Experimental and theoretical investigations of lithium and magnesium derivatives of bis(tert-butylamido)cyclodiphosph(III/V)- and (V/V)azane mono- and ditellurides

Deprotonation of bis(tert-butylamido)cyclophosph(III/III)azane with organolithium or organomagnesium reagents followed by oxidation with elemental tellurium is a viable approach to the preparation of metal cyclodiphosphazane mono- and ditellurides. The reaction of the cyclodiphosph(III)azane [tBu(H)NP(mu-NtBu)2PN(H)tBu] (1) with elemental tellurium in boiling toluene affords the monotelluride [tBu(H)N(Te)P(mu-NtBu)2PN(H)tBu] (9). A similar reaction involving the magnesium salt Mg[tBuNP(mu-NtBu)2PNtBu](THF)2 (2) also yields a monotelluride Mg[tBuN(Te)P(mu-NtBu)2PNtBu]-(THF)2 (10). By contrast, reaction of the lithium salt Li2[tBuNP(mu-NtBu)2PNtBu](THF)2 (3) with tellurium results in double oxidation and the formation of the ditellurides Li2[tBuN(Te)P(mu-NtBu)2P(Te)NtBu](THF)4 (11) and Li2-[tBuN(Te)P(mu-NtBu)2P(Te)NtBu](tmeda)2 (12). Compounds 9-12 have been characterized by multinuclear (1H, 7Li, 13C, 31P, and 125Te) NMR, while 9, 10, and 12 have also been characterized by X-ray crystallography. The structure of 9 reveals a typical cis/endo, exo arrangement, with no intermolecular contacts to tellurium. The seco-heterocubic structure, observed in 2, is retained in 10, with the ligand chelating magnesium in an N,N',N"-manner. Unique coordination behavior is exhibited by the ditelluride 12, in which the dianionic ligand is attached to the two lithium centers in both Te,Te' and Te,N bonding modes. Multinuclear NMR data are consistent with retention of the solid-state structures of 9-12 in solution at low temperatures. The reactivity of cyclodiphosph(III/III)azanes toward chalcogens is rationalized by using theoretical calculations (semiempirical PM3 level of theory), which show an inverse correlation between the charge at the phosphorus center and the ease of oxidation.     

The formation of dimeric phosph(III)azane macrocycles [[P(mu-NtBu)]2.LL]2 [LL = organic spacer

The dimeric macrocycles [[P(mu-NtBu)]2.LL]2 [LL = OCH2C(Me)2CH2O (1), 2,6-(NH)2C5H3N (2), 1,2-(NH)2C6H4(3)] have been obtained by the reactions of the appropriate diols and diamines (LLH2) with the dimeric phosph(III)azane [ClP(mu-NtBu)]2. Under different conditions the reaction of 1,2-(NH2)2C6H4 with [ClP(mu-NtBu)]2 gives the monomer [[P(mu-NtBu)]2.[1,2-(NH)2C6H4]] (4) (instead of the dimer 3). Contrary to the literature, the results illustrate that the formation of dimeric macrocycles is common in these reactions and dependent among other factors on the steric demands and length of the organic spacer (LL) as well as the reaction conditions.     

Bis(1 degree-amino)cyclodistib(III)azanes: the first structural characterization of cis and trans isomers of a single cyclodipnict(III)azane

The dichlorocyclodistib(III)azane [ClSb(mu-NtBu)]2 (1) has been shown to exist as the cis isomer in the solid state. A series of bis(1 degree-amino)cyclodistib(III)azanes [R'NHSb(mu-NtBu)]2 (2, R' = tBu; 3, R' = Dipp; 4, R' = Dmp) has been prepared by the reaction of 1 with 2 equiv. of LiNHR'. On the basis of NMR solution spectra, all three derivatives are formed as a mixture of cis and trans isomers. In the case of 3, the structures of both the cis and trans isomers have been determined by X-ray crystallography; cis-3 adopts an endo, endo arrangement for the amido protons of the DippNH groups. Isomerization of trans-3 into cis-3 occurs slowly in solution. Deprotonation of 2 with 2 equiv. of nBuNa or trans-3 with nBuLi produces [Na2Sb2(mu-NtBu)4] (5) and [Li2Sb2(mu-NtBu)2(mu-NDipp)2] (6), whose solvated cubane structures were established by X-ray crystallography. In contrast, the reaction of cis-3 with 2 equiv. of nBuLi produces the tricyclic compound [Li2Sb(mu-NtBu)2(mu-NDipp)(mu-NHDipp)] (7).     

