Mono- and dinuclear cobalt complexes with chelating or bridging bidentate P,N phosphino- and phosphinito-oxazoline ligands: synthesis, structures and catalytic ethylene oligomerisation

Cobalt(ii) complexes of the type [CoCl(2)(P,N)], where P,N represents a heterobidentate phosphino- or phosphinito-oxazoline-type ligand, have been synthesised and characterised by infrared spectroscopy and elemental analysis. Their molecular structures were established by single-crystal X-ray diffraction in the solid state. Whereas the phosphino-oxazoline complex [CoCl(2){Ph(2)PCH(2)ox(Me2)}] (Ph(2)PCH(2)ox(Me2) = 2-[(diphenylphosphanyl)-methyl]-4,4-dimethyl-4,5-dihydro-oxazole) () and the phosphinito-oxazoline complexes [CoCl(2){Ph(2)POCH(2)ox(Me2)}] (Ph(2)POCH(2)ox(Me2) = 1-[4,4-dimethyl-2{1-oxy(diphenylphosphino)-1-methyl}]-4,5-dihydro-oxazole) () and [CoCl(2){Ph(2)POCMe(2)ox(Me2)}] (Ph(2)POCMe(2)ox(Me2) = 1-[4,4-dimethyl-2- [1-oxy(diphenylphosphino)-1-methylethyl]]-4,5-dihydrooxazole) () are mononuclear, the phosphino-oxazoline complexes [CoCl(2){micro-i-Pr(2)PCH(2)ox}](2) (i-Pr(2)PCH(2)ox = 2-[(diisopropyl-phosphanyl)-methyl]-4,5-dihydro-oxazole) () and [CoCl(2){micro-Ph(2)PCH(2)ox}](2) (Ph(2)PCH(2)ox = 2-[(diphenyl-phosphanyl)-methyl]-4,5-dihydro-oxazole) () are dinuclear compounds and contain two bridging phosphino-oxazoline ligands which form a 10-membered ring. In the course of this work, the zwitterionic complex [CoCl(3){Ph(2)PCH(2)C(O)OCH(2)CMe(2)NH(3)] () was obtained and characterised by X-ray diffraction in which the oxazoline ring has been opened. Air-oxidation of the phosphine function of the mononuclear P,N chelate complex yielded the blue N,O-bridged, centrosymmetric dinuclear complex [[upper bond 1 start]CoCl(2){micro-OPPh(2)CH(2)[lower bond 1 start]C[double bond, length as m-dash]N[upper bond 1 end]CMe(2)CH(2)O[lower bond 1 end]}](2) () which contains a 12-membered ring. All these complexes are paramagnetic and their magnetic moments in solution were measured by the Evans method. Complexes were evaluated in the catalytic oligomerisation of ethylene with AlEtCl(2) or methylaluminoxane (MAO) as cocatalysts and provided moderate activities. In the presence of AlEtCl(2) (6-14 equiv.), the selectivities for ethylene dimers were higher than 92% and complex showed the highest turnover frequency with 14 equiv. of AlEtCl(2). When MAO was used as cocatalyst, the catalytic activities were similar to those with AlEtCl(2) but significant amounts of C(6)-C(12) oligomers were produced.     

Ni(II), Pd(II) and Pt(II) complexes of PNP and PSP tridentate amino-phosphine ligands

