Jesús J. Fernández

Synthesis of cyclometallated complexes of PdII. The X-ray crystal structure of di-μ-bromo-bis[N-(3,4-dimethoxybenzylidene)cyclohexylaminato-C6,N]dipalladium(II)

Abstract The structure of the cyclometallated bromo-brided palladium(II) dimer complex [P d{3,4-(MeO) 2 C 6 H 2 C(H)&.dbnd;N Cy}(Br)] 2 is described. This is the first example of a structurally characterised cyclometallated bromo-bridged dimer. Crystals were triclinic, space group P 1 with a = 788.7(2), b = 911.0(3), c = 1480.(4) pm, α = 96.94(2), β = 91.57(2), γ = 101.85(2)°, Z = 1, U = 1.0322(5) nm 3 , R = 0.0688, R w = 0.790, for 3280 independent reflections with F >4.0σ( F ). The structure is a centrosymmetric palladium dimer with two asymmetrically bridging bromine atoms and non-bonding Pd⋯Pd distance of 363.1(5) pm. The synthesis of the iodo-bridged analogue and the reactions of these two dimers and the chloro-bridged analogue with various tertiary phosphines are also described.

Cyclometallated complexes of PdII and MnI with N,N-terephthalylidenebis(cyclohexylamine)

Treatment of N,N-terephthalylidenebis(cyclohexylamine), 1,4-(CyNCH)2C6H4 (Cy = cyclohexyl) with palladium(II) acetate in glacial acetic acid gave the monocyclometallated dimer complex [{Pd[4-(CHO)C6H3CHNCy](O2CMe)}2] (1) which was shown to have a free formyl group on each phenyl ring by IR and 1H and 13C-{1H} NMR spectroscopy. Treatment of 1,4-(CyNCH)2C6H4 with [MnMe(CO)5] in octane gave the doubly cyclometallated complex [(OC)4MnN(Cy)C(H)CC6H2C(H)N(Cy)Mn(CO)4] (2). Reaction of 1 with aqueous sodium chloride, bromide or iodide gave the monocyclometallated dimer complexes [{Pd[4-(CHO)C6H3C(H)NCy](X)}2] [X = Cl (3), Br (4), or I (5)]. Complexes 1, 3 and 4 react with amines to give the corresponding cyclometallated dimer complexes [Pd{4-(CyNCH)C6H3C(H)NCy}(O2CMe)]2 (6) and [{Pd[4-(CyN=CH)C6H3C(H)=NR](X)}2] [X = Cl (7), X = Br (8) R = Cy; X = Cl, R = 2,4,6-Me3C6H2 (9)] with an uncoordinated C=N group on each phenyl ring. Treatment of 3, 4 or 5 with thallium acetylacetonate gave the cyclometallated monomer compound [Pd{4-(CHO)C6H3C(H)=NCy}-(CH3COCHCOCH3)] (10) with a chelating 2,4-pentanedionate group. Treatment of 3, 4 or 5 with tertiary phosphines in a dimer/ phosphine 1:2 or 1:4 molar ratio afforded the cyclometallated [Pd{4-(CHO)C6H3C(H)=NCy}(X)(L)] (11–18) and noncyclometallated [Pd{4-(CHO)C6H3C(H)=NCy}(X)(L)2] (25–31) (X=Cl, Br, or I; L=PPh3, PPh2Et, PPhEt2, or PPh2Me). Reaction of 11–13 with cyclohexylamine (L=PPh3) gave the non-cyclometallated compounds [Pd{4-(CyN=CH)C6H3C-(H)=NCy}(X)(PPh3)(NH2Cy)] (19–21) with two uncoordinated C=N groups whereas reaction of 14–18 with cyclohexylamine (L = PPh2Et, PphEt2, or PPh2Me) gave the cyclometallated compounds [Pd{4-(CyN=CH)C6H3C(H)=NCy}(X)(L)] (22–24). Compounds 25 and 29 gave [Pd{4-(CyN=CH)C6H3C)(H)=NCy}(Cl)(L)2] (32,33) (L= PPh3, or PPh2Et) when treated with cyclohexylamine. IR and 1H, 13C and 31P NMR data are discussed.

