Roberto Mosteiro

Cyclopalladated compounds with a bidentate [C, N]/terdentate [C, N, S] benzylidenethiophene imine ligand. Crystal and molecular structures of [Pd{2,3-(MeO)2C6H2C(H)NCH2(C4H3S)}(μ-OAc)]2, [Pd{2,3-(MeO)2C6H2C(H)NCH2(C4H3S)}(Cl)·(PPh3)] and [{Pd[2,3-(MeO)2C6H2C(H)NCH2(C4H3S)](Cl)}2(μ-Ph2P(CH2)4PPh2)]

Abstract Reaction of the Schiff base ligand 2,3-(MeO)2C6H3C(H)NCH2(C4H3S) (1), with palladium(II) acetate in toluene gave the dinuclear cyclometallated complex [Pd{2,3-(MeO)2C6H2C(H)NCH2(C4H3S)}(μ-OAc)]2 (2), with the ligand bonded to the palladium atom through the imine nitrogen and the C6 carbon atom. The X-ray crystal structure of complex 2 is described. The reaction of 2 with aqueous sodium chloride gave the chloro-bridged complex [Pd{2,3-(MeO)2C6H2C(H)NCH2(C4H3S)}(μ-Cl)]2 (3), after a metathesis reaction. Reaction of 3 with PPh3 in acetone gave the mononuclear cyclometallated complex [Pd{2,3-(MeO)2C6H2C(H)NCH2(C4H3S)}(Cl)(PPh3)] (4), in a bridge-splitting reaction. Treatment of 4 with silver triflate gave the cyclometallated complex [Pd{2,3-(MeO)2C6H2C(H)NCH2(C4H3S)}(PPh3)][CF3SO3] (7), with the palladium atom bonded to four different atoms C, N, S and P. Reaction of 3 with the diphosphines dppp and dppb in a 1:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[2,3-(MeO)2C6H2C(H)NCH2(C4H3S)](Cl)}2(μ-Ph2P(CH2)nPPh2)] (5: n=3; 6: n=4), with the diphosphine bridging the two palladium atoms. The X-ray crystal structures of complexes 4 and 6 are reported.

Sterically controlled reactivity of palladium(ii) tetranuclear cyclometallated complexes. Crystal and molecular structure of the novel tetranuclear compound [Pd2{1,3-[C(H)NCH2C4H7O]2C6H2}(µ-Cl)(Cl)(PPh3)]2Electronic supplementary information (ESI) available: 1H and 31P NMR data for compounds 1–15 and 17. See http://www.rsc.org/suppdata/nj/b1/b111671a/

The reaction of the Schiff base ligands 1,3-[CN(H)CH2C4H7O]2C6H4 (1) and 1,4-[CN(H)CH2C4H7O]2C6H4 (14) with palladium(II) acetate in toluene gave the acetato-bridged cyclometallated compounds [Pd2{1,3-[C(H)NCH2C4H7O]2C6H2}(μ-AcO)2]2 (2) and [(μ-AcO)Pd{1,4-[C(H)NCH2C4H7O]2C6H2}Pd(μ-AcO)]n (15). Reaction of 2 and 15 with aqueous sodium chloride gave the chloro-bridged cyclometallated compounds [Pd2{1,3-[C(H)NCH2C4H7O]2C6H2}(μ-Cl)2]2 (3) and [(μ-Cl)Pd{1,4-[C(H)NCH2C4H7O]2C6H2}Pd(μ-Cl)]n (16), respectively, after a metathesis reaction. Reaction of 3 with triphenylphosphine in a 1∶2 molar ratio gave the tetranuclear complex [Pd2{1,3-[C(H)NCH2C4H7O]2C6H2}(μ-Cl)(Cl)(PPh3)]2 (4), where only one of the bridging PdCl2Pd moieties was cleaved, and which was characterized by X-ray crystal structure analysis. However, reaction of 16 with PPh3 gave the dinuclear complex [(PPh3)(Cl)Pd{1,4-[C(H)NCH2C4H7O]2C6H2}Pd(PPh3)(Cl)] (17) after a full bridge-splitting reaction. Similarly, treatment of 3 with PMe2Ph, pyridine and thallium acetylacetonate produced the dinuclear complexes 5, 6 and 7, respectively. Treatment of 4 with pyridine in a 1∶2 molar ratio, and with 4,4′-dipyridyl in an 1∶1 molar ratio, gave the di- and tetranuclear complexes 12 and 13, respectively. Reaction of 3 with the tertiary diphosphine cis-Ph2PCHCHPPh2 in a 1∶2 molar ratio yielded the tetranuclear complex [Pd2{1,3-[C(H)NCH2C4H7O]2C6H2}(μ-Cl)(Ph2PCHCHPPh2-P,P)][Cl]2 (8) after selective splitting of one of the PdCl2Pd bridging moieties. However, reaction of 3 with cis-Ph2PCHCHPPh2 and Ph2P(CH2)2PPh2 in 1∶4 molar ratios gave the dinuclear complexes 9 and 10, respectively. Reaction of 3 with the diphosphine Ph2PC5H4FeC5H4PPh2 in a 1∶2 molar ratio yielded the trinuclear complex [Pd2{1,3-[C(H)NCH2C4H7O]2C6H2}(μ-Ph2PC5H4FeC5H4PPh2)] (11), with the diphosphine bridging the two palladium atoms of the dicyclometallated moiety.