Steric control in the oligomerisation of phosphazane dimers; towards new phosphorus-nitrogen macrocycles

The reaction of [ClP(mu-NtBu)]2 (1) with H2O (1 : 2 equivalents) in the presence of excess Et3N gives the new chain compound [(mu-O)[P(mu-NtBu)2P(H)=O]2] (3), consisting of two P2N2 rings linked by a mu-O atom and terminating in P(V)(H)=O groups. A similar chain species is obtained from the reaction of the lithiate of [(tBuNH)P(mu-NtBu)2P(H)=O] (5) with [ClP(mu-NtBu)2P(NHtBu)] (2), the product being [(mu-O)[P(mu-NtBu)2P(NHtBu)]2] (6). Compounds 3 and 6 are the first examples of O-bridged chain phosphazanes and potential precursors to new phosphorus-nitrogen macrocycles. The syntheses and X-ray structures of 3, 5 and 6 are reported.     

Synthesis and structure of the Li13 cage [[[O-P(mu-NtBu)]2Li2]3(LiCl)6Li(Cl/OnBu)0.5(thf)7], containing a [O-P(mu-NtBu)]2(2-) dianion

The hydrolysis of [ClP(mu-NtBu)]2 with H2O-Et3N in thf, followed by in situ lithiation with nBuLi gives the Li13 cage [[[O-P(mu-NtBu)]2Li2]3(LiCl)6Li(Cl/OnBu)0.5(thf)7], containing a [O-P(mu-NtBu)]2(2-) dianion that is isoelectronic with ligands of the type [(RN)P(mu-NR)]2(2-).     

Synthesis and structure of the calixarene-like phosph(III)azane macrocycle [{P(mu-N(t)Bu)}2{1,5-(NH)2C10H6}]3

The reaction of [ClP(mu-NtBu)]2 with 1,5-diamino-naphthalene [1,5-(NH2)2C10H6] in Et3N-thf gives the trimeric macrocycle [{P(mu-NtBu)}2{1,5-(NH)2C10H6}]3(1); the X-ray structure of the toluene solvate 1.3toluene reveals a cone-shaped (calixarene-like) arrangement in which toluene guest molecules are trapped within the cavity.     

Selection of the cis and trans phosph(III)azane macrocycles [{P(mu-NtBu)}2(1-Y-2-NH-C6H4)]2(Y=O, S)

The 1 : 1 reactions of [ClP(mu-NtBu)]2 with the difunctional aromatic amines 1,2-1-YH-2-NH2-C6H4 in the presence of Et3N give the dimeric phosph(III)azane macrocycles [{P(mu-NtBu)2(1-Y-2-HN-C6H4)]2, predominantly as the cis isomer in the case of Y=O (1.cis) and as the trans isomer for Y=S (2.trans). Model M.O. calculations suggest that the selection of the cis and trans isomers is not thermodynamically controlled. The alternative isomers 1.trans and 2.cis are generated exclusively by the deprotonation of the model intermediates [(1-Y-2-NH2-C6H4)P(mu-NtBu)]2[Y=O (3), S (4)] with nBuLi followed by cyclisation with [ClP(mu-NtBu)]2. The solid-state structures of 1.cis/trans(50 : 50), 2.cis, 3 and 4 are reported.     

An equilibrium analysis of the aqueous H+-MoO4(2-)-(HP)O(3)2- and H+-MoO4(2-)-(HP)O(3)2--HPO4(2-) systems

The speciation in the phosphitomolybdate system, H+-MoO4(2-)-(HP)O(3)2-, has been determined from combined potentiometric and 31P NMR measurements in 0.600 M Na(Cl) medium at 298(1) K. Potentiometric titration data were collected in the ranges 2.5<-log[H+]<6.2, 40.0相似文献   

The folded, tetrameric phosph(III)azane macrocycle [(P(mu-NtBu))2(1,4-(NH)2C6H4)]4

The tetrameric macrocycle [(P(mu-NtBu))2(1,4-(NH)2C6H4)]4, obtained from the reaction of the phosphazane dimer [ClP(mu-NtBu)]2 with p-phenylenediamine, has an unusual folded conformation in the solid state and contains a roughly tetrahedral arrangement of endo N-H groups for the potential coordination of anions.     