Cyclometallated complexes of palladium(II) with a C, N, N′ terdentate Schiff base donor ligand. Oxidative addition of an arylchlorine bond to palladium(O)

Treatment of N-(2-chlorobenzylidene)-N,N′-dimethylethylenediamine, 2-ClC6H4C(H)NCH2CH2NMe2, with tris(dibenzylideneacetone)dipalladium(0) in chloroform gave the oxidative addition cyclometallated product [Pd{C6H4C(H)NCH2CH2NMe2}(Cl)] (1) with the palladium atom bonded to a C,N,N′ terdentate donor ligand. Treatment of 1 with tertiary monophosphines gave the cyclometallated complexes [Pd{C6H4C(H)NCH2CH2NMe2}(Cl)(L)](2: L  PPh3; 3: L  PEtPh2; 4: L  PEt2Ph; 5: L  PEt3), where the phosphine ligand is either trans to the phenyl carbon atom (2, 3) or trans to the imine nitrogen atom (4, 5). Treatment of 1 with silver perchlorate followed by reaction with tertiary monophosphines gave the cyclometallated complexes [Pd{C6H4C(H)NCH2CH2NMe2}(L)][ClO4] (6: L  PPh3; 7: L  PEtPh2; 8: L  PEt2Ph; 9: L  PEt3). Reaction of 1 with thallium acetylacetonate gave the cyclometallated complex [Pd{C6H4C(H)NCH2CH2NMe2}(H3CCOCHCOCH3)] (10). Treatment of 1 with ditertiary diphosphines in a complex 1/diphosphine 2:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[C6H4C(H)NCH2CH2NMe2](Cl)}2(LL)(11: LL = trans-Ph2PCHCHPPh2; 12: LL  Ph2P(CH2)3PPh2;13: LL  Ph2P(CH2)4PPh2), where the phosphorus atom is trans to the phenyl carbon atom. Treatment of 1 with silver perchlorate followed by ditertiary diphosphines in a complex 1/diphosphine 2:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[C6H4C(H)NCH2CH2NMe2]}2 (LL)][ClO4]2 [14: LL=trans-Ph2PCHCHPPh2; 15: LL  Ph2P(CH2)3PPh2; 16: LL  Ph2P(CH2)4PPh2)]. Reaction of 1 with ditertiary diphosphines in a complex 1/diphosphine 1:1 molar ratio, and silver perchlorate as appropriate, gave the cyclometallated complexes [Pd{C6H4C(H)NCH2CH2NMe2}(Ph2P(CH2)2PPh2-P,P)][ClO4] (17), [Pd{C6H4C(H)NCH2CH2NMe2}(Ph2P(CH2)3PPh2-P,P)][ClO4] (18), [Pd{C6H4C(H)NCH2CH2NMe2}(cis-Ph2PCHCHPPh2-P,P)][Cl] (19) and [Pd{C6H4C-(H)NCH2CH2NMe2}(Cl)(Ph2P(CH2)4PPh2-P,P)] (20).

New cyclometallated platinum(II) compounds with thiosemicarbazones: crystal and molecular structure of [Pt{4-MeC6H3C(Me)NNC(S)NH2}(PPh3)]

