Reactions of N,N-dimethylamino(diphenylphosphoryl)chloromethane with alkan-2-ones

The direction of the reaction of N,N-dimethylamino(diphenylphosphoryl)chloromethane with alkan-2-ones depends on the ketone structure. N,N-Dimethylamino(diphenylphosphoryl)-chloromethane reacts with linear alkan-2-ones following the Abramov-type reaction to give α-phosphorylated alcohols, while the reaction with branched alkan-2-ones and acetophenone proceeds as the Mannich-type reaction affording the phosphorylated Mannich bases.     

Synthesis of peptide–cellulose conjugate mediated by a soluble cellulose derivative having β-Ala esters (II): conjugates with O-phospho-l-serine-containing peptides

A synthetic route is described here for novel peptide-cellulose conjugates containing O-phospho-l-serine. First, Boc-Ser(PO₃Ph₂) and the related dipeptides, Boc-Ser(PO₃Ph₂)-Asp(OBzl) and Boc-Asp(OBzl)-Ser(PO₃Ph₂), were synthesized by adopting the phosphoryl-protection strategy. The condensation reaction between the α-carboxyl group of the protected Boc-Ser(PO₃Ph₂) and the β-amino groups of β-Ala-Cellulose using isobutyl chloroformate and N-methylmorpholine yielded the product conjugate, N ^β -[Boc-Ser(PO₃Ph₂)]-β-Ala-Cellulose. The degree of substitution of Boc-Ser(PO₃Ph₂) towards the β-amino groups of β-Ala-Cellulose was estimated as DS ^N  = 0.75 (maximum, 1.0). Similar reactions between β-Ala-Cellulose and two kinds of protected dipeptides, Boc-Asp(OBzl)-Ser(PO₃Ph₂) and Boc-Ser(PO₃Ph₂)-Asp(OBzl), gave the corresponding conjugates, and the DS ^N was estimated to be 0.95 and 0.69, respectively. The phenyl, benzyl, and Boc groups were removed in one-pot using the Pt₂O catalyst in 50 % trifluoroacetic acid/acetic acid. The ³¹P-NMR and UV–Visible spectra indicated the complete deprotection without any observable elimination of the phosphorylated peptides.     

Organotin(IV) azido and mixed azidothiocyanato complex anions; A Mössbauer and vibrational spectroscopic study

Tetraphenylarsonium and tetramethylammonium salts of the complex anions Ph₃Sn(N₃)^?₂, Ph₃Sn(N₃)(NCS)^?, Me₂Sn(N₃)^2?₄ and Ph₂Sn(N₃)₂(NCS)^2?₂ have been synthesized, and the solid state configuration of the complex anions has been studied by Mössbauer and vibrational spectroscopies. Trigonal bipyramidal structures are advanced for the Ph₃Sn^IV derivatives, with equatorial SnC₃ and apical pseudohalide ligands, while the R₂Sn^IV compounds are assumed to be trans-octahedral species. The NCS^? ligands are observed to be N-bonded to Sn^IV. Conductance and PMR (for the Me₂Sn^IV compound) data suggest the presence of the complex anions also in solution phases.     

Coordination and extraction properties of new bis- and tetrakis(diphenylphosphoryl)-substituted pyrazines towards f-block elements

2,3-Bis- and 2,3,5,6-tetrakis(diphenylphosphoryl)-substituted pyrazines have been synthesized from the corresponding polychloropyrazines and ethyl diphenylphosphinite. They may serve as new N,O-bidentate organophosphorus ligands for extraction and recovery of f-block metal ions from nitric acid solutions.     

