl monomers—II. Synthesis of model compounds: α-Methylene-glutaric acid derivatives

Terminally unsaturated dimers and co-dimers of vinyl monomers having the general formula CH₂CCCR were synthesized, where X = Y or X ≠ Y, X and Y being COO R or CN groups, RCH₃ or H. NMR and base catalyzed isomerization of the 1-olefins prepared is discussed.     

Strukturuntersuchungen an mono- und bis-alkoxy(triphenylsilyl)-carben-komplexen des rheniums

Steric and electronic influences on bond lengths and angles at the carbene carbon atoms of cis-Re₂(CO)₉C(OR)SiPh₃ (I: R = CH₃, II, R = C₂H₅) and cis,trans-Re₂(CO)₈[C(OEt)SiPh₃]₂ (III) are discussed based on their structural analyses. I (ReRe 305.2(1) pm; ReC(carbene) 209(2) pm) and II (two independent molecules; ReRe 305.0(3) and 305.2(4) pm; ReC (carbene) 208(5) and 210(5) pm) differ by the cis and trans positions of the alkyl groups at the partial C(carbene)O double bonds. The change in configuration affects the bond angles at the carbene carbon. In III the carbene ligands are bonded to different rhenium atoms; cis to one Re atom and trans to the other Re atom (ReRe bond 309.1(2) pm). The ReC(carbene length of the trans- carbene ligand is significantly shorter (185(3) pm) than that of the cis-carbene ligand (208(3) pm).     

Syntheses and structural aspects of rigid aryl- palladium(II) and -platinum(II) complexes. X-ray crystal structure of o,o′-bis[(dimethylamino)methyl]phenyl- platinum(II) bromide

The tridentate monoanionic ligand o,o′-(Me₂NCH₂)₂C₆H₃ (NCN′) has been used to synthesize novel aryl-palladium(II) and -platinum(II) complexes [PtR(NCN′)] and [MX(NCN′)] (M = Pt, Pd). Three synthetic procedures are described, namely: (i) reaction of the cationic complex [M(NCN′)(H₂O)]⁺ with KX or NaX to give [MX(NCN′)] (X = Cl, I, O₂CH, NCS, NO₂, NO₃); (ii) displacement reactions using AgX with [MBr(NCN′)] to give [MX(NCN′)] (X = CN, O₃SCF₃. O₂CMe, O₂CCF₃) and (iii) transmetallation reactions of [PtBr{C₆H₃(CH₂NMe₂)₂-o,o′}] with organolithium to give [PtR{C₆H₃(CH₂NMe₂)₂-o,o′}] (R = Ph, o-, m-, p-tolyl, CCPh, CC-p-tolyl). All complexes have been characterized by elemental analysis, and IR, ¹H and ¹³C NMR spectroscopy.An X-ray diffraction study has shown that [PtBr{C₆H₃(CH₂NMe₂)₂-o,o′}] (2) has a square-planar structure, in which the tridentate ligand is bonded via C(ipso) (PtC 1.90(1) Å), and two mutually trans-N donor atoms (PtN(1) 2.07(1), PtN(2) 2.09(1) Å). The fourth site trans to C(ipso) is occupied by bromine (PtBr 2.526(2) Å). The two chelate rings (NPtC(ipso) 82.9(5) and 81.5(5)°) are distinctly puckered, with the two NMe₂ groups on opposite sides of the aryl plane. The PtC bond in 2 is shorter than analogous bonds in other arylplatinum(II) complexes, as a result of (i) the rigid structure of the tridentate ligand and (ii) the presence of two hard N donor atoms trans to one another across the platinum centre.     

The rotational barrier in dimethyl acetylene and related molecules

The rotational barriers in dimethyl acetylene (CH₃CCCH₃), diamino acetylene (H₂NCCNH₂), dihydroxy acetylene (HOCCOH), methyl trifluoro methyl acetylene (CF₃CCCH₃), silyl methyl acetylene (SiH₃CCH₃), propene, cis and trans 2-butene and ethane were studied by ab initio molecular orbital methods using various basis sets. The eclipsed structure for dimethyl acetylene and its CF₃ and SiH₃ analogs was found to be the most stable, as has been inferred from experimental work, and the barrier height for these compounds has been predicted. The barriers in the OH and NH₂ substituted acetylenes, propene, butene and ethane were studied in order to more clearly understand the important influences in determining the barrier mechanism; specifically, the delocalized molecular orbital and Pauling VB model have been compared.     

Alkoxycarbene complexes of nickel(II)

