Synthesis and Reactivity of Dipalladated Derivatives of Terephthalaldehyde.

The polynuclear complex [{μ-1,4,,″-CH{C(H)=N(Bu)}-2,5}{Pd(μ-OAc)}] () reacts with tbbpy (4,4'-di--butyl-2,2'-bipyridine) and TlOTf to form the dinuclear complex [{μ-1,4,,″-CH{C(H)=N(Bu)}-2,5}{Pd(tbbpy)}] (). The hydrolysis of with acetic acid in a 5:1 acetone/water mixture, in the presence of two equivalents of tbbpy and excess NaX (X = Br, I), yields the dipalladated terephthalaldehyde complexes [CH{PdX(tbbpy)}-1,4-(CHO)-2,5] [X = Br (), X = I ()], which are the first fully characterized complexes of this type. The reaction of with CO results in the insertion of CO into both aryl-Pd bonds, forming [CH{C(O){PdX(tbbpy)}}-1,4-(CHO)-2,5] [X = Br (), X = I ()], which are the first examples of complexes with CO inserted into two separate aryl-metal bonds involving the same ligand.

Synthesis of mono-, di- and tripalladated 1,3,5-benzenetristyryl complexes. CO insertion to give a dipalladated indenone.

The tribrominated arenes 1,3,5-C(-CHCHAr)Br (Ar = Ph, (I), -To (I')), add oxidatively to [Pd(dba)] ([Pd(dba)]·dba) in the presence of two equivalents of a phosphine (PPh or PMePh) to form the monopalladated complexes -[Pd{C(-CHCHAr)Br}Br(L)] (Ar = Ph, L = PPh (1a), Ar = -To, L = PPh (1a'), Ar = Ph, L = PMePh (1b)), while the reaction in a 1 : 2 : 4 arene : Pd : PMePh molar ratio affords the dipalladated complex [{-PdBr(PMePh)}{μ-C(-CHCHPh)Br}] (2b). Both I and I' add oxidatively to 3 equivalents of [Pd(dba)] in the presence of the chelating N-donor ligand tmeda (,,','-tetramethylethylenediamine) to form the tripalladated complexes [{PdBr(tmeda)}{μ-C(-CHCHAr)}] (Ar = Ph, (3c), -To (3c')). Complex 3c reacts with PMe to form [{-PdBr(PMe)}{μ-C(-CHCHPh)}] (3d).

C-H Activation in Primary 3-Phenylpropylamines: Synthesis of Seven-Membered Palladacycles through Orthometalation. Stoichiometric Preparation of Benzazepinones and Catalytic Synthesis of Ureas.

The dimeric cyclometalated complexes [Pd2{κ(2)C,N-C6H4CH2CH2C(R)(Me)NH2-2}2(μ-Cl)2] (R = Me (1a), H (1b)) are prepared by reacting 1,1-dimethyl-3-phenylpropylammonium or 1-methyl-3-phenylpropylammonium triflate with Pd(OAc)2 in a 1:1 molar ratio and subsequent treatment with excess NaCl. The mononuclear derivatives [Pd{κ(2)C,N-C6H4CH2CH2C(R)(Me)NH2-2}Cl(L)] (L = PPh3, R = Me (3a), H (3b); L = 4-picoline (4-pic), R = Me (4a), H (4b)) were prepared from 1a,b by splitting the chloro bridges with the neutral ligands L. A conformational analysis of the mononuclear palladacycles in solution has been carried out.

Reactivity towards nitriles, cyanamides, and carbodiimides of palladium complexes derived from benzyl alcohol. Synthesis of a mixed Pd2Ag complex.

The chelate complex [Pd(κ(2)-C,O-C6H4CH2O-2)(bpy)] () reacts with acetonitrile, cyanamides, or carbodiimides, in the presence of AgOTf (1 : 5 : 1 molar ratio) and residual water, to form complexes [Pd{κ(2)-C,N-C6H4{CH2OC([double bond, length as m-dash]NX)Y}-2}(bpy)](OTf), where X = H, Y = Me (), NMe2 (), NEt2 (), X = R, Y = NHR (R = (i)Pr (), Tol ()), as a result of the insertion of the unsaturated reagent into the O-Pd bond of and the protonation of one of the N atoms. In the absence of AgOTf the reaction of with TolN[double bond, length as m-dash]C[double bond, length as m-dash]NTol (Tol = p-Tolyl) results in the formation of the neutral complex [Pd{κ(2)-C,N-C6H4{CH2OC([double bond, length as m-dash]NTol)NTol}-2}(bpy)] (). Complexes and can be interconverted by deprotonation ( + KO(t)Bu) or protonation ( + KOTf + HOTf) reactions.