Reductions by titanium(II) as catalyzed by titanium(IV)

The cobalt(III) complexes, [(NH3)5CoBr]2+ and [(NH3)5CoI]2+ are reduced by Ti(II) solutions containing Ti(IV), generating nearly linear (zero-order) profiles that become curved only during the last few percent of reaction. Other Co(III)-Ti(II) systems exhibit the usual exponential traces with rates proportional to [Co(III)]. Observed kinetics of the biphasic catalyzed Ti(II)-Co(III)Br and Ti(II)-Co(III)I reactions support the reaction sequence: [Ti(II)(H20)n]2+ + [Ti(IV)F5]- (k1)<==>(k -1) [Ti(II)(H2O)(n-1)]2+ + [(H2O)Ti(IV)F5]-, [Ti(II)(H2O)(n-1)]2+ + Co(III) (k2)--> Ti(III) + Co(II) with rates determined mainly by the slow Ti(IV)-Ti(II) ligand exchange (k1 = 9 x 10(-3) M(-1) s(-1) at 22 degrees C). Computer simulations of the catalyzed Ti(II)-Co(III) reaction in perchlorate-triflate media yield relative rates for reduction by the proposed active [Ti(II)(H2O)(n-1)]2+ intermediate; k(Br)/k(I) = 8.     

Stereoisomerism in polyoxometalates: structural and spectroscopic studies of bis(malate)-functionalized cluster systems

The tetrameric macrocycle [(P(mu-NtBu))2(1,4-(NH)2C6H4)]4, obtained from the reaction of the phosphazane dimer [ClP(mu-NtBu)]2 with p-phenylenediamine, has an unusual folded conformation in the solid state and contains a roughly tetrahedral arrangement of endo N-H groups for the potential coordination of anions.     

Synthesis and elaboration of the dinuclear iron-imide cluster core [Fe2(mu-NR)2]2+

The protolysis of mononuclear ferric amide precursors FeCl[N(SiMe3)2]2(THF) (1) or [FeCl2{N(SiMe3)2}2]- (2) by primary amines provides, under suitable conditions, an effective route to dinuclear weak-field ferric-imide clusters with [Fe2(mu-NR)2]2+ cores. In the synthesis of known arylimide clusters [Fe2(mu-NAr)2Cl4]2- (Ar = Ph, p-Tol, Mes) from 2, the counterion has a major effect on selectivity and yield, and the use of quaternary ammonium salts affords a substantial improvement over earlier, Li+-based chemistry. The new tert-butylimide core is obtained by protolysis of 1 with excess tBuNH2 to give crystalline cis-Fe2(mu-NtBu)2Cl2(NH2tBu)2 (9). Complex 9 can be transformed to other dinuclear species through substitution of the terminal amines by pyridines, PEt3, or chloride, or through protolysis of bridging alkylimides by arylamines, allowing isolation of trans-Fe2(mu-NtBu)2Cl2(DMAP)2 (DMAP = 4-dimethylaminopyridine), cis-Fe2(mu-NtBu)2Cl2(PEt3)2, [Fe2(mu-NtBu)2Cl4]-, and trans-Fe2(mu-NPh)2Cl2(NH2tBu)2. The susceptibility of alkyl substituents to beta-elimination appears to limit the general applicability of protolytic cluster assembly using alkylamines. The dinuclear clusters have been characterized by X-ray, spectroscopic, and electrochemical analyses.     

Mechanistic analysis of reductive nitrosylation on water-soluble cobalt(III)-porphyrins

The reactions of NO and/or NO2- with three water-soluble cobalt porphyrins [Co(III)(P)(H2O)2]n, where P = TPPS, TCPP, and TMPyP, were studied in detail. At pH < 3, the reaction with NO proceeds through a single reaction step. From the kinetic data and activation parameters, the [Co(III)(P)(NO)(H2O)]n complex is proposed to be the primary product of the reaction with NO. This complex reacts further with a second NO molecule through an inner-sphere electron-transfer reaction to generate the final product, [Co(III)(P)(NO-)](n-1). At pH > 3, although a single reaction step is also observed, a systematic study as a function of the NO and NO2- concentrations revealed that two reaction steps are operative. In the first, NO2- and NO compete to substitute coordinated water in [Co(III)(P)(H2O)2]n to yield [Co(III)(P)(NO)(H2O)]n and [Co(III)(P)(NO2-)(H2O)](n-1) as the primary reaction products. Only the nitrite complex could be detected and no final product formation was observed during the reaction. It is proposed that [Co(III)(P)(NO)(H2O)]n rapidly reacts with NO2- to form the nitrite complex, which in the second reaction step reacts with another NO molecule to generate the final product through an inner-sphere electron-transfer reaction. The reported results are relevant for the interaction of vitamin B(12a) with NO and NO2-.     