Abstract Treatment of the thiosemicarbazones 3-CH3(CH2)5OC6H4C(Me)NN(H)C(S)NH2 (a), 4-MeC6H4C(Me)NN(H)C(S)NH2 (b), C6H5C(Et)NN(H)C(S)NH2 (c), C6H5C{CH3(CH2)10}NN(H)C(S)NH2 (d) and 4-MeC6H4C(Me)NN(H)C(S)NHMe (e) with K2[PtCl4] gives tetranuclear platinum(II) compounds 1a–1e with deprotonation of the NH group and with the ligand acting as a terdentate [C,N,S] moiety. Reaction of 1a–1e with PPh3 and of 1a with P(4-MeOC6H4)3 yielded mononuclear species 2a–2e and 3a, respectively. Treatment of 1a with the diphosphines Ph2PCH2PPh2 (dppm), Ph2P(CH2)2PPh2 (dppe), Ph2P(CH2)3PPh2 (dppp), Ph2P(CH2)4PPh2 (dppb), Ph2P(CH2)5PPh2 (dpppe), Ph2P(CH2)6PPh2 (dpph), and 1,1′-ferrocenebis(diphenylphosphine) (dppf) gives dinuclear compounds 4a–10a. In all cases the PdSchelating bond is strong enough to withstand reaction with the phosphorus ligands without bond cleavage. The molecular structure of 2b has been determined by X-ray crystallography. Mononuclear units are held together by hydrogen bonding, forming dimers in the solid state.

Influence of phenyl ring substituents in the cyclometallation of Schiff base ligands: crystal and molecular structures of [Pd-{3,4-(OCH2O)C6H2C(H)N(Cy)-C2,N}(μ-O2CMe)]2 and [Pd-{3,4-(OCH2CH2O)C6H2C(H)N(Cy)-C6,N}(μ-O2CMe)]2

Abstract Reaction of Pd(OAc)2 with the Schiff base ligands 3,4-{O(CH2)nO}C6H3C(H)NR (n=1, 2; R=Cy, 3,4-(OCH2O)C6H3CH2-) leads to dinuclear cyclometallated products in which each palladium atom is C,N bonded to a deprotonated organic ligand, and to two acetate groups which bridge both metal centers. Treatment of 3,4-{O(CH2)2O}C6H3C(H)NCH2CH2NMe2 with [PtMe2(COD)] gives mononuclear compounds with the ligand as terdentate through the [C, N, N] atoms. The regioselectivity of the cyclometallation processes is discussed by 1H-NMR spectroscopy and X-ray diffraction studies.

Synthesis of complexes of platinum (II) with C,N,N′-terdentate Schiff base donor ligands. Crystal and molecular structure of [Pt{3-Me-4-MeOC6H2C(H)NCH2CH2NMe2}(Me)]

Abstract Treatment of the potentially terdentate ligands C6RxH5−xC(H)N–CH2CH2NMe2 [R: a (x=2), 2,4-(MeO)2; b (x=2), 3,4-(MeO)2; c (x=2), 3-Me-4-MeO; d (x=3), 2,3,4-(MeO)3; e (x=2), 4,5-(OCH2O); f (x=1), 2-NO2] with [PtMe2(COD)] gave the platinated compounds [Pt{C6RxH4−xC(H)NCH2CH2–NMe2}(Me)] with two fused five-membered rings at platinum. The crystal and molecular structure of [Pt{3-Me-4-MeOC6H2C(H)NCH2CH2NMe2}(Me)] has been determined by X-ray crystallography. The reactivity of these complexes was tested by the reactions of [Pt{2,4-(MeO)2C6H2C(H)NCH2CH2NMe2}–(Me)] with tertiary phosphines and diphosphines. In the latter case, dinuclear and mononuclear platinum complexes were synthesized, with bridging or chelating diphosphine ligands, respectively, depending on the complex/diphosphine molar ratio used. The reaction of the related potentially hexadentate ligand 1,4-[Me2NCH2CH2N(H)C]2C6H4 with [PtMe2(COD)] gave the metallated compound [(Me)Pt{Me2NCH2CH2N(H)C}C6H2{C(H)N–CH2CH2NMe2}Pt(Me)] with five fused rings.