The ligands D((CH(2))(2)NHPiPr(2))(2) (D = NH 1, S 2) react with (dme)NiCl(2) or (PhCN)(2)MCl(2) (M = Pd, Pt) to give complexes of the form [D((CH(2))(2)NHPiPr(2))(2)MX]X (X = Cl, I; M = Ni, Pd, Pt) which were converted to corresponding iodide derivatives by reaction with Me(3)SiI. Reaction of 1 or 2 with (COD)PdMeCl affords facile routes to [κ(3)P,N,P-NH((CH(2))(2)NHPiPr(2))(2)PdMe]Cl (8a) and [κ(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)PdMe]Cl (9a) in high yields. An alternative synthetic approach involves oxidative addition of MeI to a M(0) precursor yielding [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)NiMe]I (10), [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MMe]I (M = Pd 8b Pt 11) and [κ(3)P,S,P-S(CH(2)CH(2)NHPiPr(2))(2)MMe]I (M = Pd 9b, Pt 12). Alternatively, use of NEt(3)HCl in place of MeI produces the species [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MH]X (X = Cl, M = Ni 13a, Pd 14a, Pt 16a). The analogs containing 2; [κ(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)MH]X (M = Pd, X = PF(6)15: M = Pt, X = Br, 17a, PF(6)17b) were also prepared in yields ranging from 74-93%. In addition, aryl halide oxidative addition was also employed to prepare [κ(3)P,N,P-HN(CH(2)CH(2)NHPiPr(2))(2)MC(6)H(4)F]Cl (M = Ni 18, Pd 19) and [κ(3)P,S,P-S((CH(2))(2)NHPiPr(2))(2)Pd(C(6)H(4)F)]Cl (20). Crystal structures of 3a, 4a, 5a, 6a, 8a, 9a, 14b and 16b are reported.     

On the reactivity toward ketones of new methyl amino complexes of Rh(III) and Ag(I). Synthesis of ortho-rhodiated acetophenone methyl imine complexes

MeNH(2) reacts with silver salts AgX (2:1) to give [Ag(NH(2)Me)(2)]X [X = TfO = CF(3)SO(3) (1.TfO) and ClO(4) (1.ClO(4))]. Neutral mono(amino) Rh(III) complexes [Rh(Cp*)Cl(2)(NH(2)R)] [R = Me (2a), To = C(6)H(4)Me-4 (2b)] have been prepared by reacting [Rh(Cp*)Cl(mu-Cl)](2) with RNH(2) (1:2). The following cationic methyl amino complexes have also been prepared: [Rh(Cp*)Cl(NH(2)Me)(PPh(3))]TfO (3.TfO), from [Rh(Cp*)Cl(2)(PPh(3))] and 1.TfO (1:1); [Rh(Cp*)Cl(NH(2)R)2]X, where R = Me, X = Cl, (4a.Cl), from [Rh(Cp*)Cl(mu-Cl)]2 and MeNH2 (1:4), or R = Me, X = ClO4 (4a.ClO4), from 4a.Cl and NaClO4 (1:4.8), or R = To, X = TfO (4b.TfO), from [Rh(Cp*)Cl(mu-Cl)](2), ToNH(2) and TlTfO (1:4:2); [Rh(Cp*)(NH(2)Me)(tBubpy)](TfO)(2) (tBubpy = 4,4'-di-tert-butyl-2,2'-bipyridine, 5.TfO), from 2a, TlTfO and tBubpy (1:2:1); [Rh(Cp*)(NH(2)Me)(3)](TfO)2 (6.TfO) from [Rh(Cp*)Cl(mu-Cl)](2) and 1.TfO (1:4). 2-6 constitute the first family of methyl amino complexes of rhodium. 1 and 4a.ClO(4) react with acetone to give, respectively, the methyl imino complexes [Ag{N(Me)=CMe(2)}()]X [X = TfO (7.TfO), ClO(4) (7.ClO(4))], and [Rh(Cp*)Cl(Me-imam)]ClO(4) [8.ClO(4), Me-imam = N,N'-N(Me)=C(Me)CH(2)C(Me)(2)NHMe]. 7.X (X = TfO, ClO(4)) are new members of the small family of methyl acetimino complexes of any metal whereas 8.ClO4 results after a double acetone condensation to give the corresponding bis(methyl acetimino) complex and an aldol-like condensation of the two imino ligands. The acetimino complex [Ag(NH=CMe(2))(2)]ClO(4) reacts with [Rh(Cp*)Cl(imam)]ClO(4) [1:1, imam = N,N'-NH=C(Me)CH(2)C(Me)(2)NH(2)] to give [Rh(Cp*)(imam)(NH=CMe(2))](ClO(4))(2) (9a.ClO(4)). 8.ClO(4) reacts with AgClO(4) (1:1) in MeCN to give [Rh(Cp*)(Me-imam)(NCMe)](ClO(4))2 (9b.ClO(4)), which in turn reacts with XyNC (Xy = C(6)H(3)Me(2)-2,6) or with MeNH(2) (1:1) to give [Rh(Cp*)(Me-imam)L](ClO(4))(2) [L = XyNC (9c.ClO(4)), MeNH(2) (9d.ClO(4))]. 6.TfO reacts with acetophenone to give [Rh(Cp*){C,N-C(6)H(4)C(Me)=N(Me)-2}(NH(2)Me)]TfO (10a.TfO), the first complex resulting from such a condensation and cyclometalation reaction. In turn, 10a.TfO reacts with isocyanides RNC (1:1) at room temperature to give [Rh(Cp*){C,N-C(6)H(4)C(Me)=NMe-2}(CNR)]TfO [R = tBu (10b.TfO), Xy (10c.TfO)], or 1:12 at 60 degrees C to give [Rh(Cp*){C,N-C(=NXy)C(6)H(4)C(Me)=N(Me)-2}(CNXy)]TfO (11.TfO). The crystal structures of 9a.ClO(4).acetone-d6, 9c.ClO(4), and 10a.TfO have been determined.     