Synthesis of Pd3Tl and Pd6Tl2 complexes based on a trinuclear aryl-palladium(II) complex acting as a metallaligand toward thallium(I) through Tl-arene and Tl-I bonds.

The metallaligand [(PdIL(2))(3)(C(6)Me(3)-1,3,5)] (L(2) = 4,4'-di-tert-butyl-2-2'-bipyridine = tbbpy) reacts with TlOTf to afford the complex [{(PdIL(2))(3)C(6)Me(3)-1,3,5}Tl]OTf, which exists in the solid state as a 2:1 mixture of monomer and dimer, both showing Tl(I)-I and Tl(I)-η(6)-mesitylene bonds. In solution, only the monomer is observed. Heating of toluene solutions of [(PdIL(2))(3)(C(6)Me(3)-1,3,5)] affords the dinuclear complex [(PdIL(2))(2)(C(6)HMe(3)-1,3,5)].

2-(Aminomethyl)phenyl complexes of Au(III), mixed Au(III)/Ag(I), and Pd(II) with the 2,2-diacetyl-1,1-ethylenedithiolato ligand: dancing of palladacycles around a juggler ligand.

The reaction of [Tl(2){mu-S,S-S(2)C=C{C(O)Me}(2)}] with [Au(C,N-C(6)H(4)CH(2)NMe(2)-2)Cl(2)] (1:1) gives [{Au(C,N-C(6)H(4)CH(2)NMe(2)-2)}{S,S-S(2)C=C{C(O)Me}(2)}] (1) which, in turn, reacts with AgClO(4) (1:1) to give [{Au(C,N-C(6)H(4)CH(2)NMe(2)-2)}{Ag(OClO(3))}{S(2)C=C{C(O)Me}(2)}] (2). Complexes [{Au(C,N-C(6)H(4)CH(2)NMe(2)-2)}{Ag(X)(PPh(3))}{S(2)C=C{C(O)Me}(2)}] [X = OClO(3) (3), ONO(2) (4)] have been obtained by reaction of 1 with PPh(3) and AgClO(4) or AgNO(3), respectively (1:1:1). Complex 3 can also be obtained by reacting 2 with PPh(3) (1:1).

Dancing of palladacycles around a "juggler" 2,2-diacetyl-1,1-ethylenedithiolato ligand in a trinuclear Pd(II) complex.

A trinuclear Pd complex containing a mu3-1,1-ethylenedithiolato ligand has been synthesized and its structure confirmed by X-ray crystallography. It is the first example of a 1,1-ethylenedithiolato complex containing an anionic carbon sigma donor. This compound shows an unprecedented fluxional behavior in solution, by which the three palladacycles exchange around the dithiolene.

Structure, stability and guest affinity of tris(3-ureidobenzyl)amine capsules in solution.

In non-competitive solvents, the tris(3-ureidobenzyl)amines 1 a-c form dimeric assemblies in which guests such as CH(3)CN, CH(3)NO(2), CH(2)Cl(2), CH(3)I, CH(2)BrCl, CH(2)Br(2), CHCl(3) and C(6)H(6) can be encapsulated. Variable temperature (1)H and (1)H,(1)H-ROESY NMR spectroscopy, as well as pulsed-gradient spin-echo (PGSE) diffusion measurements were used to investigate the encapsulation within 1 a1 a (1 a: tris{3-[N'-(4-butylphenyl)ureido]benzyl}amine). Kinetic parameters for the encapsulation of CH(3)NO(2), CH(2)Cl(2) and CH(3)I, both in CDCl(3) and in [D(8)]toluene have been obtained by using magnetisation transfer methods.

Ionic core-shell dendrimers with an octacationic core as noncovalent supports for homogeneous catalysts.