Phosphoryl transfer from phenyl and 4-nitrophenyl phosphates in aprotic and protic solvents : Amine catalysis and formation of oxyphosphorane and metaphosphate intermediates

The behavior of 4-nitrophenyl dihydrogen phosphate, ArOPO₃H₂, and of its tetra-n-butylammonium and tetramethylammonium salts, ArOPO₃H^?R₄N⁺, ArOPO₃^2?2(R₄N⁺), was studied in aprotic solvents, in the absence and in the presence of increasing amounts of alcohols or water. The reactions were investigated in the absence of amines, and in the presence of hindered and unhindered amines, diisopropylethylamine and quinuclidine. The course of the reactions was followed at 35° or at 70° by ³¹P and ¹H NMR spectrometry. Values for the approximate half-times of the reactions were estimated (± 25 %) from the times at which reactant signal intensity becomes equal to product signal intensity. The mononitrophenyl ester transfers its phosphoryl group to alcohols and water from the diprotonated acid by the addition-elimination mechanism via oxyphosphorane intermediates, and from the monoanion and dianion by the elimination-addition mechanism via the monomeric metaphosphate intermediate, PO₃^?. Formation of PO₃^? is faster from dianion than from monoanion in acetonitrile and in alcohol solutions. Conversely, PO₃^? is generated at a faster rate from monoanion than from dianion in aqueous solution. This effect results from a decrease in the rate of formation of PO₃^? in the solvent series: acetonitrile > alcohols > water. The rate depression as a function of the medium is greater for the dianion than for the monoanion, and is attributed to greater solvation of the more polar phosphate ground state than of the less polar transition state in the more polar protic solvents. Unhindered amines add to 4-nitrophenyl phosphate monoanion, but not to the dianion. The oxyphosphorane intermediate thus formed collapses to aroxide ion and a protonated dipolar phosphoramide which is rapidly deprotonated by the relatively basic 4-nitrophenoxide: ArOPO₃H^? + CH(CH₂CH₂)₃N(acetonitrile ? CH(CH₂CH₂)₃N⁺P(O)(OH)O^? + ArO^?? CH(CH₂ CH₂)₃N⁺PO₃^2?+ ArOH → CH(CH₂CH₂)₃N + PO₃^?. The postulated formation of PO₃^? by this route explains why the addition of quinuclidine to an acetonitrile solution containing the monoanion salt, ArOPO₃H^?R₄N⁺, and t?BuOH produces t-butyl phosphate at a faster rate than the addition of diisopropylethylamine to the same solution. 2,4-Dinitrophenyl phosphate, which was previously studied by the same techniques, reacts via oxyphosphorane intermediates from the diprotonated and the monoanion forms, and via monomeric metaphosphate, from the dianion form.     

Effect of solvent and remote ligand substituents on the photochemical behaviour of copper(II) dithiocarbamates and dithiophosphates

The photochemical properties of bis(dithiocarbamato)Cu^II, Cu(R¹dtc)₂, and bis(dithiophosphato)Cu^II, Cu(R₂ ²dtp)₂, complexes with different remote ligand substituents (R¹ = piperidine, morpholine, pyrrolidine and 4-phenylpiperazine; R² = Me, Et and i-Pr) have been studied in chloromethanes (CCl₄, CHCl₃, CH₂Cl₂), chloromethanes/EtOH and PhMe. The monomeric species Cu^II(R¹dtc)Cl and its chloride-bridged dimeric form Cu₂(R¹dtc)₂Cl₂ were subsequently obtained during Cu(R¹dtc)₂ photolysis in chloromethane/EtOH mixtures and the steady-state concentration of Cu₂(R¹dtc)₂Cl₂ was found to depend on the EtOH content in the mixed solvents as well as on the nature of R¹ and the oxidising ability of the chloromethane. The appearance of the mixed-ligand complex Cu^II(R₂ ²dtp)Cl has been observed as an intermediate photoproduct after longer u.v.-irradiation of Cu(R₂ ²dtp)₂ in chloromethanes/EtOH.     

Can the pentazole anion (N5−) be isolated and/or trapped in metal complexes?

