Miguel Gayoso

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).

Cyclometallated complexes of palladium(II) with the diphosphines trans-Ph2 PCHCHPPh2, cis-Ph2PCHCHPPh2 and Ph2P(CH2)4PPh2. The X-ray crystal structure of [{Pdd[2,4-Me2C6H2C(H)NCy]}2 (μ-Ph2P(CH2)4PPh2)(μ-Cl)2]

Abstract Treatment of 2,4-Me 2 C 6 H 3 C(H)NCy ( a ) or 2,3-(MeO) 2 C 6 H 3 C(H)NCy ( b ) (Cy  cyclohexyl) with palladium(II) acetate gave the cyclometallated acetato-bridged complexes 1a and 1b . These were converted into the analogous halide-bridged complexes by reaction with NaX ( 2a , 2b , X  Cl; 3a , 3b , X  Br; 4a , 4b , X  I). The halide-bridged dimers react: (a) with trans -Ph 2 PCHCHPPh 2 ( trans -dppe) and Ph 2 P(CH 2 ) 4 PPh 2 (dppb) in a dimer/diphosphine 1:1 molar ratio to give the dinuclear phosphine-bridged complexes 5a – 7a , 5b – 7b ( trans -dppe) and 8a – 10a , 8b – 10b (dppb); and (b) with cis -Ph 2 PCHCHPPh 2 ( cis -dppe) or Ph 2 P(CH 2 ) 4 PPh 2 (dppb), in a dimer/diphosphine 1:2 molar ratio, and NH 4 PF 6 , to give the mononuclear cyclometallated species 11a , 11b ( cis -dppe), or 12a and 12b (dppb). The structure of 8a is described. This is the first structurally characterised dinuclear palladium (II) complex with two cyclometallated moieties bounded through a diphosphine ligand. The crystals are monoclinic, space group P 2 1 / n with a = 1084.1(7), b = 3067.7(28), c = 1181.9(10) pm, β = 114.22(6)°, U 3.585(5) nm 3 , Z = 2, R = 0.0731 and R w = 0.0602 for 3970 independent reflections.

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.

Cyclometallated complexes of bis(N-benzylidene)-1,4-phenylenediamines. Synthesis and crystal structure of [1,4-{Pd[2,3,4-(MeO)3C6HC(H)=N](Br)}2C6H4]2: a novel tetranuclear cyclometallated palladium(II) complex

Abstract Treatment of 1,4-{2,3,4-(MeO)3C6H2C(H)=N-}2C6H, (a) or 1,4-{4,5-(OCH2O)C6H 3C(H)=N-}2-C6H4 (b) with palladium(II) acetate gave the cyclometallated acetato-bridged complexes [1,4-{ Pd [2,3,4-(MeO) 3 C 6 HC(H)=N ](O2CMe)}2C6H4]n (1a) and [1,4- Pd[4,5-(OCH 2 O)C 6 H 2 C(H)=N ](O2CMe)}2-C6H4]n (1b). These were converted into the analogous halide-bridged complexes by treatment with NaX (2a, 2b X = Cl; 3a, 3b X = Br). Reaction of a or b with PdCl2 also affords the chloro-bridged complexes 2a and 2b, which reacted with LiBr to give the bromo-bridged complexes 3a and 3b. The structure of 3a is described. This is the first example of a structurally characterized tetranuclear cyclometallated bromo-bridged palladium(II) complex. Crystals are triclinic, space group P 1 , with a 1109.1(4), b 1181.5(4), c 1481.5(5) pm, α 77.33(3), β 80.04(3), γ 82.50(3), U 1.857(1) nm3, Z = 1, R = 0.0558 and RW = 0.0610, for 3871 independent reflections with I > 2.0σ-(I). The structure is a centrosymmetric tetranuclear palladium(II) dimer with symmetrically bridging bromine atoms and non-bonding Pd ⋯ Pd distance of 366.2(5) pm.

Cyclometallation&—III. Regioselectivity in Pd(II) Cyclometallated complexes

Abstract Cyclometallated complexes derived from organic ligands where two initial metallation sites are present have been synthesized. The preferred palladation position is discussed on the basis of electronic and steric effects, and the regioselectivity of the cyclometallation is characterized by means of IR and 1 H NMR spectroscopy. The spectral studies show that the less favored position is not attached to the metal atom. Acetato- and halogeno-bridged dimers, as well as phosphine monomers derived from the latter, have been obtained and studied by spectroscopical methods.

Dinuclear cyclometallated complexes of PdII with diphosphines. X-ray crystal structure of [1,4-{Pd[2,4-(MeO) 2C6H2C(H)=N]}2- C6H4{Ph2P(CH2)3PPh2−P,P}2][PF6]2