Direct C-arylation of free (NH)-indoles and pyrroles catalyzed by Ar-Rh(III) complexes assembled in situ

Ar-Rh(III) pivalate complexes assembled in situ from the reaction of [RhCl(coe)2]2 (coe = cis-cyclooctene), [p-(CF3)C6H4]3P, and CsOPiv effectively catalyzed the direct C-arylation of free (NH)-indoles and (NH)-pyrroles in good yields and with high regioselectivity. The reaction displayed excellent functional group compatibility and low moisture sensitivity. Kinetics studies support a mechanism involving phosphine displacement by indole in complex 2 (resting state of the catalyst), followed by a rate-limiting C-H bond metalation.     

Catalytic alkylation of aryl Grignard reagents by iron(III) amine-bis(phenolate) complexes

Reaction of n-propylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H(2)L1, n-propylamino-N,N-bis(2-methylene-4,6-di-tert-butylphenol), H(2)L2, and benzylamino-N,N-bis(2-methylene-4-tert-butyl-6-methylphenol), H(2)L3, with anhydrous ferric chloride in the presence of base yields the products, [FeL1(μ-Cl)](2) (1), [FeL2(μ-Cl)](2) (2) and [FeL3(μ-Cl)](2) (3). In the solid state, these complexes exist as chloride-bridged dimers giving distorted trigonal bipyramidal iron(III) ions. Reaction of H(2)L1 with FeBr(3), however, results in the formation of a tetrahedral iron(III) complex possessing two bromide ligands. The amine-bis(phenolate) ligand is bidentate in this complex and bonds to the iron(III) ion via the phenolate O-donors. The central amine donor is protonated, resulting in a quaternized ammonium fragment and the iron(III) centre possesses a negative formal charge. As a result, this complex is zwitterionic and formulated as FeBr(2)L1H (4). Complex 1 is an air-stable, non-hygroscopic, single-component catalyst for C-C cross-coupling of aryl Grignard reagents with primary and secondary alkyl halides, including chlorides. Good to excellent yields of cross-coupled products are obtained in diethyl ether at room temperature. In some cases where low yields are obtained under these conditions, the use of microwave-assisted heating of the reaction mixture can improve yields.     

Radical-ligand-derived C-N coupling, Ga(III)-radical vs low-spin Co(III)-radical reactivity

The redox-active ligand 2-(3,5-dimethoxyanilino)-4,6-di- tert-butylphenol, H 2L (OCH3), results in, as expected, a trisradical complex with a low-spin Co(III) center, [Co (III)(L (OCH3) (*)) 3] ( 1), whereas the Ga(III) center yields a coordinated new hexadentate monoradical ligand, [Ga (III)L (*) 1] ( 2), presumably due to the ligand-derived redox activity involving C-H activation.     

Selection of a pentameric host in the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5].I]-[Li(thf)4]+ and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF

The structures of the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5]I]-.[Li(thf)4]+ [2.I[Li(thf)4]] and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF (2.HBr.THF) show that increased distortion of the framework of the pentameric macrocycle [[[P(mu-NtBu)]2(mu-NH)]5] (2) occurs with the larger halide ions. Theoretical studies show that the thermodynamic stabilities of the model host-guest anions [2.X]- (X=Cl, Br, I) are in the order Cl- approximately Br->I-, that is, the reverse of the templating trend observed experimentally. These studies support the view that the selection of the pentamer 2 over the tetramer [[[P(mu-NtBu)]2(mu-NH)]4] (1) is kinetically controlled, a conclusion which is also consistent with the previous observation that the frameworks of 1 and 2 are not in dynamic equilibrium with each other.     