Cyclometallated complexes of Pd(II) with heterobidentate P, As and P, N coordinating ligands

Treatment of the choride-bridged dimer [Pd{4-(COH)C6H3C(H)/N(Cy)/C2 ,N }(m-Cl)]2 (1), with Ph2PCH2CH2AsPh2 (arphos) in 1:1 molar ratio in acetone gave the dinuclear complex [{Pd[4-(COH)C6H3C(H)/N(Cy)/C2 ,N ](Cl)}2(m-Ph2PCH2CH2AsPh2)] (2), with the arsinophosphine as a bridging ligand, and in 1:2 molar ratio in the presence of NH4PF6 gave the mononuclear compound [Pd{4-(COH)C6H3C(H)/N(Cy)/C2 ,N }(Ph2PCH2CH2AsPh2/P ,As )][PF6], (3), with the arsinophosphine chelated to the metal center. Reaction of 1 with Ph2PCH2CH2CH2NH2 in 1:2 molar ratio in acetone and NH4PF6 afforded [Pd{4-(COH)C6H3C(H)/ N(Cy)/C2 ,N }{Ph2PCH2CH2CH2N(/CMe2)/P ,N }][PF6 ]( 4), after intermolecular condensation between the aminophosphine and the solvent. Condensation was precluded by treatment in toluene to give the mononuclear compound [Pd{4-(COH)C6H3C(H)/ N(Cy)/C2 ,N }(Ph2PCH2CH2CH2NH2/P ,N )][PF6], (5). 1 H, 31 P{ 1 H} and 13 C{ 1 H}-NMR, IR and mass spectral data are given. The crystal structures of compounds 2 � /4 have been determined by X-Ray crystallography. # 2002 Elsevier Science B.V. All rights reserved.

Directed regioselectivity in cyclometallated palladium(II) compounds of N-benzylidenebenzylamines. Crystal and molecular structure of [Pd{3,4-(OCH2O)C6H2C(H)NCH2[3,4-(OCH2O)C6H3]-C2,N}(μ-O2CMe)]2

Abstract The reaction of the Schiff base ligand 3,4-(OCH2O)C6H3C(H)NCH2[3,4-(OCH2O)C6H3] (a) with Pd(OAc)2 yields two endocyclic cyclometallated compounds: [Pd{3,4-(OCH2O)C6H2C(H)NCH2[3,4-(OCH2O)C6H3]-C2,N}(μ-O2CMe)]2 (C2,N-bonded) (1a), and [Pd{3,4-(OCH2O)C6H2C(H)NCH2[3,4-(OCH2O)C6H3]-C6,N}(μ-O2CMe)]2 (C6,N-bonded) (1b), which may be separated by fractional crystallization. The corresponding cyclopalladated dimers with bridging chloride ligands, 2a, 2b, have been prepared by a metathesis reaction with aqueous sodium chloride. Treatment of the latter compounds with tertiary phosphines in the appropriate molar ratio gave the mono and dinuclear compounds, 3a–8a and 3b–5b, respectively. The structure of compound 1a has been determined by X-ray diffraction analysis. The molecular configuration is a dimeric form of the anti isomer with the cyclopalladated moieties in an ‘open-book’ arrangement linked by two acetate bridging ligands.