Cylometallated semicarbazone complexes of palladium(II). Crystal and molecular structure of [{Pd[C6H4C(Et)NN(H)C(O)NH2]}2(μ-Ph2P(CH2)3PPh2)][ClO4]2

Abstract Treatment of the semicarbazones 4-MeC6H4C(Me)NN(H)C(O)NH2 a, 3,4-Me2C6H3C(Me)NN(H)C(O)NH2 b and C6H5C(Et)NN(H)C(O)NH2 c, gave the [C,N,O] cyclometallated compounds [Pd{4-MeC6H3C(Me)NN(H)C(O)NH2}(Cl)] 1a, [Pd{3,4-Me2C6H2C(Me)NN(H)C(O)NH2}(Cl)] 1b and [Pd{C6H4C(Et)NN(H)C(O)NH2}(Cl)] 1c, after CH activation. Treatment of compounds 1a, 1b, and 1c with silver perchlorate followed by treatment with tertiary diphosphine ligands gave the dinuclear [C,N,O] cyclometallated compounds [{Pd[4-MeC6H3C(Me)NN(H)C(O)NH2]}2(μ-L)][ClO4]2 2a–7a, [{Pd[3,4-Me2C6H2C(Me)NN(H)C(O)NH2]}2(μ-L)][ClO4]2 2b–7b, [{Pd[C6H4C(Et)NN(H)C(O)NH2]}2(μ-L)][ClO4]2 2c–7c, [L=Ph2P(CH2)4PPh2 (dppb), Ph2P(CH2)3PPh2 (dppp), Ph2P(CH2)2PPh2 (dppe), trans-Ph2PCHCHPPh2 (trans-dppe), Ph2PC(CH2)PPh2 (vdpp) and Ph2PCH2PPh2 (dppm)] as 1:2 electrolytes. Reaction of 1a and 1c with diphosphines gave the dinuclear [C,N] cyclometallated compounds [{Pd[4-MeC6H3C(Me)NN(H)C(O)NH2](Cl)}2(μ-L)] 8a, 9a, [{Pd[C6H4C(Et)NN(H)C(O)NH2](Cl)}2(μ-L)] 8c, 9c, [L=Ph2P(CH2)3PPh2 (dppp) and Ph2P(CH2)4PPh2 (dppb)]. The complexes were characterised by their elemental analysis (C,H,N) and by IR and 31P{1H} and 1H-NMR data, and [{Pd[C6H4C(Et)NN(H)C(O)NH2]}2(μ-Ph2P(CH2)3PPh2)][ClO4]2 (3c) was characterised crystallographically.

Synthesis and characterization of cyclometallated complexes of palladium(II) and manganese(I) with bidentate Schiff bases

Treatment of N,N-isophthalylidenebis(cyclohexylamine), 1,3-(CyNCH)2C6H4 (L2) (Cy = cyclohexyl) with palladium(II) acetate in glacial acetic acid gave after column chromatography the monocyclometallated dimer complex [{Pd[3-(CHO)C6H3C(H)NCy](O2CMe)}2] (1) with a free formyl group on each phenyl ring, and a mixture of 1 with the doubly cyclometallated complex [Pd{3-(CyNCH)C6H3C(H)NCy}(O2CMe)] (2). Treatment of 1 with cyclohecylamine gave the corresponding dimer complex [{Pd[3-(CyNCH)C6H3C(H)NCy]O2CMe)}2] (17 with an uncoordinated CN group on each phenyl ring. Treatment of 1 and 2 with aqueous NaX gave the dimer complexes [{Pd[3-(CHO)C6H3C(H)NCy](X)}2] (3: X = Cl; 4 X = Br; 5: X = I) and a mixture of 3, 4 or 5 with the doubly cyclometallated complex [{Pd[3-(CyNCH)C6H3C(H)NCy}(X)] (6: X = Cl; 7: X = Br; 8: X = I), respectively. The dicyclometallated iodo complex 8 was isolated pure. Treatment of 3, 4 or 5 with cyclohexylamine in a 1 : 2 or 1 : 4 molar ratio gave the cyclometallated complexes [{Pd[3-(CHO)C6H3C(H)NCy}(X)(NH2Cy)] (9: X = Cl; 10: X = Br; 11: X = I) and [{Pd[3-(CyNCH)C6H3C(H)NCy}(X)(NH2Cy)] (12: X = Cl; 13: X = Br; 14: X = I), respectively; the last three compounds each contain an uncoordinated C  N group. The corresponding bromo and iodo analogues were made similarly. Treatment of 3, 4 or 5 with thallium cyclopentadienyl or thallium acetylacetonate gave the mononuclear complexes [{Pd[3-(CHO)C6H3C(H)NCy}(C5H5)] (15) and [{Pd[3-(CHO)C6H3C(H)NCy}(H3CCOCHCOCH3)] (16), respectively. Treatment of L2 with MnMe(CO)5 in a 1 : 1 molar ratio gave the monocyclometallated complex [(OC)4Mn{3-(CHO)C6H3C(H)NCy}] (18) by cleavage of one CN bond, whereas treatment of L2 with MnMe(CO)5 in a 1 : 1.2 molar ratio produced a mixture of the doubly cyclometallated complex 19 and the monocyclometallated complex 20 without cleavage of the C  N bond. Treatment of N,N-terephthalylidenebis(cyclohexylamine), 1,4-(CyNCH)2C6H4 (L1) (Cy = cyclohexyl), with MnMe(CO)5 in a 1 : 1.2 molar ratio gave a mixture of the monocyclometallated compound [(OC)4Mn{4-(CHO)C6H3C(H)NCy}] (22) and the monocyclometallated compound [(OC)4Mn{4-(CyNCH)C6H3C(H)NCy}] (23); compound 22 was isolated in a pure state.