Effects of large halides on the structures of lanthanide(III) and plutonium(III) borates

Reactions of LnBr(3) or LnOI with molten boric acid result in formation of Ln[B(5)O(8)(OH)(H(2)O)(2)Br] (Ln = La-Pr), Nd(4)[B(18)O(25)(OH)(13)Br(3)], or Ln[B(5)O(8)(OH)(H(2)O)(2)I] (Ln = La-Nd). Reaction of PuOI with molten boric acid yields Pu[B(7)O(11)(OH)(H(2)O)(2)I]. The Ln(III) and Pu(III) centers in these compounds are found as nine-coordinate hula-hoop or 10-coordinate capped triangular cupola geometries where there are six approximately coplanar oxygen donors provided by triangular holes in the polyborate sheets. The borate sheets are connected into three-dimensional networks by additional BO(3) triangles and/or BO(4) tetrahedra that are roughly perpendicular to the layers. The room-temperature absorption spectrum of single crystals of Pu[B(7)O(11)(OH)(H(2)O)(2)I] shows characteristic f-f transitions for Pu(III) that are essentially indistinguishable from Pu(III) in other compounds with alternative ligands and different coordination environments.     

Structural comparisons of silver(I) complexes of third-generation ligands built from tridentate (o-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2)) versus bidentate poly(1-pyrazolyl)methane units (o-C(6)H(4)[CH(2)OCH(2)CH(pz)(2)](2)) (pz = pyrazolyl ring)

The new bitopic, bis(1-pyrazolyl)methane-based ligand o-C6H4[CH2OCH2CH(pz)2]2 (L2, pz = pyrazolyl ring) is prepared from the reaction of (pz)2CHCH2OH (obtained from the reduction of (pz)2CHCOOH with BH3.S(CH3)2) with NaH, followed by the addition of alpha,alpha'-dibromo-o-xylene. The reaction of L2 with AgPF6 or AgO3SCF3 yields {o-C6H4[CH2OCH2CH(pz)2]2(AgPF6)}n or {o-C6H4[CH2OCH2CH(pz)2]2(AgO3SCF3)}n, respectively. Both compounds in the solid state have tetrahedral silver(I) centers arranged in a 1D coordination polymer network. The analogous ligand based on tris(1-pyrazolyl)methane units, o-C6H4[CH2OCH2C(pz)3]2 (L3), reacts with AgO3SCF3 to form a similar coordination polymer, {o-C6H4[CH2OCH2C(pz)3]2(AgO3SCF3)}n. In this case, each tris(pyrazolyl)methane unit in L3 adopts the kappa2-kappa0 bonding mode. Crystallization of a 3:1 mixture of AgO3SCF3 and L3 yields {o-C6H4[CH2OCH2C(pz)3]2(AgO3SCF3)2}n, in which the tris(1-pyrazolyl)methane units adopt a kappa2-kappa1 coordination mode.     

Hydrothermal synthesis and magnetic properties of novel Mn(II) and Zn(II) materials with thiolato-carboxylate donor ligand frameworks

The hydrothermal reaction of thiosalicylic acid, (C(6)H(4)(CO(2)H)(SH)-1,2) with manganese(III) acetate leads to formation of the coordination solid [Mn(5)((C(6)H(4)(CO(2))(S)-1,2)(2))(4)(mu3-OH)2] (1) via a redox reaction, where resulting manganese(II) centres are coordinated by oxygen donor atoms and S-S disulfide bridge formation is simultaneously observed. Reaction of the same ligand under similar conditions with zinc(II) chloride yields the layered coordination solid [Zn(C(6)H(4)(CO(2))(S)-1,2)] (2). Hydrothermal treatment of manganese(III) acetate with 2-mercaptonicotinic acid, (NC(5)H(3)(SH)(CO(2)H)-2,3) was found to produce the 1-dimensional chain structure [Mn(2)((NC(5)H(3)(S)(CO(2))-2,3)(2))(2)(OH(2))(4)].4H(2)O (3) which also exhibits disulfide bridge formation and oxygen-only metal interactions. Compound 3 has been studied by thermogravimetric analysis and indicates sequential loss of lattice and coordinated water, prior to more comprehensive ligand fragmentation at elevated temperatures. The magnetic behaviour of 1 and 3 has been investigated and both exhibit antiferromagnetic interactions. The magnetic behaviour of 1 has been modelled as two corner-sharing isosceles triangles whilst 3 has been modelled as a 1-dimensional chain.