Synthesis of Bis(2,6-dinitroaryl)palladium(II) and Mono(2,6-dinitroaryl)platinum(II) Complexes. A New Example of the Transphobia Effect and of Transmetalation from Pt to Hg

Reactions of Cycloplatinated Guanidine Complexes with Hg(OC(O)CF3)2: Formation of a One-Dimensional Coordination Polymer Containing a Pt2Hg(μ2-S(O)Me2-S,O) Repeating Unit versus a Discrete Pt2Hg2 Complex

Separate reactions of cycloplatinated 2-tolyl- and 2-anisylguanidine complexes, [Pt{κ²(C,N)}(OC(O)CF₃)(S(O)Me₂)] (1 and 2), with Hg(OC(O)CF₃)₂ in 1:0.5 and 1:1 molar ratios afforded the one-dimensional coordination polymer (1D CP) {[Pt^III{κ²(C,N)}(OC(O)CF₃)₂]₂Hg⁰}(μ₂-S(O)Me₂-S,O)·C₇H₈ (3·C₇H₈) as bright red crystals and the discrete tetrametallic complex [Pt^II{κ²(C,N)}(μ₂-OC(O)CF₃)₂Hg^I-]₂ (4) as yellow crystals in good yields. The two different products obtained in the aforementioned reactions are ascribed to the subtle differences in the N substituent of the guanidinate(1-) ligands in 1 and 2. The plausible mechanisms of formation of 3 and 4 are outlined. Complexes 3 and 4 were characterized by elemental analyses and IR and multinuclear NMR (¹H, ¹³C{¹H}, ¹⁹F, and ¹⁹⁵Pt) spectroscopy. Complex 4 was also characterized by ¹⁹⁹Hg NMR spectroscopy. The molecular structures of 3·C₇H₈ and 4 were determined by single-crystal X-ray diffraction studies. 1D CP 3·C₇H₈ contains a Pt(III)-Hg(0)-Pt(III)(μ₂-S(O)Me₂-S,O) repeating unit with a pair of unsupported Pt-Hg covalent bonds, while 4 contains a Pt(II)-Hg(I)-Hg(I)-Pt(II) chain with a pair of trifluoroacetate ligand supported Pt→Hg coordinate bonds. 1D CP 3·C₇H₈ falls apart into a mixture of three species, namely 6-8 and 9-11 in C₆D₆ and CDCl₃, respectively, as revealed by multinuclear NMR spectroscopy. In CDCl₃, 4 partially isomerizes to [Pt^II(OC(O)CF₃)(μ₂-OC(O)CF₃){κ³μ₂(C,N,O)}Hg^I-]₂ (12), wherein each Pt→Hg coordinate bond is supported by one μ₂-bridging trifluoroacetate ligand and one chelating bridging guanidinate(1-) ligand, as inferred from variable-temperature ¹H and ¹⁹F NMR spectroscopy. Complex 12 is the major species and 4 is the minor species in CDCl₃, while opposite situation prevails in C₆D₆. The observance of a mixture of two solution species for 4 is ascribed to a rapid "carboxylate shift" process induced by the oxygen atom of the ═N(C₆H₄(OMe)-2) unit of the guanidinate(1-) ligand through neighboring-group participation. UV-visible absorption and emission spectra of 4 were measured in CHCl₃, and from the outcome of the investigation, the possible existence of [Cl₂(H)C-Cl···Pt^II(OC(O)CF₃)(μ₂-OC(O)CF₃){κ³μ₂(C,N,O)}Hg^I-]₂ (12″) was suggested, which is likely to have a pair of Pt-Hg covalent bonds made possible by CHCl₃ coordination on the sixth site of the Pt(II) atom.

Syntheses and structural aspects of six-membered palladacyclic complexes derived fromN,N′,N′′-triarylguanidines with N- or S-thiocyanate ligands

Linkage isomers8·2/3PhMe and9·MeOH were synthesized, isolated and structurally characterized by SCXRD and the role of solvent of crystallization in the formation of these linkage isomers identified.

trans–cis C–Pd–C rearrangement in hemichelates

In the transition state of the trans–cis isomerization process, hemichelation dynamically offers alternative coordination positions to the Pd center.