Treatment of the cyclometallated halide-bridged complexes [1,4-{Pd[2,3,4-(MeO)3C6HC(H)=N](X)}2C6H4]2 (1a, 2a), [1,4-{Pd[2,4-(MeO)2C6H2C(H)=N](X)}2C6H4]2 (1b, 2b), [1,4-{Pd[3-(Me-4-MeOC6H2C(H)=N](X)}2C6H4]2 (1c, 2c), [1,4-{Pd[4,5-(OCH2O)C6H2C(H)=N](X)}2C6H4]2 (1d, 2d), (X = Cl, Br) with ditertiary diphosphines in a complex/diphosphine 1:4 molar ratio and ammonium hexafluorophosphate gave the dinuclear cyclometallated complexes [1,4-{Pd[2,3,4-(MeO)3C6HC(H)N]}2C6H4(LL)2][PF6]2[LL  Ph2PCH(CH)3)PPh2, Ph2P(CH2)2PPh2, 3a, 4a], [1,4-{Pd[2,4-(MeO)2C6H2C(H)=N]}2C6H4(LL)2][PF6]2[LL  Ph2PCH(CH3)PPh2, Ph2P(CH2)2PPh2, 3b, 4b] [1,4-{Pd[3-(Me-4-MeOC6H2C(H)=N]}C6H4(LL)2][PF6]2[LL  Ph2PCH(CH3)PPh2, Ph2P(CH2)nPPh2, n = 2, 3, 3c, 4c, 5c], [1,4-{Pd[4,5-(OCH2O)C6H2C(H)=N]}2C6H4(LL)2] [PF6]2[LL = Ph2PCH(CH3)PPh2, Ph2P(CH2)nPPh2, n = 2, 3, 4, 3d, 4d, 5d, 6d]. The influence of ring size on the phosphorus chemical shift is discussed. The compounds were characterized by microanalysis (C, H, N), IR and 31P-{1H} and 1H NMR spectroscopy. The structure of the dinuclear cyclometallated palladium(II) complex [1,4-{Pd[2,4-(MeO)2C6H2C(H)=N]}2C6H4{Ph2P(CH2)3 PPh2−PP}2][PF6]2 is described. There are two different crystallographic molecules per asymmetric unit.

Cyclometallation, part II. I.r. and1H N.m.r. studies of palladium(II) compounds with substitutedN-(benzylidene)amines

SummaryNew cyclometallated complexes of palladium containing substitutedN-(benzylidene)amines have been prepared and characterized. Palladium(II) acetate is used to make the acetato-bridged dimers, which undergo metathetical reactions to give the halo-bridged dimers. These when treated with PPh3 or P(C6H11)3 in a 1∶2 molar ratio yield the phosphine monomers. I.r. and1H n.m.r. studies show that palladium is coordinated through nitrogen, and also reveal the disposition of the halogen and phosphine ligands in the monomeric complexes.

Cyclometallated complexes of palladium(II) with 1-methyl-2-phenylimidazole and tertiary diphosphines. Crystal and molecular structure of [Pd[o-C6H4C=NC(H)=C(H)NMe](Ph2PCH(Me)PPh2-P,P)][PF6]

Abstract Treatment of Pd(AcO) 2 with 1-methyl-2-phenylimidazole, and subsequent treatment with sodium chloride or sodium bromide gave the corresponding halide-bridged cyclometallated complexes [Pd o -C 6 H 4 C=NC(H)=C(H)NMe( μ -X)] 2 ( 2 , X = Cl; 3 , X = Br). Complexes 2 and 3 react with tertiary diphosphines in a 1:1 molar ratio to give dinuclear cyclometallated compounds with bridging diphosphine and halogen ligands [Pd o -C 6 H 4 C=NC(H)=C(H)NMe( μ -L-L)( μ -X)]X ( 4–9 ) or with only bridging diphosphine ligands [Pd o -C 6 H 4 C=NC(H)=C(H)NMe( μ -L-L)(X) 2 ] ( 10–17 ), [X = Cl, Br; L-L = Ph 2 PCH 2 PPh 2 (dppm), Ph 2 PC(=CH 2 )PPh 2 (vdpp), Ph 2 PCH(CH 3 )PPh 2 (1,1-dppe), trans -Ph 2 P(CH=CH)PPh 2 ( trans -dppe), Ph 2 P(CH 2 ) 2 PPh 2 (dppe), Ph 2 P(CH 2 ) 3 PPh 2 (dppp), Ph 2 P(CH 2 ) 4 PPh 2 (dppb), as appropriate]. When the reaction is carried out in a 1:2 molar ratio and in the presence of NH 4 PF 6 or NaClO 4 , mononuclear cyclometallated compounds with a chelating diphosphine ligand are obtained [Pd o -C 6 H 4 C=NC(H)=C(H)NMe(L-L-P,P)][Y] ( 18–27 ) [Y = PF 6 , ClO 4 ; L-L = Ph 2 PCH 2 PPh 2 (dppm), Ph 2 PC(=CH 2 )PPh 2 (vdpp), Ph 2 PCH(CH 3 )PPh 2 (1,1-dppe), Ph 2 PN(CH 3 )PPh 2 (dppma), cis -Ph 2 P(CH=CH)PPh 2 ( cis -dppe), Ph 2 P(CH 2 ) 2 PPh 2 (dppe), Ph 2 P(CH 2 )PPh 2 (dppp), Ph 2 P(CH 2 ) 4 PPh 2 (dppb)]. Compounds 18–22 and 25–27 could also be obtained by reaction of complexes 4–17 with the appropriate diphosphine and NH 4 PF 6 or NaClO 4 . The diphosphines dppma and cis -dppe failed to behave as bridging ligands and only gave mononuclear compounds. The complexes were characterized by their elemental analysis (C, H, N) and by IR and 31 P- 1 H and 1 H NMR data. The X-ray crystal structure of complex 22 is described.