Cyclopalladated compounds derived from (C,N,O) terdentate ligands: synthesis, characterization and reactivity

Treatment of the Schiff base ligands 2-ClC6H4C(H)NCH2(C4H7O) (a) and 3,4-(MeO)2C6H3C(H)NCH2(C4H7O) (b) with palladium(II) acetate in toluene or glacial acetic acid gave the dinuclear cyclometallated complexes [Pd{2-ClC6H3C(H)NCH2(C4H7O)}(-OAc)]2 (1a) and [Pd{3,4-(MeO)2C6H2C(H)NCH2(C4H7O)}(-OAc)]2 (1b) with the ligand bonded to the palladium atom through the imine nitrogen and the C6 carbon atom. The 1 Ha nd 13 C–{ 1 H} NMR spectra of the complexes show the occurrence in solution of three pairs of enantiomers. The acetato-bridged cyclometallated complex [Pd{3,4(MeO)2C6H2C(H)NCH2(C4H7O)}(-OAc)]2 (1c) was prepared from the enantiopure ligand (R)-3,4-(MeO)2C6H3(H) NCH2(C4H7O) (c). The NMR spectra of 1c showed the existence of only two diastereomers in the solution. The reaction of 1a and 1b with aqueous sodium chloride gave the chloro-bridged complexes [Pd{2-ClC6H3C(H)NCH2(C4H7O)}(-Cl)]2 (2a )a nd [Pd{3,4-(MeO)2C6H2C(H)NCH2(C4H7O)}(-Cl)]2 (2b) after a metathesis reaction. The reaction of 2a with PPh3 in acetone gave the mononuclear cyclometallated complex [Pd{2-ClC6H3C(H)NCH2(C4H7O)}(Cl)(PPh3)] (3a) in a bridge-splitting reaction. Treatment of 3a with silver triflate gave the cyclometallated complex [Pd{2-ClC6H3C(H)NCH2(C4H7O)}(PPh3)][CF3SO3 ]( 4a )i n which the palladium atom is bonded to four different atoms C, N, O and P. When complex 2a was reacted with silver triflate in acetone complex [Pd{2-ClC6H3C(H)NCH2(C4H7O)}((CH3)2CO)][CF3SO3 ]( 5a) was obtained with the ligand as [C,N,O] coordinated. The reaction of complexes 2a and 2b with the diphosphine dppp in a complex–phosphine 1:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[2-ClC6H3C(H)NCH2(C4H7O)](Cl)}2(-Ph2P(CH2)3PPh2)] (8a) and [{Pd[3,4-(MeO)2C6H2C(H)NCH2(C4H7O)](Cl)}2(-Ph2P(CH2)3PPh2)] (5b) with the diphosphine bridging the two palladium atoms. Reaction of complexes 2a and 2b with the phosphines dppp and cis-dppe in a 1:2 molar ratio gave the mononuclear complexes [Pd{2ClC6H3C(H)NCH2(C4H7O)}{Ph2P(CH2)3Ph2-P,P}][ClO4 ]( 6a), [Pd{3,4-(MeO)2C6H2C(H)NCH2(C4H7O)}{Ph2P(CH2)3Ph2 – P,P}][ClO4 ]( 3b) and [Pd{2-ClC6H2C(H)NCH2(C4H7O)}(cis-Ph2PCHCHPh2 –P,P)][Cl] (4b). The treatment of 2a with the triphosphine bis(2-diphenylphosphinoethyl)phenylphosphine in 1:2 molar ratio, followed by treatment with sodium perchlorate gave [Pd{3,4-(MeO)2ClC6H3C(H)NCH2(C4H7O)}{(PPh2CH2CH2)2PPh-P,P,P}][ClO4 ]( 7a) in which the palladium atom is bonded to the triphosphine through the three phosphorus atoms and to the Schiff base ligand through one carbon atom and the imine nitrogen.