Ionic core-shell dendrimers with an octacationic core have been applied as noncovalent supports for homogeneous catalysts. Catalytically active arylpalladium complexes, which bear a tethered sulfato group, were noncovalently attached to the ionic core-shell dendritic supports via a straightforward ion-exchange reaction under mild conditions. Diagnostic shifts in (1)H NMR and Overhauser contacts show that the sulfato groups of the catalysts are located close to the octacationic core of the dendritic support in the resulting assemblies.

Pulsed gradient spin echo (PGSE) diffusion measurements as a tool for the elucidation of a new type of hydrogen-bonded bicapsular aggregate.

Compounds formed by linking two tris(ureidobenzyl)amine modules with a hexamethylene tether are described. These compounds self-assemble to form bicapsular aggregates featuring two rings of six hydrogen-bonded ureas. (1)H and (1)H/(1)H ROESY NMR spectroscopy, together with pulsed gradient spin echo (PGSE) NMR diffusion measurements, have been used to characterize the dimers in solution.

Multinuclear PGSE diffusion and overhauser NMR studies on a variety of salts in THF solution.

(1)H, (19)F, and (7)Li pulsed gradient spin-echo (PGSE) NMR measurements for a series of salts are reported. The (7)Li is shown to complement the (1)H and (19)F measurements; however, the use of higher concentrations (for the less-sensitive (7)Li) can lead to aggregation. For all of the salts discussed {Li(BF(4)); (n-Bu(4)N)(BF(4)), a trinuclear Ru cluster; [Ir(1,5-COD)(4)](BF(4)), where 4 is a chiral P,N ligand; and the crown ether stabilized potassium salt, [K(18-crown-6)(NPh(2))], 6}, the use of THF seems to promote strong ion pairing.

7Li, 31P, and 1H pulsed gradient spin-echo (PGSE) diffusion NMR spectroscopy and ion pairing: on the temperature dependence of the ion pairing in Li(CPh3), fluorenyllithium, and Li[N(SiMe3)2] amongst other salts.

7Li, 31P, and 1H variable-temperature pulsed gradient spin-echo (PGSE) diffusion methods have been used to study ion pairing and aggregation states for a range of lithium salts such as lithium halides, lithium carbanions, and a lithium amide in THF solutions. For trityllithium (2) and fluorenyllithium (9), it is shown that ion pairing is favored at 299 K but the ions are well separated at 155 K. For 2-lithio-1,3-dithiane (13) and lithium hexamethyldisilazane (LiHMDS 16), low-temperature data show that the ions remain together.

7Li PGSE diffusion measurements on LiPPh2: a solvent dependence of the structure.

The first application of 7Li pulsed-gradient spin-echo (PGSE) diffusion methods to structural lithium chemistry is reported. The data, which provide quantitative diffusion constants at 155 K, lead to a new method of estimating solvent viscosity at this temperature and clearly show a solvent dependence for the structure of LiPPh2. In THF, LiPPh2 exists as a mononuclear solvated species, whereas in Et2O, a dinuclear structure is found.

1H and 19F PGSE diffusion studies on iridium PHOX complexes: counterion and solvent dependences.

1H and (19)F pulsed gradient spin-echo (PGSE) diffusion studies on cationic mono- and trinuclear iridium complexes containing the PHOX chiral P,N-auxiliary (S)-4-tert-butyl-2-[2-(di-o-tolylphosphino)phenyl]-4,5-dihydrooxazole with the anions BF(4)(-), PF(6)(-), OTf(-), B(C(6)F(5))(4)(-), and BArF(-) in methanol, chloroform, methylene chloride, and 1,2-dichloroethane are reported. In chloroform, the anion and cation within each salt afford almost the same, relatively small, diffusion constant (D-value) suggesting strong ion-pairing. In methanol, the D-value for the cation is the same in the five mononuclear salts, suggesting that the cation is moving independently of the anion (no ion-pairing).

Synthesis and reactivity of a ferrocene-derived PCP-pincer ligand.

The 1,3-bis(diphosphinomethyl)ferrocene 3 readily reacts with [(C2H4)2RhCl]2 to form an equilibrating pair of diastereomers 8a and 8b by C-H insertion into the ferrocene.