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. Insertion of CO takes place into the Pd-C bond of complexes 1a,b, affording Pd(0) and the tetrahydro-benzazepinone 5a or 5b, which possesses potential pharmacological interest. Additionally, the triflate salt A or B undergoes catalytic carbonylation with CO to afford the corresponding N,N'-dialkylurea, using Pd(OAc)2/Cu(OAc)2, in boiling acetonitrile. The crystal structures of 3a·(1)/2H2O, 3b, 4b·CHCl3, and 5a were determined by X-ray diffraction studies.

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)].

Regioselective functionalization of iminophosphoranes through Pd-mediated C-H bond activation: C-C and C-X bond formation

The orthopalladation of iminophosphoranes [R(3)P=N-C(10)H(7)-1] (R(3) = Ph(3) 1, p-Tol(3) 2, PhMe(2) 3, Ph(2)Me 4, N-C(10)H(7)-1 = 1-naphthyl) has been studied. It occurs regioselectively at the aryl ring bonded to the P atom in 1 and 2, giving endo-[Pd(μ-Cl)(C(6)H(4)-(PPh(2=N-1-C(10)H(7))-2)-κ-C,N](2) (5) or endo-[Pd(μ-Cl)(C(6)H(3)-(P(p-Tol)(2)=N-C(10)H(7)-1)-2-Me-5)-κ-C,N](2) (6), while in 3 the 1-naphthyl group is metallated instead, giving exo-[Pd(μ-Cl)(C(10)H(6)-(N=PPhMe(2))-8)-κ-C,N](2) (7). In the case of 4, orthopalladation at room temperature affords the kinetic exo isomer [Pd(μ-Cl)(C(10)H(6)-(N=PPh(2)Me)-8)-κ-C,N](2) (11exo), while a mixture of 11exo and the thermodynamic endo isomer [Pd(μ-Cl)(C(6)H(4)-(PPhMe=N-C(10)H(7)-1)-2)-κ-C,N](2) (11endo) is obtained in refluxing toluene. The heating in toluene of the acetate bridge dimer [Pd(μ-OAc)(C(10)H(6)-(N=PPh(2)Me)-8)-κ-C,N](2) (13exo) promotes the facile transformation of the exo isomer into the endo isomer [Pd(μ-OAc)(C(6)H(4)-(PPhMe=N-C(10)H(7)-1)-2)-κ-C,N](2) (13endo), confirming that the exo isomers are formed under kinetic control. Reactions of the orthometallated complexes have led to functionalized molecules. The stoichiometric reactions of the orthometallated complexes [Pd(μ-Cl)(C(10)H(6)-(N=PPhMe(2))-8)-κ-C,N](2) (7), [Pd(μ-Cl)(C(6)H(4)-(PPh(2)[=NPh)-2)](2) (17) and [Pd(μ-Cl)(C(6)H(3)-(C(O)N=PPh(3))-2-OMe-4)](2) (18) with I(2) or with CO results in the synthesis of the ortho-halogenated compounds [PhMe(2)P=N-C(10)H(6)-I-8] (19), [I-C(6)H(4)-(PPh(2)=NPh)-2] (21) and [Ph(3)P=NC(O)C(6)H(3)-I-2-OMe-5] (23) or the heterocycles [C(10)H(6)-(N=PPhMe(2))-1-(C(O))-8]Cl (20), [C(6)H(5)-(N=PPh(2)-C(6)H(4)-C(O)-2]ClO(4) (22) and [C(6)H(3)-(C(O)-1,2-N-PPh(3))-OMe-4]Cl (24).

Transmetalation supported by a Pt(II)-Cu(I) bond

Passing Me over: platinum-to-copper methyl transfer is observed upon collision-induced dissociation (CID) of the cations formed by the interaction of the [(R(3)P)Cu](+) fragment with [(dmpe)PtMe(2)] (R=Me, Ph, Cy, tBu; dmpe=bis(dimethylphosphino)ethane; see X-ray crystal structure of coordination spheres for R=tBu). The thermochemistry of these processes for R=Me is investigated by mass-spectrometric methods.

Unexpected [2 + 2] C-C bond coupling due to photocycloaddition on orthopalladated (Z)-2-aryl-4-arylidene-5(4H)-oxazolones

A [2 + 2] photocycloaddition has been observed in regioselectively orthopalladated 2-aryl-4-arylidene-5(4H)-oxazolones, leading to unprecedented cyclobutane-bis(oxazolones).