Novel structures of cyclometallated complexes of palladium(II) derived from terdentate ligands. Crystal and molecular structure of [Pd{C6H4C(H)NCH2CH2CH2NMe2}(X)] (X=Cl, Br, I)

Abstract Treatment of N-(2-chlorobenzylidene)-N,N-dimethyl-1,3-propanediamine (1) and N-(2-bromo-3,4-(MeO)2-benzylidene)-N,N-dimethyl-1,3-propanediamine (20) with tris(dibenzylideneacetone)dipalladium(0) in toluene gave the mononuclear cyclometallated complexes [Pd{C6H4C(H)NCH2CH2CH2NMe2}(Cl)] (2) and [Pd{3,4-(MeO)2C6H2C(H)NCH2CH2CH2NMe2}(Br)] (21), respectively, via oxidative addition reaction with the ligand as a C,N,N terdentate ligand. Reaction of 2 with sodium bromide or iodide in an acetone–water mixture gave the cyclometallated analogues of 2, [Pd{C6H4C(H)NCH2CH2CH2NMe2}(Br)] (3) and [Pd{C6H4C(H)NCH2CH2CH2NMe2}(I)] (4), by halogen exchange. The X-ray crystal structures of 2, 3 and 4 were determined and discussed. Treatment of 2, 3, 4 and 21 with tertiary monophosphines in acetone gave the mononuclear cyclometallated complexes [Pd{C6H4C(H)NCH2CH2CH2NMe2}(L)(X)] (6: L=PPh3, X=Cl; 7: L=PPh3, X=Br; 8: L=PPh3, X=I; 9: L=PMePh2, X=Cl; 10: L=PMe2Ph, X=Cl) and [Pd{3,4-(MeO)2C6H2C(H)NCH2CH2CH2NMe2}(L)(Br)] (22: L=PPh3; 23: L=PMePh2; 24: L=PMe2Ph). A fluxional behaviour due to an uncoordinated CH2CH2CH2NMe2 could be determined by variable temperature NMR spectroscopy. Treatment of 2, 3 and 4 with silver trifluoromethanesulfonate followed by reaction with triphenylphosphine gave the mononuclear complex [Pd{C6H4C(H)NCH2CH2CH2NMe2}(PPh3)][F3CSO3] (11) where the Pd–NMe2 bond was retained. Reaction of 2, 3 and 4 with ditertiary diphosphines in a cyclometallated complex–diphosphine 2:1 molar ratio gave the binuclear complexes [{Pd[C6H4C(H)NCH2CH2CH2NMe2](X)}2(μ-L–L)][L–L=PPh2(CH2)4PPh2(dppb) (13, X=Cl; 14, X=Br; 15, X=I; L–L=PPh2(CH2)5PPh2(dpppe): 16, X=Cl; 17, X=Br; 18, X=I) with palladium–NMe2 bond cleavage. Treatment of 2, 3 and 4 with ditertiary diphosphines, in a cyclometallated complex–diphosphine 2:1, molar ratio and AgSO3CF3 gave the binuclear cyclometallated complexes [{Pd[C6H4C(H)NCH2CH2CH2NMe2]}2(μ-L–L)][F3CSO3]2 (11: L–L=PPh2(CH2)4PPh2(dppb), X=Cl; 12: L–L=PPh2(CH2)5PPh2 (dpppe), X=Cl). Reaction of 2 with the ditertiary diphosphine cis-dppe in a cyclometallated complex–diphosphine 1:1 molar ratio followed by treatment with sodium perchlorate gave the mononuclear cyclometallated complex [Pd{C6H4C(H)NCH2CH2CH2NMe2}(cis-PPh2CHCHPPh2–P,P)][ClO4] (19).

