Synthesis, x-ray analysis, and chemical properties of binuclear complexes with trans bis(palladium(II)-carbon) .sigma. bonds and bridging ligands (original) (raw)
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Solid State Sciences, 2010
The binuclear transition metal dialkynyl bridged Pd(II) complexes trans,trans-[ClPd(PBu 3 ) 2 eC^Ce C 6 H 4 eC 6 H 4 eC^CePd(PBu 3 ) 2 Cl] and trans,trans-[CH 3 OCeSePd(PBu 3 ) 2 eC^CeC 6 H 4 eC 6 H 4 eC^CePd (PBu 3 ) 2 eSeCOCH 3 ] were synthesized and investigated by X-ray Photoemission (XPS) and X-ray Absorption (XAS) spectroscopies. XPS measurements lead to assess that the thiolate terminal group does not affect dramatically the electronic structure of the transition metal, and as a consequence the two complexes are expected to possess analogous molecular structure. XAS data analysis suggested a squareplanar geometry around the palladium center in both binuclear compounds.
Inorganic Chemistry, 1979
X-ray photoelectron spectroscopic (XPS) data have been obtained for the binuclear Pd(I) complexes Pd2(dpm)2C12 and Pd2(dam),C12 (dpm = bis(dipheny1phosphino)methane and d a m = bis(dipheny1arsino)methane) and products resulting from the insertion of carbon monoxide, methyl isocyanide, sulfur dioxide, and atomic sulfur into the metal-metal bond. The insertion of these small molecules into the Pd-Pd bond results in either no change or modest increases in the Pd 3d5/2 binding energies (AEB of 0.0 to +0.6 eV) while the C1 2p3 2, P 2p3/2, or A s 3d binding energies of the attendant ligands remain constant. The largest Pd 3dSjz binding energy shifis arise from insertion of SOz. When observable, the binding energies of atoms in the inserted ligands decrease, sometimes substantially (0.9-2.5 eV), compared with those of their precursors. T h e small binding energy shifts of the Pd 3d levels are reasonable because only half of the charge donated to the inserted ligand comes from each half of the dipalladium complex. Similarly the binding energy shifts of the atoms of the inserted ligands (compared to those of their free, neutral precursors) become smaller, where detectable, as the number of atoms which compose the ligand increases. Nitrogen 1s binding energies for bridging methyl isocyanide in Pd2(dpm)2 (p-CNCH3)C12 and [Pd2(dpm)2(p-CIiCH3)(CNCH3)z] (PF6)2 are-1 eV lower than those for terminal methyl isocyanide. For comparison, XPS data are also presented for [Pd2(CNCH3)6](PF6)2, [Pd(CNCH3)4] (PF6)2, Pd(CNCH3)J2, and [Ptl(CNCH3)6](BF&, which contain only terminal, linearly bound CNCH3 ligands.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2018
Binuclear palladium(II) complexes with metal-metal (d 8-d 8) bonding interaction were synthesized by reactions of the 1-methyl-1H-1,2,3,4-tetrazole-5-thiol (Hmtzt) or a mixture of Hmtzt and 1,3propanediamine (1,3-pda) ligands. Complex [Pd 2 (μ-mtzt) 4 ].2CH 3 CN (1) was synthesized by the reaction of Pd(OAC) 2 with Hmtzt dissolved in acetonitrile and complex [Pd 2 (μ-mtzt) 2 (mtzt) 2 (1,3-pda)](2) was synthesized by reaction of a mixture of Hmtzt and 1,3-propanediamine (dissolved in methanol) with PdCl 2 (dissolved in acetonitrile) and were identified through elemental analysis, IR, UV-Vis, 1 H NMR, luminescence spectroscopy as well as single-crystal X-ray diffraction method. A single-crystal of complex 1 shows that two Pd(II) centers are linked together by four bridging tetrazole ligands providing a paddle wheel-like arrangement. Also a crystal structure of complex 2 shows that this complex possesses a symmetric structure in which one Pd atom is tetra-coordinated by four sulfur atoms to forms PdS 4 and other Pd atom is tetra-coordinated by four nitrogen to forms PdN 4 coordination sphere. Density functional theory (DFT) was performed in this study for the Hmtzt ligand and binuclear palladium(II) complexes (1) and (2). The DFT calculation shows Pd II-Pd II bond lengths of 2.831 and 3.086 Å in complex 1 and 2, respectively which are close to the observed bond lengths of 2.802(11) and 3.0911(17) Å from singlecrystal X-ray structure. The optimized geometry of the complexes is shown good agreement by X-ray data. Structural properties and molecular descriptors including bond lengths, bond angles, chemical hardness, dipole moment, HOMO-LUMO energy levels, electron transfer were analyzed The IR spectroscopy was performed using VEDA4 software and UV-Vis spectra were analyzed using timedependent density functional theory (TD-DFT) method. The theoretical and experimental data were also compared with each other.
