Transition metal (Group 6, Ru and Group 10) derivatives of aminophosphines, Ph2PN(H)R (R=Ph, C6H11)

The reactions of aminophosphines with Group 6 metal carbonyls afford both mono-substituted and disubstituted complexes. The reaction of Ph₂PN(H)C₆H₁₁ with molybdenum tetracarbonyl derivative gives a mixture of cis and trans-isomers. The reaction of Ph₂PN(H)Ph with Pd(COD)Cl₂ leads to the PN bond cleavage to give chloro bridged dimer, [Pd(PPh₂O)(PPh₂OH)(μ-Cl)]₂, whereas with Pt(COD)Cl₂, disubstituted cis-[PtCl₂{PPh₂N(H)R}₂]₂ was obtained. The reaction of Ph₂PN(H)C₆H₁₁ with RuCl₂(DMSO)₄ or RuCl₂(PPh₃)₃ leads to the formation of ionic complex, [RuCl{Ph₂PN(H)C₆H₁₁}₃]Cl.     

Synthesis and electrochemistry of Group 6 tetracarbonyl (N,N′-bis(ferrocenylmethylene)ethylenediamine)metal(0) complexes

Thermal substitution reaction of Cr(CO)₄(η^2:2-1,5-cyclooctadiene), Mo(CO)₄(η^2:2-norbornadiene), and W(CO)₅(η²-bis(trimethylsilyl)ethyne) with N,N′-bis(ferrocenylmethylene)ethylenediamine (bfeda) yields M(CO)₄(bfeda) complexes which could be isolated from the reaction solution and characterized by elemental analysis, MS, IR, and NMR spectroscopy. In the case of tungsten, W(CO)₅(bfeda) is formed as intermediate and then undergoes the ring closure reaction yielding the ultimate product W(CO)₄(bfeda). The electrochemical behavior of the M(CO)₄(bfeda) complexes was studied by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in dichloromethane with tetrabutylammonium tetrafluoroborate as electrolyte. Constant potential electrolysis of the complexes was performed successively at their peak potentials at 0 °C in their CH₂Cl₂ solution and the electrolysis was followed by in situ recording the electronic absorption spectra in every 5 mC. In the electrolysis of Cr(CO)₄(bfeda), the central Cr(0) is oxidized first and electrolysis continues with oxidations of two ferrocenyl groups until the end of totally three moles of electron passage per mole of complex. In the electrolysis of Mo(CO)₄(bfeda) and W(CO)₄(bfeda) the first oxidation occurs on the central atom forming a short-lived species which undergoes an intramolecular one-electron transfer and is reduced back to M(0) while one of the ferrocene units is oxidized to the ferrocenium cation at the same time. This indicates that the electron is transferred from iron to the central metal atom.     

Main Group and Group 11, 12, 2-pyridyl-(trimethylsilyl)methyl and -bis(trimethylsilyl)-methyl chemistry

Developments in the Main Group 1, 2, 13–15 and Groups 11 and 12 alkyl metal or metalloid chemistry of CH(SiMe₃)(2-pyridyl) (= r) and C(SiMe₃)₂(2-pyridyl) (= R) is reviewed along with observations on the closely related ligands, CH(SiMe₃)(6-methyl-2-pyridyl) (= rMe) and C(SiMe₃)₂(6-methyl-2-pyridyl) (= RMe).     

Synthesis,Characterization, and Symmetry Relations of the Crystal Structures of Some Bis(dioxane) Adducts of Group 1 / Group 13 Heterometallic Trifluoroacetates

Four bis(dioxane) adducts of mixed‐metal trifluoroacetates, M[M′(O₂CCF₃)₄(C₄H₈O₂)₂] (M = Na, K, Cs, M′ = In and M = Cs, M′ = Ga) were synthesized by reaction of alkali metal trifluoroacetate and group 13 element trifluoroacetate in 1,4‐dioxane and completely characterized including X‐ray structure determination. Geometric parameters, empirical bond valences and frequencies of the symmetric C=O stretching vibrations show that the moisture sensitive solids are composed of dimeric structural moieties with site symmetry 1 , containing alkali metal ions and bis(dioxane)tetrakis(trifluoroacetato)indate or ‐gallate ions. The dimeric units are further connected by weaker “intermolecular” dioxane interactions to neighboring alkali metal ions. Closer inspection of space group symmetry, unit cell parameters and atom sites allows to rationalize the compounds as members of two isotypic pairs that are further closely related due to the group‐subgroup relation of their monoclinc space groups to a common orthorhombic supergroup.     

Periodic patterns: the Group (n) and Group (n + 10) linkage

The early Periodic Tables displayed an 8-Group system. Though we now use an 18-Group array, the old versions were based on evidence of similarities between what we now label as Group (n) and the corresponding Group (n + 10). As part of a series on patterns in the Periodic Table, in this contribution, these similarities are explored for the first time in a systematic manner. Pourbaix (Eh–pH) diagrams have been found particularly useful in this context.     