Synthesis and reactivity of Ir(I) and Ir(III) complexes with MeNH2, Me2C=NR (R = H, Me), C,N-C6H4{C(Me)=N(Me)}-2, and N,N'-RN=C(Me)CH2C(Me2)NHR (R = H, Me) ligands

Complexes [Ir(Cp*)Cl(n)(NH2Me)(3-n)]X(m) (n = 2, m = 0 (1), n = 1, m = 1, X = Cl (2a), n = 0, m = 2, X = OTf (3)) are obtained by reacting [Ir(Cp*)Cl(mu-Cl)]2 with MeNH2 (1:2 or 1:8) or with [Ag(NH2Me)2]OTf (1:4), respectively. Complex 2b (n = 1, m = 1, X = ClO 4) is obtained from 2a and NaClO4 x H2O. The reaction of 3 with MeC(O)Ph at 80 degrees C gives [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(NH2Me)]OTf (4), which in turn reacts with RNC to give [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(CNR)]OTf (R = (t)Bu (5), Xy (6)). [Ir(mu-Cl)(COD)]2 reacts with [Ag{N(R)=CMe2}2]X (1:2) to give [Ir{N(R)=CMe2}2(COD)]X (R = H, X = ClO4 (7); R = Me, X = OTf (8)). Complexes [Ir(CO)2(NH=CMe2)2]ClO4 (9) and [IrCl{N(R)=CMe2}(COD)] (R = H (10), Me (11)) are obtained from the appropriate [Ir{N(R)=CMe2}2(COD)]X and CO or Me4NCl, respectively. [Ir(Cp*)Cl(mu-Cl)]2 reacts with [Au(NH=CMe2)(PPh3)]ClO4 (1:2) to give [Ir(Cp*)(mu-Cl)(NH=CMe2)]2(ClO4)2 (12) which in turn reacts with PPh 3 or Me4NCl (1:2) to give [Ir(Cp*)Cl(NH=CMe2)(PPh3)]ClO4 (13) or [Ir(Cp*)Cl2(NH=CMe2)] (14), respectively. Complex 14 hydrolyzes in a CH2Cl2/Et2O solution to give [Ir(Cp*)Cl2(NH3)] (15). The reaction of [Ir(Cp*)Cl(mu-Cl)]2 with [Ag(NH=CMe2)2]ClO4 (1:4) gives [Ir(Cp*)(NH=CMe2)3](ClO4)2 (16a), which reacts with PPNCl (PPN = Ph3=P=N=PPh3) under different reaction conditions to give [Ir(Cp*)(NH=CMe2)3]XY (X = Cl, Y = ClO4 (16b); X = Y = Cl (16c)). Equimolar amounts of 14 and 16a react to give [Ir(Cp*)Cl(NH=CMe2)2]ClO4 (17), which in turn reacts with PPNCl to give [Ir(Cp*)Cl(H-imam)]Cl (R-imam = N,N'-N(R)=C(Me)CH2C(Me)2NHR (18a)]. Complexes [Ir(Cp*)Cl(R-imam)]ClO4 (R = H (18b), Me (19)) are obtained from 18a and AgClO4 or by refluxing 2b in acetone for 7 h, respectively. They react with AgClO4 and the appropriate neutral ligand or with [Ag(NH=CMe2)2]ClO4 to give [Ir(Cp*)(R-imam)L](ClO4)2 (R = H, L = (t)BuNC (20), XyNC (21); R = Me, L = MeCN (22)) or [Ir(Cp*)(H-imam)(NH=CMe2)](ClO4)2 (23a), respectively. The later reacts with PPNCl to give [Ir(Cp*)(H-imam)(NH=CMe2)]Cl(ClO4) (23b). The reaction of 22 with XyNC gives [Ir(Cp*)(Me-imam)(CNXy)](ClO4)2 (24). The structures of complexes 15, 16c and 18b have been solved by X-ray diffraction methods.     