Journal of the Brazilian Chemical Society, 2004
As reações de uma mistura [Pd 2 (dba) 3 ]/P(o-tolyl) 3 (1/4) com brometos de arila orto substituídos conduziram aos dímeros [Pd(Ar)(µ-Br){P(o-tolyl) 3)}] 2 que, após adição de 2 equiv. de (S)-BINAP formaram os complexos [PdBr(o-RC 6 H 4){(S)-BINAP}] em bons rendimentos (57-89%). A estrutura molecular do complexo [PdBr(o-C 6 H 4 CH 2 CON(H)Bn){(S)-BINAP}] (1) mostra o anel aromático aproximadamente perpendicular ao plano de coordenação com geometria quadrática plana ao redor do átomo de paládio. Como estes complexos apresentam rotação restrita da ligação paládio-aril e um ligante quiral, dois diastereoisômeros foram observados por 31 P{ 1 H} NMR. O comportamento dinâmico do complexo 1 em solução de CDCl 3 foi estudado por RMN de 31 P{ 1 H} (1, 13 CO-1 e 15 N-1) a varias temperaturas. O complexo enriquecido com 13 CO foi estudado também por RMN de 13 C{ 1 H}. Três espécies foram detectadas por RMN de 31 P{ 1 H} e 13 C{ 1 H} a baixas temperaturas (< 0 o C) e foram atribuídas como sendo os dois diastereoisomeros de 1 e o complexo catiônico [Pd(o-C 6 H 4 CH 2 CON(H)Bn) {(S)-BINAP}] + Br-. Acima de 40 o C observou-se somente os dois diastereoisômeros e a coalescência dos sinais pode ser observada por RMN de 13 C{ 1 H} a 80 o C. Não foi observada, na escala de tempo de RMN, nenhuma interconversão do complexo 1 em told 8 entre-35 at 120 o C. Entretanto, a interconversão entre os dois diastereoisômeros foi evidenciada por experimento de transferência de inversão no RMN de 31 P{ 1 H}. Os ciclopaladatos [Pd(o-C 6 H 4 CH 2 CONBn)L 2 ] [11 L 2 = DPPF, 68%; 12 L 2 = (S)-BINAP, 88 %] foram obtidos a partir das reações entre os complexos com NaO-t-Pn. A análise de RMN de 31 P{ 1 H} dos complexos 11 e 12 marcados com 15 N mostrou a presença da ligação Pd-N. A decomposição térmica do paladaciclo 12 conduziu ao heterociclo esperado e a uma amida como produto de redução. The complexes resulting from the 1:4 mixture of [Pd 2 (dba) 3 ] and P(o-tolyl) 3 in benzene react with ortho substituted-arylbromides to generate in situ the corresponding bromide dimer [Pd(Ar)(µ-Br){P(o-tolyl) 3)}] 2. Addition of 2 equiv. of (S)-BINAP gave the corresponding [PdBr(o-RC 6 H 4){(S)-BINAP}] in good yields (57-89%). The crystal structure of [PdBr(o-C 6 H 4 CH 2 CON(H)Bn){(S)-BINAP}] (1) shows a square planar arrangement around palladium with the aryl ring positioned nearly perpendicular to the square-planar coordination plane. Since these complexes exhibit restricted rotation about the palladium-aryl bond and contain a chiral ligand, they exist as two distinct diastereoisomers discernable by 31 P{ 1 H} NMR. The dynamic behavior of the complexes 1, 13 CO-1, and 15 N-1 in CDCl 3 was studied by 31 P{ 1 H} NMR spectroscopy. 13 CO-labeled 1 was also studied by 13 C{ 1 H} NMR. At temperatures below 0 o C three species were detected on the 31 P{ 1 H} and 13 C{ 1 H} NMR time scale. They were assigned as the two diastereoisomers and the cationic complex [Pd(o-C 6 H 4 CH 2 CON(H)Bn) {(S)-BINAP}] + Br. Above 40 o C only the two diastereoisomers were detectable. At higher temperatures rotation increased and at 80 o C a coalescence of the signals was observed by 13 C{ 1 H} NMR. However, no interconversion was observed for 1 in told 8 in the-35-120 o C range on the NMR time scale. In addition, the existence of the interconversion between the two isomers was directly demonstrated by an inversion transfer 31 P NMR experiment. The cyclopalladated complexes [Pd(o-C 6 H 4 CH 2 CONBn)L 2 ] [11 L 2 = DPPF, 68% yield; 12 L 2 = (S)-BINAP, 88 yield] were obtained by treatment of the aryl bromide complexes with NaO-t-Pn. 31 P{ 1 H} NMR spectra of the 15 N labeled complexes 11 and 12 clearly showed a Pd-N bond. Decomposition of the palladacycle 12 afforded the heterocycle and the amide reduced product.