The 1,3-dipolar cycloreversion pathway of the pentazole anion (N₅^?) to the azide anion (N₃^?) plus dinitrogen (N₂) has been investigated using ab initio methods. At the MP4SDQ/6–31 + G* level of theory plus zero-point energy contributions, the pentazole anion is predicted to lie at 31 kcal mol^?1 above the N₃^? + N₂ system but the energy barrier for decomposition is 22 kcal mol^?1. This indicates that the pentazole anion could be isolated in an inert matrix at low temperature. Comparison between extended Hückel calculations on the (N₅)M(CO)₃ and (C₅H₅)M(CO)₃ complexes (with M = Fe²⁺, Mn⁺ and Cr) suggests that the N₅^? complexes would be formed if the fragments could be brought together. Predicted vibrational frequencies of the N₅^? anion are also reported.     

ELECTRON-TRANSFER PROCESSES. PART 40. REACTION OF ALKYL RADICALS WITH DIPHENYLPHOSPHIDE ANION

Abstract

The anion Ph₂P^? (K⁺, 18-crown-6) reacts with t-BuHgCl in HMPA to form Ph₂PCMe₃ by a free radical chain mechanism. In Me₂SO, Ph₂P(O)CMe₃ is produced. Reaction of Ph₂P^? with PhCOCH₂HgCl yields the oxidative dimerization product isolable from HMPA but readily converted to Ph₂P(O)P(O)Ph₂ in Me₂SO.     

A novel C3v-symmetric molecular clip with tris(diamide) recognition sites on trindane platform for H2PO4− recognition

To avoid the deprotonation events occurred in the receptor upon recognition of basic anions, a novel C_3v-symmetric anion receptor 2 with two amide groups appended in each arm was designed and synthesized by using the trindane tricarboxylic acid as tripodal molecular framework. The anion recognition ability by 2 was examined by ¹H NMR titration study in DMSO-d₆, which revealed that the addition of H₂PO₄^? guests caused substantial downfield shifts of the amide-NH protons peaks due to the formation of a host-guest complex in 1:1 binding stoichiometry with the estimated binding constant (K_a) of 244?M^?1. No noticeable binding of 2 was observed with other tested anions such as F^?, Cl^?, Br^?, I^?, NO₃^? and HSO₄^? under similar conditions.     

Coordination properties of the multifunctional S,N,S zwitterionic ligand EtNHC(S)Ph2PNPPh2C(S)NEt

The reaction of trialkylphoshanes and amino-phosphanes with isothiocyanates yields adducts containing the zwitterionic thioamidyl-phosphonium P⁺C(S)N^? functional group. Ligands containing this group were not previously studied, probably due to their instability towards dissociation, in the presence of metal species able to coordinate the P atom. The ligand EtNHC(S)Ph₂PNPPh₂C(S)NEt (HEtSNS) was obtained by reaction of Ph₂PNHPPh₂ with ethylisothiocyanate and proved to be very versatile: it can be protonated giving cation H₂EtSNS⁺ and deprotonated forming the dianion–cation EtSNS^?. HEtSNS and its derivatives behave as ligands showing five possible coordination fashions, S,N,S tridentate and S,S-bidentate (with a bite-angle varying from 180° to 90°), S-monodentate, S,S bridging and N,N,N interaction. Here we describe the coordination chemistry of HEtSNS, in particular towards Rh, Cu, Ag and Au, and some properties of its complexes which are still the only examples containing the P⁺C(S)N^? zwitterionic group.     

Anion coordination complex [Cl⊂Pt(bpt)<Subscript>4</Subscript>]Cl (bpt=<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-bis(3-pyridylmethyl)-2-thiourea)

The anion coordination complex, [Cl?Pt(bpt)₄]Cl (bpt=N,N′-bis(3-pyridylmethyl)-2-thiourea), was synthesized and studied by X-ray crystal structure analysis, NMR and FAB mass spectra. In the solid state, the Pt(bpt)₄ anion receptor adopts a cone conformation to bind the chloride anion through hydrogen bonds and electrostatic interaction in which the four branches of the thiourea ligands bind the chloride anion to form N-H?Cl^? hydrogen bonds (3.49–3.81 Å). The entraped chloride anion is situated above the Pt(II) center at 3.52 Å. Further second-sphere coordination assemby from the Pt(bpt)₄ core with 8 zinc(II) tetraphenylporphyrins (ZnPr) is discussed.     