Alkynylnickel complexes trans-C₆Cl₅Ni(PPhMe₂)₂CCR (IIIa, R  H; IIIb, R  Me; IIIc, R  Et; IIId, R  CH₂OH; IIIe, R  CH₂CH₂OH; IIIf, R  Ph; IIIg, R  C₆H₄OMe-p) have been prepared from trans-[C₆Cl₅Ni-(PPhMe₂)₂L]ClO₄ and monosubstituted acetylenes in the presence of triethylamine, and their reactions with alcohols in the presence of perchloric acid were studied. Complexes IIIa and IIIe afforded alkoxycarbene complexes trans-[C₆Cl₅Ni-(PPhMe₂)₂{C(OR′)Me}]ClO₄ (IVa, R′  Me; IVb, R′  Et; IVc, R′  n-Pr) or trans-C₆Cl₅Ni(PPhMe₂)₂{$\text{C(CH}{}_2\text{)}{}_3\text{O}$}]ClO₄(IVd), respectively, but IIIb either decomposed or afforded trans-C₆Cl₅Ni(PPhMe₂)₂CHC(OMe)Me, depending on the amount of acid used. Treatment of IVaIVd with amines resulted in deprotonation to give α-alkoxyvinyl complexes, trans-C₆Cl₅Ni(PPhMe₂)₂C(OR′)CH₂ (VIaVIc) or trans-C₆Cl₅Ni(PPhMe₂)₂$\text{CCHCH}{}_2\text{CH}{}_2\text{O}$ (VId), the reaction being reversible. A ¹H NMR study indicated: (i) that the carbene methyl and the vinyl protons IV or VI are D-exchangeable by MeOD without catalyst; (ii) that the basicity of VIa is comparable to those of amines; (iii) that the carbene complexes IVaIVc have two isomers due to hindered rotation about the C(carbene)O bond in solution, IVb existing in the Z-form in the solid state; (iv) that the rotationalbarriers (°G^≠) about the C(carbene)O bond in IVb and the NiC-(carbene) bond in IVd are 20 (or more) and 11.7 kcal/mol, respectively. These results are explained in term of double bond character of the carbene carbon and its surrounding atoms.     

Synthesis of ylideplatinum(II) complexes via α-functionalised alkylplatinum(II) intermediates and some comparative data on palladium(II) complexes; X-ray structure of trans-[Pt(CH2PEt3)I(PEt3)2]I

The reaction of [Pt(PEt₃)₃] with CH₂I₂ affords trans-[Pt(CH₂PEt₃)I(PEt₃)₂]I and is believed to proceed via the α-functionalised alkyl cis-[Pt(CH₂I)I(PEt₃)₂], because similar ylides are obtained from cis- or trans-[PT(CH₂X)(PPh₃)₂X] (XCl, Br, or I) with PR₃ (PEt₃, PBu₃ⁿ, PMePh₂, PEtPh₂, or PPh₃); cis-[Pd(CH₂I)-I(PPh₃)₂] does not react with excess PPh₃, but with PEt₃ yields trans-[Pd(CH₂PEt₃)I(PPh₃)₂]I; the X-ray structure of trans-[Pt(CH₂PEt₃)I(PEt₃)₂]I (current R = 0.045) shows PtP(1) 2.332(7), PtP(2) 2.341(8), PtC 2.08(2), and PtI 2.666(2) Å, and angles (a) C(1)PtI, P(1), P(2): 176.9(8), 91.6(6), 93.4(6), (b) IPtP(1), P(2): 87.1(2), 88.5(2), and (c) P(1)P(2), 166.8(3), and (d) PtC(1)P(3), 118(1)°.     

Electronic structure and geometry of the active centres in anionic polymerization of vinyl monomers

The charge distributions in the ions (CH₃CHR) and in the molecules CH₃CHRLi (RNO₂, CN, COOCH₃, C₆H₅, CHCH₂, H, NH₂ or OCH₃), modelling the active centres of the two extreme types in anionic polymerization, were calculated by the CNDO/2 method. The geometry of these compounds was partly optimized. Both the geometry and the charge distribution in anions were found to exhibit no strong dependence on R. This suggests that in free ion polymerization, the equality r₁r₂ = 1 holds. The active centres of the polarized bond type are fairly varied. Two reasons for their reactivity may exist: the polarity of their CLi bond and their geometry facilitating the insertion of a monomer. The electronic structure of the neutral molecules considered correlates with the low degree of association of the living chains.     

Additions electrophiles sur les esters acetyleniques et alleniques—IV : Addition des halogenes et des halogenures de sulfenyle sur le butyne-3 oate d'ethyle

Ethyl but-3-ynoate undergoes electrophilic additions of BrCl and of ICl to give CHXCClCH₂COOEt E (X = Br or I). The addition of sulfenyl halides RSY follows the opposite orientation and leads to CHYCSRCH₂COOEt E (Y = Cl or Br, R = Et or Ph). In the case of IBr, both CHICBrCH₂COOEt E and CHBrClCH₂;COOEt E are obtained.A mechanistic interprétation of these results is supported by both the orientation and the kinetic order of the addition: PhSCl reacts by an Ad_E2 process, whereas ICl addition involves a combination of Ad_E3 and Ad_E4 mechanisms.     

Bis(fluorbenzoyloxy)methylphosphanoxide

Bis(fluorbenzoyloxy)methyl phosphane oxides CH₃P(O)[OC(O)R]₂ [R = C₆H₄2F (1), C₆H₄3F (2), C₆H₄4F (3), C₆H₃2,6F₂ (4), C₆H2,3,5,6F₄ (5)] were prepared by treating silver salts of carboxylic acids AgOC(O)R with CH₃P(O)C?₂ (IR-, ¹H-, ¹⁹?F-and ³¹P{¹H}-NMR-data). The mixed anhydrides 1–5 show unusual thermal stability at room temperature. Stability against hydrolysis decreases with increasing number of fluorine-atoms. The reaction of R′P(O)C?₂ [R′ = CH₃, C₆H₅, (CH₃)₃C] with M^IOC(O)R_F [R_F = CF₃, C₂F₅, C₆F₅; M^I = Ag^I, Na^I T?^I] was investigated.