Concise syntheses of tridentate PNE ligands and their coordination chemistry with palladium(II) : a solution- and solid-state study

A straightforward methodology for the high-yielding synthesis of the di-functionalised phosphines {Ph2P(CH2)2NC4H8E, E = NMe (1), O (2), S (3)}via base-catalysed Michael addition is described. Reaction of the functionalised tertiary phosphines 1-3 with PdCl2(MeCN)2 affords complexes in which the ligands are bound in a tridentate fashion, namely [PdCl(kappa3-PNE)]Cl (6a, 8) as the predominant products. A kappa2-PN coordination mode was also identified crystallographically for ligand following its reaction with PdCl2(MeCN)2, which afforded [PdCl2(-kappa2-PN)] (6b) in ca. 5% yield. Conductivity studies of solutions of 6a are consistent with an ionic formulation, however the poor solubility of and precluded their study in a similar fashion. Analysis of bulk samples of [PdCl2(1)] (6) and [PdCl2(3)] (8) by 15N and 31P NMR spectroscopy in the solid state as consistent with exclusive tridentate binding of the PNE ligands. An X-ray crystallographic study has probed the coordination of in the unusual salt [PdCl(-kappa3-PNN)]2[Mg(SO4)2(OH2)4] (10) prepared by treating a methanolic solution of with excess MgSO4. No data could be obtained to support the transformation of 6a into 6b on addition of excess chloride. In contrast, 6a reacts regioselectively with the water-soluble phosphine Cy2PCH2CH2NMe3Cl to afford the cis-diphosphine complex cis-[PdCl(Cy2PCH2CH2NMe3Cl)(1-kappa2-PN)]Cl2 (9). Reaction of 1 with PdCl(Me)(COD) results in the formation of the kappa2-PN dichloride complex [PdCl(Me)(1-kappa(2)-PN)] (11). Attempts to prepare [Pd(Me)(MeCN)(-kappa2-PN)][PF6] (12) through reaction of 11 with NaPF6 in MeCN led to decomposition. Treatment of PdMe2(TMEDA) with 1 at low temperature initially affords [PdMe2(1-kappa2-NN)], which isomerises to afford [PdMe(2)(1-kappa(2)-PN)] (13); at temperatures greater than 10 degrees C complex 13 decomposes rapidly.     

Nickel and iron complexes with N,P,N-type ligands: synthesis, structure and catalytic oligomerization of ethylene