Polymerizations of ethylenic monomers initiated by superacids—II: Complexation of some trifluoromethanesulphonates by their conjugate acid

Ionic trifluoromethanesulphonates (triflates) are strongly solvated with their conjugate acid in dichloromethane (Ph₃C⁺, n-Bu₄N⁺, Ag⁺) and acetonitrile (Na⁺, Ag⁺). A ¹H and ¹⁹F NMR study of the chemical shifts of various acid-salt mixtures show that in CH₂Cl₂ three homoconjugates A^? · HA, A^?. (HA)₂ and A^?(HA)₃ were formed with large formation constants whereas in acctonitrile only the 1:1 homoconjugate was formed with an equilibrium constant K₁ ～ 4 1 · M^?1. This result explains why the protonation by CF₃SO₃H of non-polymerizable olefins such as 1,1-diphenylethylene and 3-phenylindene is always incomplete ($\text{1}\text{3}$ and $\text{1}\text{2}$ respectively) in CH₂Cl₂. Conditions in which covalent triflates could be obtained have been investigated. As a consequence of homoconjugation, reaction of Ph₃COH with triflic anhydride led to Ph₃C⁺ CF₃SO^?₃ HOSO₂CF₃. Other tertiary alcohols were dehydrated by triflic anhydride and led to ethylenic compounds (1,1-diphenylethanol) or ethers (2-phenyl 2-propanol). Esters were only observed in the case of benzyltriflate (at ?20°) and in the case of 1-phenylethyltriflate which is a model of polystyryltriflate (stable at room temperature).     

A scheme of the stepwise reaction of diphenylchlorophosphine with <Emphasis Type="Italic">N,N</Emphasis>-dialkylformamides in the presence of NaI

On an example of DMF was proposed and experimentally verified stepwise reaction scheme of the reaction of diphenylchlorophosphine with N,N-dialkylformamides. The first stage is autocatalytic reaction of the synthesis of (diphenylphosphoryl)(N,N-dialkylamino)chloromethanes proceeding through the intermediate formation of diphenyldichloro[(N,N-dialkylamino)chloromethyl]phosphoranes. In the second stage that includes NaI, the (diphenylphosphoryl)(N,N-dialkylamino)chloromethanes are reduced by diphenyliodophosphine (or triphenylphosphine) to form the final N,N-dialkyl(diphenylphosphinomethylene)iminium iodides. One can assume that the reaction of the synthesis of N,N-dialkyl(diphenylphosphinomethylene)-iminium iodides proceeds in a similar way, starting with diphenyliodphosphine.     

Cleavage of a PN Bond in a Urea‐Containing (Ph2P(R)PPh2)‐Bridged Dinuclear Gold(I) Thiolate Complex by Fluoride and a Mechanistic Insight

A urea‐containing, (Ph₂P(R)PPh₂)‐bridged, dinuclear, gold(I) thiolate complex, [Au₂{Ph₂PN(C₆H₄OMe‐4)PPh₂}(SC₆H₄NHCONHC₆H₅)₂] ( 1 ) was designed and synthesized and its photophysical and anion recognition properties studied. The results show that 1 has a high selectivity toward F^?. Upon addition of F^?, the yellow solution was decolorized, and drastic changes of emission and ¹H and ³¹P{¹H} NMR signals were observed. Interestingly, these changes are attributed to fluoride‐assisted P?N bond hydrolysis, instead of the expected hydrogen‐bonding interactions with the urea receptor. Similar changes were observed for two other basic anions, AcO^? and H₂PO₄^?, but to a much lesser extent; and these anions were found to bind to the urea receptor at the same time. On the other hand, Cl^? was found to only bind to the urea moiety through hydrogen‐bonding interactions. Further studies with the control complex [Au₂{Ph₂PN(C₆H₄OMe‐4)PPh₂}Cl₂] ( 2 ) indicate that F^? assists the hydrolysis process via cleavage of the P?N bond. DFT calculations were performed to study the reaction mechanism for the fluoride‐assisted P?N bond hydrolysis of 2 ; these provide a better insight into the role of fluoride in the hydrolysis.     