Pentacarbonyl(2-ferrocenylpyridine)metal(0) complexes of Group 6 elements. Synthesis and characterization

2-Ferrocenylpyridine (2-Fcpy) was prepared according to the literature procedure. 1,1-Dipyridylferrocene was also obtained as a minor product and characterized by ¹H- and ¹³C-n.m.r. spectroscopy. Prolonged irradiation of Cr(CO)₆ in the presence of 2-Fcpy in n-hexane gave Cr(CO)₅(2-Fcpy) which could not be isolated due to its instability even at low temperature, but was detected in solution by i.r. spectroscopy. The preparation of Mo(CO)₆(2-Fcpy) from direct photolysis of Mo(CO)₅ with 2-Fcpy could not be achieved. However, the reaction of Mo(CO)₅ (THF) with 2-Fcpy gave Mo(CO)₅ (2-Fcpy) which was isolated and characterized by i.r., ¹H- and ¹³C-n.m.r. spectroscopic techniques. W(CO)₅ (2-Fcpy) was prepared by irradiation of W(CO)₆ in the presence of 2-Fcpy in n-hexane. The complex was isolated and characterized by i.r., ¹H-, ¹³C-n.m.r. spectroscopic techniques. W(CO)₅ (2-Fcpy) thus appears to be more stable than the Mo and Cr analogues. The main reason for the general instability of the M(CO)₅ (2-Fcpy) complexes is assigned to the weak -accepting ability of 2-ferrocenylpyridine.     

Efficient synthesis of (R)- and (S)-3-octanol, (R)-2-dodecanol, (R)-2-methyl-4-heptanol and (R)-2-methyl-4-octanol: the pheromones of Myrmica scabrinodis, Crematogaster castanea, C. liengmei, C. auberti and Metamasius hemipterus

A simple and efficient synthesis of optically active insect pheromones, such as (R)- and (S)-3-octanol, (R)-2-dodecanol, (R)-2-methyl-4-heptanol and (R)-2-methyl-4-octanol starting from non-racemic β-hydroxy sulfides has been established.     

Group 15 ligand migration in the heteronuclear clusters RuOs3(μ-H)2(CO)12(EPh3) (E = P, As, Sb)

The monosubstituted clusters RuOs₃(μ-H)₂(CO)₁₂(EPh₃) (where E = P, As, Sb) exhibit isomers in which the group 15 ligand is on an Os or an Ru vertex. Evidence is presented for hydride fluxionality and EPh₃ ligand migration. These processes have been examined by variable temperature NMR studies, and the kinetic parameters estimated.     

Synthesis of trifluoromethyl amines,CF3N(X)H,from CF3N(X)C(O)F.

A new general synthesis of trifluoromethyl amines of the type, CF₃N(X)H, is reported. The amines are prepared in excellent yield by the hydrolysis CF₃N(X)C(O)F in the presence of NaF. The N-acyl fluorides are now available in considerable variety from the reaction of nucleophiles with the oxaziridine CF₃$\text{NCF}{}_2\text{O}$. Six new amines have been prepared and characterized [(X=CF₃O, (CF₃)₂CFO, CH₃O, C₂H₅O, (CH₃)₂CHO and (CH₃)₃CO)] and improved syntheses of CF₃NHF and CF₃NHOC(O)CH₃ are reported. The new compounds are thermally stable at 22° and are characterized by IR, NMR and physical properties.     

The S(6) Point Group Conformers of the Hexamethylchalcogens: Me(6)S, Me(6)Se, Me(6)Te

The synthesis of Me(6)Te in 1990 stimulated the exploration of hexamethylchalcogen potential energy surfaces. This earlier ab initio work focused only on the D(3) conformers, but it has been noted that the pseudooctahedral X(CH(3))(6) compounds show either D(3) or S(6) symmetry. Here are reported the results of an ab initio molecular orbital study of the hexamethylchalcogens confined to S(6) symmetry. Stationary points were found for each of the three hexamethylchalcogens studied and were shown to be minima for the two larger hexamethylchalcogens. Each of the S(6) stationary points found was energetically higher lying than the earlier reported D(3) counterpart. These energy differences are discussed in terms of nuclear repulsion and molecular orbital bonding considerations.     

含偶氮苯聚芳亚胺的合成、表征和光谱分析

以4,4＇-二溴二苯甲酮和4,4＇-二氨基偶氮苯为单体,通过钯催化的胺基化反应缩聚合成了含偶氮苯基团的新型结构聚芳亚胺（PAI-A）．PAI-A结构通过FT—IR,^1H NMR和元素分析测定,测试结果和目标产物吻合良好．在不同的条件下测定了聚合物的光学性能．     

(p-Phenylazophenyl)-Isopropyloxycarbonyl,a New Protecting Group for Peptide Synthesis

The preparation and properties of thirty two N(α)-[2-(p-phenylazophenyl)-isopropylcarbonyl]-amino-acids and derivatives are described. The new coloured protecting group (AZOC-) can be easily and selectively removed with mild acid treatment, much the same as the 2-(biphenyl)-isopropyloxycarbonyl (BPOC-)group. It is introduced via quite stable and yet reactive, crystalline intermediates, AZOC-OPh and AZOC-N₃.