The N,P,N-type ligands bis(2-picolyl)phenylphosphine (), bis(4,5-dihydro-2-oxazolylmethyl)phenylphosphine (), bis(4,4-dimethyl-2-oxazolylmethyl)phenylphosphine () and bis(2-picolyloxy)phenylphosphine () were used to synthesize the corresponding pentacoordinated Ni(ii) complexes [Ni{bis(2-picolyl)phenylphosphine}Cl(2)] (), [Ni{bis(4,5-dihydro-2-oxazolylmethyl)phenylphosphine}Cl(2)] (), [Ni{bis(4,4-dimethyl-2-oxazolylmethyl)phenylphosphine}Cl(2)] () and [Ni{bis(2-picolyloxy)phenylphosphine}Cl(2)] (), respectively. The hexacoordinated iron complexes [Fe{bis(2-picolyl)phenylphosphine}(2)][Cl(3)FeOFeCl(3)] (), [Fe{bis(4,5-dihydro-2-oxazolylmethyl)phenylphosphine}(2)][Cl(3)FeOFeCl(3)] () and the tetracoordinated complex [Fe{bis(4,4-dimethyl-2-oxazolylmethyl)phenylphosphine}Cl(2)] (abbreviated [FeCl(2)(NPN(Me2)-N,N)]) were prepared by reaction of FeCl(2).4H(2)O with ligands , respectively. The crystal structures of the octahedral complexes and , determined by X-ray diffraction, showed that two tridentate ligands are facially coordinated to the metal centre with a cis-arrangement of the P atoms and the dianion (mu-oxo)bis[trichloroferrate(iii)] compensates the doubly positive charge of the complex. The cyclic voltammograms of and showed two reversible redox couples attributed to the reduction of the dianion (Fe(2)OCl(6))(2-) (-0.24 V for and -0.20 V for vs. SCE) and to the oxidation of the Fe(ii) ion of the complex (0.67 V for and 0.52 V for vs. SCE). The cyclic voltammogram of [FeCl(2)(NPN(Me2)-N,N)] showed a reversible redox couple at -0.17 V vs. SCE assigned to the oxidation of the Fe(ii) atom and an irreversible process at 0.65 V. The complexes , and [FeCl(2)(NPN(Me2)-N,N)] have been evaluated in the catalytic oligomerization of ethylene with AlEtCl(2) or MAO as cocatalyst. The nickel complex proved to be the most active precatalyst in the series, with a turnover frequency (TOF) of 61 800 mol(C(2)H(4)) mol(Ni)(-1) h(-1) with 10 equiv. of AlEtCl(2) and 12 200 mol(C(2)H(4)) mol(Ni)(-1) h(-1) with 200 equiv. of MAO. Precatalysts and were the most selective in butenes, up to 90% with 6 equiv. of AlEtCl(2) and 89% with 2 equiv. of AlEtCl(2), respectively, and up to 92% butenes with 400 equiv. of MAO and 91% butenes with 200 equiv. MAO, respectively. The best selectivities for 1-butene were provided by and AlEtCl(2) (up to 31% with 6 equiv.) and with MAO (up to 72% with 200 equiv.). The iron complexes were not significantly active with AlEtCl(2) or MAO as cocatalyst.     

Stable, chloride-induced monohapto-bonding mode for an allyl ligand in a Pd(II) complex bearing a new bidentate phosphonite-oxazoline ligand

Bidentate ligands can lead to stable eta(1)-allyl complexes of Pd(II). A novel chelating phosphonite-oxazoline P,N ligand, abbreviated NOPO(Me2), has been prepared by reaction of 6-chloro-6H-dibenz[c,e][1,2]oxaphosphorin with the lithium alcoholate derived from 4,4-dimethyl-2-(1-hydroxy-1-methylethyl)-4,5-dihydrooxazole. Its reaction with [Pd(eta(3)-C(3)H(5))(micro-Cl)](2) afforded the new eta(1)-allyl Pd complex [PdCl(eta(1)-C(3)H(5))(NOPO(Me2))] 2 in 91% yield. This constitutes a still rare example of structurally characterized eta(1)-allyl Pd(II) complex. Chloride abstraction led to the corresponding cationic eta(3)-allyl complex [Pd(eta(3)-C(3)H(5))(NOPO(Me2))]PF(6) 3, which has also been characterized by X-ray diffraction. CO insertion into the Pd-C sigma-bond of the eta(1)-allyl ligand of 2 afforded the corresponding 3-butenoyl palladium complex [PdCl[C(O)C(3)H(5)](NOPO(Me2))] 4 under mild conditions, which supports the view that CO insertion into eta(3)-allyl palladium cationic complexes occurs via first coordination of the counterion to form a more reactive eta(1)-allyl intermediate.     