Synthesis and cleavage reactions of thiocarbonyl-bridged Cp2Fe2(CO)3CS,and preparation of the carbene complexes CpFe(CO)C(N2C2H6)SnPh3 and [CpFe(CO)2C(OMe)2]PF6

The thiocarbonyl-bridged complex Cp₂Fe₂(CO)₃CS is obtained by the reaction of CpFe(CO)₂^? and (PhO)₂CS in THF. Infrared and NMR spectra show that the compound exists in solution in interconverting cis and trans forms, but that the isomerization occurs more slowly than for the carbonyl analog [CpFe(CO)₂]₂. Most reagents which cleave [CpFe(CO)₂]₂, such as Br₂, HgCl₂, and O₂/HBF₄, do not give simple cleavage reactions with Cp₂Fe₂(CO)₃CS. Reductive cleavage of Cp₂Fe₂(CO)₃CS with Na(Hg) gives the thiocarbonyl anion CpFe(CO)(CS)^?, which reacts with Ph₃SnCl to form CpFe(CO)(CS)SnPh₃. Methylamine reacts with CpFe(CO)(CS)SnPh₃ to give CpFe(CO)(CNMe)SnPh₃, while ethylenediamine gives the carbene complexes CpFe(CO)C(N₂C₂H₆)SnPh₃. The preparation of another new carbene complex, [CpFe(CO)₂C(OMe)₂]PF₆, is also described.     

Effect of anions on the dissolution of Al in acid solutions

The effect of Cl^?, Br^?, I^?, ClO₄^?, NO₃^?, HSO₄^?, HCrO₄^? and H₂PO₄^? on the of Al in 2 M HCl is studied by the thermometric method. Three sets of experiments are carried out, which allow the variation of the concentration of the various species in a programmed manner. Dissolution promotion is noted in solutions to which HCl, HBr and H₂CrO₄ are added. The way of action of each of these anions is discussed. Additions of HI, HClO₄, H₂SO₄ and H₃PO₄, on the other hand, first retard and later enhance the dissolution of Al in 2 M HCl, as their concentration in solution is increased. This is related to anion adsorption, which is counterbalanced by increase in acidity. HNO₃ differs from the other tested acids in causing only dissolution retardation. Experiments in which LaCl₃ is added to the test solution indicate that the NO₃^? is adsorbed as such on Al₂O₃. The ability of the various anions to retard the dissolution of Al in 2 M HCl decreases in the succession: NO₃^? (strong)>I^?>HSO₄^?>H₂PO₄^?>Br^?, ClO₄^? (weak)     

One-step synthesis of pentavalent triphenylantimony derivatives Ph3Sb(OSiR3)2, Ph3Sb(OCH2CH2)2NH and Ph3Sb(OCH2CH2NMe2)2: X-ray molecular structure of Ph3Sb(OSiMe3)2

Pentavalent bis(triorganosiloxy)triphenylantimony derivatives, Ph₃Sb(OSiR₃)₂ (R = Me, Ph), were synthesized by reaction of triphenylantimony with trimethyl- or triphenylsilanol in the presence of tert-butylhydroperoxide by the mild reaction conditions (0-5 °C, 2 h). The reaction of triphenylantimony with diethanolamine in the presence of tert-butylhydroperoxide gave the cyclic compound Ph₃Sb(OCH₂CH₂)₂NH. The mixture of Ph₃SbO and Ph₃Sb(OCH₂CH₂NMe₂)₂ was obtained by the reaction of triphenylantimony with 2-(N,N-dimethylamino)ethanol in the presence of tert-butylhydroperoxide.     