Cyclopalladated compounds derived from a [C,N,S] terdentate ligand: synthesis, characterization and reactivity. Crystal and molecular structures of [Pd{2-ClC6H3C(H)NCH2CH2SMe}(Cl)] and [{Pd[2-ClC6H3C(H)NCH2CH2SMe]}2{μ-Ph2P(CH2)4PPh2}][CF3SO3]2

Treatment of the Schiff base 2-ClC6H4C(H)NCH2CH2SMe, 1, with palladium(II) acetate in dry toluene gave the mononuclear cyclometallated complex [Pd{2-ClC6H3C(H)NCH2CH2SMe}(O2CMe)], 2. Reaction of 2 with aqueous sodium chloride gave [Pd{2-ClC6H3C(H)NCH2CH2SMe}(Cl)], 3, after a metathesis reaction. The X-ray crystal structure of 3 was determined and shows that the palladium atom is bonded to four different donor atoms: C, N, S and Cl. Treatment of 3 with triphenylphosphine in acetone gave the mononuclear cyclometallated complex [Pd{2-ClC6H3C(H)NCH2CH2SMe}(Cl)(PPh3)] with cleavage of the Pd–S bond. However, treatment of 3 with silver triflate and triphenylphosphine gave [Pd{2-ClC6H3C(H)NCH2CH2SMe}(PPh3)][CF3SO3], 10, in which the Pd–S bond is retained. Reaction of 3 with the diphosphines dppm, dppb or dppf in a 2 : 1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[2-ClC6H3C(H)NCH2CH2SMe](Cl)}2{μ-Ph2P(CH2)nPPh2}], (n=1, 5; n=4, 6), and [{Pd[2-ClC6H3C(H)NCH2CH2SMe](Cl)}2(μ-Ph2PC5H4FeC5H4PPh2)], 7. Treatment of 3 with dppb in a 2 : 1 molar ratio and AgCF3SO3 gave the dinuclear cyclometallated complex [{Pd[2-ClC6H3C(H)NCH2CH2SMe]}2{μ-Ph2P(CH2)4PPh2}][CF3SO3]2, 11, which was characterized by X-ray crystal structure analysis. Reaction of 3 with dppe in a 1 : 1 molar ratio and sodium perchlorate gave the mononuclear complex [Pd{2-ClC6H3C(H)NCH2CH2SMe}{Ph2P(CH2)2PPh2-P,P}][ClO4], 8. Treatment of 3 with bis(2-diphenylphosphinoethyl)phenylphosphine in a 1 : 1 molar ratio, followed by treatment with sodium perchlorate gave [Pd{2-ClC6H3C(H)NCH2CH2SMe}{(Ph2PCH2CH2)2PPh-P,P,P}][ClO4], 9, in which the triphosphine is bonded to the palladium atom through the three phosphorus atoms.