Organometallic Complexes of Palladium(II) Derived from 2,6-Diacetylpyridine Dimethylketal
Organometallics, 2010
PdCl 2 reacts with 2,6-diacetylpyridine (dap) (1:1) in refluxing MeOH to give the pincer complex [Pd(O 1 ,N 1 ,C 1 -L)Cl] (1) and (QH) 2 [{PdCl 2 ( μ-Cl)}] 2 (2), where L is the monoanionic ligand resulting from deprotonation of the acetyl methyl group of the monoketal of dap and QH is C 5 H 3 NH{C-(OMe) 2 Me} 2 -2,6, the diketal of Hdap þ . Reaction of 2 with NEt 3 (1:2) in MeOH affords Q = C 5 H 3 N{C(OMe) 2 Me} 2 -2,6 (3). Complex 1 reacts with 2 equiv of RNC at 0°C to give trans-[Pd(C 1 -L)Cl(CNR) 2 ] (R = Xy = 2,6-dimethylphenyl (4a), t Bu (4b)) but at room temperature affords [Pd(O 2 , C 2 -L R )Cl(CNR)] (R = Xy (5a), t Bu (5b)). The ligand L R results from the insertion of one isocyanide into the Pd-C bond plus a tautomerization process from β-ketoimine to β-ketoenamine and coordinates in 5 through the carbonyl oxygen atom (O 2 ) and the inserted isocyanide carbon atom (C 2 ). The reaction of 1 with 1 equiv of RNC at 0°C leads to a mixture of [Pd(N 1 ,C 1 -L)Cl(CNR)] (R = Xy (6a), t Bu (6b); 85-90%), 1, and 4, but at room temperature gives the pincer complex [Pd(O 1 ,N 1 ,C 2 -L R )Cl] (R = Xy (7a), t Bu (7b)), resulting from insertion/tautomerization processes similar to that leading to 5. Complex 7 reacts at 0°C (1) with 2 equiv of RNC to give trans-[Pd(C 2 -L R )Cl(CNXy) 2 ] (R = Xy (8a), t Bu (8b)) or (2) with 1 equiv of t BuNC to afford 5b. The reaction of 1 (1) with [Tl(acac)] gives [Pd(N 1 ,C 1 -L)(acac)] (9); (2) with chelating ligands N ∧ N affords [Pd(C 1 -L)Cl(N ∧ N)] (N ∧ N = 2,2 0bipyridine = bpy (10), 4,4 0 -di-tert-butyl-2,2 0 -bipyridine = dbbpy (11)); (3) with 1 equiv of PPh 3 gives, in the same way as with isocyanides, an equilibrium mixture of [Pd(N 1 ,C 1 -L)Cl(PPh 3 )] (12), 1, and trans-[Pd(C 1 -L)Cl(PPh 3 ) 2 ] (13), which is the only product when 2 equiv of PPh 3 is added to the reaction mixture; and with excess PPh 3 affords the monoketal of dap, C 5 H 3 N{C(O)Me-2}{C(OMe) 2 Me-6} (14), and [Pd(PPh 3 ) 4 ]. The crystal structures of complexes 1, 2, 5b, 6a, and 7a have been determined. *Corresponding authors. E-mail: jvs1@um.es (J.V.); aurelia@um.es (A.A.). Web: http://www.um.es/gqo/.