Heat of formation of Benzophenone Oxide

The heat of formation of benzophenone oxide, Ph₂CO₂, was measured using photoacoustic calorimetry. The enthalpy of the reaction Ph₂CN₂ + O₂ → Ph₂CO₂ + N₂ was found to be ?48.0 ±0.8 kcal mol^?1 and ΔH_f(Ph₂CN₂) was determined by measuring the reaction enthalpy for Ph₂CN₂ + EtOH → Ph₂CHOEt + N₂ (?53.6 ±1.0 kcal mol^?1). Taking ΔH_f(PhCHOEt) = ?10.6 kcal mol^?1 led to ΔH_f(Ph₂CN₂) = 99.2 ± 1.5 kcal mol^?1 and hence to ΔH_f(Ph₂CO₂) = 51.1 ± 2.0 kcal mol^?1. The results imply that the self-reaction of benzophenone oxide i.e., 2Ph₂CO₂ → 2Ph₂CO + O₂ is exothermic by ?76.0 ±4.0 kcal mol^?1.     

Metall-Schwefelstickstoff-Verbindungen. 22. S4N3Cl als Ausgangsprodukt zur Herstellung von Komplexen mit dem S3N−-Liganden Die Komplexe [Ph6P2N][Cu3(S3N)2(CN)2]und [Ph4As][(CuS3N)2(CN)]

The reaction of S₄N₃Cl with metal salts leads to complexes containing the S₃N^?chelating ligand, a reaction which proceeds smoothly especially in an alkaline medium. Thus we were able to prepare, by the reaction of CuCN with S₄N₃Cl and [Ph₆P₂N]OH (Ph = phenyl), the salt [Ph₆P₂N][Cu₃(S₃N)₂(CN)₂], a compound in which the anions build a bidimensional network through supplementary Cu - S contact interactions. The salt is monoclinic, space group C2/c, a = 18.960, b = 14.651 and c = 15.400 Å, β = 101.03° and Z = 4. Metal Sulfur Nitrogen Compounds. 22. S₄N₃Cl as a Starting Compound for the Preparation of Complexes Containing the S₃N^? Ligand. Complexes [Ph₆P₂N] [Cu₃(S₃N)₂ (CN)₂] and [Ph₄As] [(CuS₃N)₂ (CN)] In contrast, the reaction of CuN with S₄N₃Cl and [Ph₄As]OH led to the compound [Ph₄As][(CuS₃N)₂(CN)], monoclinic, space group C2/c, a = 18.478, b = 6.405, c = 27.051 Å, β = 119.50°, Z = 4. In the centrosymmetric anion the two Cu(S₃N) groups are linked together by disordered CN^? groups. An additional linkage results from Cu - Cu contact interactions, with d = 2.84 Å.     

The Preparation and X-Ray Structure of [AsPh4][Ph2P(S)NSiMe3] · 0.5 THF

The reaction of Ph₂P(S)N(SiMe₃)₂ with potassium tert-butoxide in a 1:1 molar ratio produces K[Ph₂P(S)NSiMe₃], which was converted to the AsPh₄⁺ salt by metathesis with [AsPh₄]Cl. The X-ray crystal structure of [AsPh₄][Ph₂P(S)NSiMe₃] · 0.5 THF consists of noninteracting AsPh₄⁺ and Ph₂P(S)NSiMe₃^? ions with d(P? S) = 1.980(4) Å and d(P? N) = 1.555(8) Å. The PNSi bite angle in the anion is 136.3(5)°. Electrophilic attack by Ph₂P(S)Cl occurs at the sulfur atom of Ph₂P(S)NSiMe₃^?. The oxidation of the anion with iodine produces a disulfide which regenerates K[Ph₂P(S)NSiMe₂] upon treatment with potassium tert-butoxide.