Nickel complexes with new bidentate P,N phosphinitooxazoline and -pyridine ligands: application for the catalytic oligomerization of ethylene

The phosphinitooxazoline 4,4-dimethyl-2-[1-oxy(diphenylphosphine)-1-methylethyl]-4,5-dihydrooxazole (9), the corresponding phosphinitopyridine ligands 2-ethyl-[1'-methyl-1'-oxy(diphenylphosphino)]pyridine (11) and 2-ethyl-6-methyl-[1'-methyl-1'-oxy(diphenylphosphino)]pyridine (12), which have a one-carbon spacer between the phosphinite oxygen and the heterocycle, and the homologous ligand 2-propyl-[2'-methyl-2'-oxy(diphenylphosphino)]pyridine (13), with a two-carbon spacer, were prepared in good yields. The corresponding mononuclear [NiCl(2)(P,N)] complexes 14 (P,N = 9), 15 (P,N = 11), and 16 (P,N = 12) and the dinuclear [NiCl(micro-Cl)(P,N)](2) 17 (P,N = 13) Ni(II) complex were evaluated in the catalytic oligomerization of ethylene. These four complexes were characterized by single-crystal X-ray diffraction in the solid state and in solution with the help of the Evans method, which indicated differences between the coordination spheres in the solution and the solid state. In the presence of methylalumoxane (MAO) or AlEt(3), only the decomposition of the Ni complexes was observed. However, complexes 14-17 provided activities up to 50000 mol C(2)H(4)/(mol Ni).h (16 and 17) in the presence of only 6 equiv of AlEtCl(2). The observed selectivities for ethylene dimers were higher than 91% (for 14 or 15 in the presence of only 1.3 equiv of AlEtCl(2)). The activities for 14-17 were superior to that of [NiCl(2)(PCy(3))(2)], a typical dimerization catalyst taken as a reference. The selectivities of the complexes 14-17 for ethylene dimers and alpha-olefins were the same order of magnitude. From the study of the phosphinite 9/AlEtCl(2) system, we concluded that in our case ligand transfer from the nickel atom to the aluminum cocatalyst is unlikely to represent an activation mechanism.     

Reactions of phosphine oxides with bromophosphoranimines; synthesis and unusual rearrangements of O-donor stabilized phosphoranimine cations

Reaction of phosphine oxides R(3)P═O [R = Me (1a), Et (1c), (i)Pr (1d) and Ph (1e)], with the bromophosphoranimines BrPR'R'P═NSiMe(3) [R' = R' = Me (2a); R' = Me, R' = Ph (2b); R' = R' = OCH(2)CF(3) (2c)] in the presence or absence of AgOTf (OTf = CF(3)SO(3)) resulted in a rearrangement reaction to give the salts [R(3)P═N═PR'R'O-SiMe(3)]X (X = Br or OTf) ([4]X). Reaction of phosphine oxide 1a with the phosphoranimine BrPMe(2)═NSiPh(3) (5) with a sterically encumbered silyl group also resulted in the analogous rearranged product [Me(3)P═N═PMe(2)O-SiPh(3)]X ([8]X) but at a significantly slower rate. In contrast, the direct reaction of the bulky tert-butyl substituted phosphine oxide, (t)Bu(3)P═O (1b) with 2a or 2c in the presence of AgOTf yielded the phosphine oxide-stabilized phosphoranimine cations [(t)Bu(3)P═O·PR'(2)═NSiMe(3)](+) ([3](+), R' = Me (d), OCH(2)CF(3) (e)). A mechanism is proposed for the unexpected formation of [4](+) in which the formation of the donor-stabilized adduct [3](+) occurs as the first step.     

A systematic study on the synthesis, reactivity and structure of ortho-palladated aryloximes, including the first cyclopalladated aryloximato and iminoaryloxime complexes