Inorganic Chemistry, 2007
The short-bite aminobis(phosphonite), PhN{P(−OC 10 H 6 (µ-S)C 10 H 6 O−)} 2 (2), containing a mesocyclic thioether backbone is synthesized by either treating PhN(PCl 2) 2 with 2 equiv of thiobis(2,2′-naphthol) or reacting chlorophosphite (−OC 10 H 6 (µ-S)C 10 H 6 O−)PCl (1) with aniline in the presence of a base. Treatment of 2 with an equimolar amount of Pd(COD)Cl 2 in the presence of H 2 O affords a P−N−P-bridged and P,S-metalated binuclear complex, [PhN(P(− OC 10 H 6 (µ-S)C 10 H 6 O−)-κP) 2 Pd 2 Cl 2 {P(−OC 10 H 6 (µ-S)C 10 H 6 O−)(O)-κP,κS} 2 ] (3), whereas the same reaction with 2 equiv of Pd(COD)Cl 2 in the presence of H 2 O and Et 3 N produces the mononuclear anionic complex [{(−OC 10 H 6-(µ-S)C 10 H 6 O−)P(O)-κP,κS}PdCl 2 ](Et 3 NH) (5). By contrast, reaction of 2 with 2 equiv of Pd(COD)Cl 2 and H 2 O in the absence of Et 3 N gives the hydrogen phosphonate coordinated complex [{(−OC 10 H 6 (µ-S)C 10 H 6 O−)P(OH)}-PdCl 2 ] (4) which converts to the anionic complex in solution or in the presence of a base. Compound 2 on treatment with Pt(COD)X 2 (X) Cl or I) afforded P-coordinated four-membered chelate complexes [PhN(P(−OC 10 H 6 (µ-S)-C 10 H 6 O−)-κP) 2 PtX 2 ] (6 X) Cl, 7 X) I). The crystal structures of compounds 2, 3, 5, and 7 are reported. Compound 3 is the first example of a crystallographically characterized binuclear palladium complex containing a bidentate bridging ligand and its hydrolyzed fragments forming metallacycles containing a palladium−phosphorus σ bond. All palladium complexes proved to be very good catalysts for the Suzuki−Miyaura and Mizoroki−Heck cross-coupling and amination reactions with excellent turnover numbers (TON up to 1.46 × 10 5 in the case of the Suzuki−Miyaura reaction).
Canadian Journal of Chemistry, 1996
The reaction of [Ir,(CO),(dppm),] (dppm = Ph,PCH,PPh,) with dimethyl acetylenedicarboxylate (DMAD) first yields [ I~~(c o)~(~,-~' :~~-D M A D) (~~~~)~] (2) in which the alkyne is bound parallel to the metal-metal axis and the diphosphines are bound in a trans arrangement at both metals. This metastable isomer slowly rearranges to the stable form, [ I~~(C O) , (~,-~~:~~-D M A D) (~~~~)~] (3), in which the alkyne is now bound perpendicular to the metals and the diphosphines are bent back in a cis arrangement at both metals. The analogous species can be prepared by substituting hexafluoro-2-butyne (HFB) for DMAD; however, for the HFB adduct the isomer having the parallel geometry is seen only as a transient species; only [ I~~(C O)~(~,-~~:~~-H F B) (~~~~)~] (5) was isolated. Compound 2 reacts readily with PMe, to yield [Ir,(CO)(PMe,)(p,-CO)(p,-Tl:TL-~MAD)(dppm)2], and with CH,OSO,CF, to yield [Ir2(CH,)(CO)2(p,-T':T'-DMAD)(dppm)2][S0,C~,], whereas 3 reacts with neither reagent. Both 2 and 3 react with HBF4.0Et2 to yield the respective alkyne-bridged hydrides, [Ir2H(CO)2(p,-Tl:$-DMAD)(dppm),:I[BF,] and [I~~H(CO),(~,-~~:~~-DMAD)(~~~~)~~[BF,], in which the gross structural features and the alkyne coordination mode of the precursor are retained in each case. The latter species rearranges readily at ambient temperature, via migratory insertion, to give the vinyl-bridged product, [ I~, (C O) , (~,-~' :~~-R C = C(H)R)(dppm),][BF,] (R = C0,Me); however, the former is inert under these conditions, yielding the above vinyl species together with other decomposition products only upon reflux in benzene for several hours. Protonation of the perpendicular hexafluoro-2-butyne adduct also yields the corresponding vinyl product, together with decomposition products. The structure of 3, as the methylene chloride disolvate, was established by X-ray analysis. Crystal data are as follows. 3.2CH2C1,: C60H54C1406P41r2, monoclinic, P2/c, a = 26.088(5) A, b = 9.896(4) A, c = 23.954(3) A, P = 109.27(1)", Z = 4, R(F) = 0.038, R,(F,) = 0.0997 (all data).