Nucleophilic addition of 1,3-dicarbonyl compounds as a route to functionalized cyclopalladated complexes with chelated 1,1-bis(diphenylphosphino)ethene

Treatment of the chloride-bridged complex [Pd{2,4-(OMe)2C6H2C(H)N(Cy)-C6,N}(μ-Cl)]2 (1) with 1,1-bis(diphenylphosphino)ethene (vdpp) and NH4PF6 or NaClO4 in 1∶2 molar ratio afforded the mononuclear cyclometallated palladium(II) complexes [Pd{2,4-(OMe2)C6H2C(H)N(Cy)-C6,N}{(Ph2P)2CCH2-P,P′}](X) (2, X = PF6; 3, X = ClO4). The structure of 2 has been determined by X-ray diffraction analysis. Reaction of 2 with acetylacetone in the presence of anhydrous sodium carbonate yielded in high yield the addition product [Pd{2,4-(MeO)2C6H2C(H)N(Cy)-C6,N}{(Ph2P)2CHCH2CH(COMe)2-P,P′}](PF6) (4). The 31P-{1H} NMR spectrum showed a greater 2J(PP) coupling constant than the one observed for the starting complex. Reaction of 2 with diethyl malonate afforded a 7∶3 mixture of the addition product [Pd{2,4-(MeO)2C6H2C(H)N(Cy)-C6,N}{(Ph2P)2CHCH2CH(COOEt)2-P,P′}](PF6) (5) and the starting complex. The desired addition compound could be isolated in pure form by treatment of 3 with diethyl malonate yielding [Pd{2,4-(MeO)2C6H2C(H)N(Cy)-C6,N}{(Ph2P)2CHCH2CH(COOEt)2-P,P′}](ClO4) (16). The reaction of 2 with asymmetric nucleophiles such as methyl acetoacetate, ethyl propionylacetate, ethyl acetoacetate, methyl 4-chloroacetoacetate, 1,1,1-trifluoroacetylacetone and thenoyltrifluoroacetone afforded the corresponding addition derivatives, [Pd{2,4-(MeO)2C6H2C(H)N(Cy)-C6,N}{(PH2P)2CHCH2CH(COR1)(COR2)-P,P′}](PF6) (R1 = Me, R2 = OMe, 6; R1 = Et, R2 = OEt, 7; R1 = Me, R2 = OEt, 8; R1 = CH2Cl, R2 = OMe, 9; R1 = Me, R2 = CF3, 10; R1 = CF3, R2 = 2-SC4H3, 11). The NMR spectra showed some resonances were duplicated, suggesting the existence of optical isomers, as a consequence of the existence of two chiral carbon atoms in the diphosphine moiety, (Ph2P)2C*HCH2C*H(COR1)(COR2). The molecular structure of compound 7 has been determined by X-ray crystallography confirming the spectroscopic data. The crystal structure of 7 comprises equimolar amounts of the (C16R, C18S) and (C16S, C18R) enantiomers. Reaction of 2 with 1-(2-furyl)-1,3-butanedione, ethyl 2-methylacetoacetate, 3-chloroacetylacetone and methyl 2-chloroacetoacetate gave compounds [Pd{2,4-(MeO)2C6H2C(H)N(Cy)-C6,N}{(Ph2P)2CHCH2C(R1)(COMe)(COR2)-P,P′}](PF6) (R1 = H, R2 = 2-OC4H3, 12; R1 = Me, R2 = OEt, 13; R1 = Cl, R2 = Me, 14; R1 = Cl, R2 = OMe, 15). The 2J(PP) coupling constants for 14 and 15 were smaller than in the other addition compounds due to the presence of the neighbouring chlorine atom. Treatment of 2 with 3-ethylacetylacetone or 2,2,6,6-tetramethyl-3,5-heptanedione did not give any addition product. However, reaction of 3 with 3-ethylacetylacetone yielded a mixture of 3/[Pd{2,4-(MeO)2C6H2C(H)N(Cy)-C6,N}{(Ph2P)2CHCH2C(Et)(COMe)2-P,P′}](ClO4) (17) in 1∶1 molar ratio.