Complexes [Pd{C,N-Ar{C(Me)=NOH}-2}(μ-Cl)](2) (1) with Ar = C(6)H(4), C(6)H(3)NO(2)-5 or C(6)H(OMe)(3)-4,5,6, were obtained from the appropriate oxime, Li(2)[PdCl(4)] and NaOAc. They reacted with neutral monodentate C-, P- or N-donor ligands (L), with [PPN]Cl ([PPN] = Ph(3)P=N=PPh(3)), with Tl(acac) (acacH = acetylacetone), or with neutral bidentate ligands N^N (tetramethylethylenediamine (tmeda), 4,4'-di-tert-butyl-2,2'-bipyridine ((t)Bubpy)) in the presence of AgOTf or AgClO(4) to afford complexes of the types [Pd{C,N-Ar{C(Me)=NOH}-2}Cl(L)] (2), [PPN][Pd{C,N-Ar{C(Me)=NOH}-2}Cl(2)] (3), [Pd{C,N-Ar{C(Me)=NOH}-2}(acac)] (4) or [Pd{C,N-Ar{C(Me)=NOH}-2}(N^N)]X (X = OTf, ClO(4)) (5), respectively. Complexes 1 reacted with bidentate N^N ligands in the presence of a base to afford mononuclear zwitterionic oximato complexes [Pd{C,N-Ar{C(Me)=NO}-2}(N^N)] (6). Dehydrochlorination of complexes 2 by a base yielded dimeric oximato complexes of the type [Pd{μ-C,N,O-Ar{C(Me)[double bond, length as m-dash]NO}-2}L](2) (7). The insertion of XyNC into the Pd-C(aryl) bond of complex 2 produced the mononuclear iminoaryloxime derivative [Pd{C,N-C(=NXy)Ar{C(Me)=NOH}-2}Cl(CNXy)] (8) which, in turn, reacted with [AuCl(SMe(2))] to give [Pd{μ-N,C,N-C(=NXy)Ar{C(Me)=NOH}-2}Cl](2) (9) with loss of XyNC. Some of these complexes are, for any metal, the first containing cyclometalated aryloximato (6, 7) or iminoaryloxime (8, 9) ligands. Various crystal structures of complexes of the types 2, 3, 6, 7, 8 and 9 have been determined.     

Various forms of linear dipyridyls in discrete rectangles, dinuclear rods, and one-dimensional networks containing (eta5-pentamethylcyclopentadienyl)rhodium(III)

[Cp*Rh(eta1-NO3)(eta2-NO3)] (1) reacted with pyrazine (pyz) to give a dinuclear complex [Cp*Rh(eta1-NO3)(mu-pyz)(0.5)]2.CH2Cl2(3.CH2Cl2). Tetranuclear rectangles of the type [Cp*Rh(eta1,mu-X)(mu-L)(0.5)]4(OTf)4(4a: X = N3, L = bpy; 4b: X = N3, L = bpe; 4c: X = NCO, L = bpy) were prepared from [Cp*Rh(H2O)3](OTf)2 (2), a pseudo-halide (Me3SiN3 or Me3SiNCO), and a linear dipyridyl [4,4'-bipyridine (bpy) or trans-1,2-bis(4-pyridyl)ethylene (bpe)] by self-assembly through one-pot synthesis at room temperature. Treating complex with NH4SCN and dipyridyl led to the formation of dinuclear rods, [Cp*Rh(eta1-SCN)3]2(LH2) (5a: L = bpy; 5b: L = bpe), in which two Cp*Rh(eta1-SCN)3 units are connected by the diprotonated dipyridyl (LH2(2+)) through N(+)-H...N hydrogen bonds. Reactions of complex 2 with 1-(trimethylsilyl)imidazole (TMSIm) and dipyridyl (bpy or bpe) also produced another family of dinuclear rods [Cp*Rh(ImH)3]2.L (6a: L = bpy; 6b: L = bpe). Treating 1 and 2 with TMSIm and NH4SCN (in the absence of dipyridyl) generated a 1-D chain [Cp*Rh(ImH)3](NO3)2 (7) and a 1-D helix [Cp*Rh(eta1-SCN)2(eta1-SHCN)].H2O (8.H2O), respectively. The structures of complexes 3.CH2Cl2, 4a.H2O, 4c.2H2O, 5b, 6a, 7 and 8.H2O were determined by X-ray diffraction.     

Phosphino imidazoles and imidazolium salts for Suzuki C-C coupling reactions

The consecutive syntheses of imidazoles 1-(4-X-C(6)H(4))-4,5-R(2)-(c)C(3)HN(2) (3a, X = Br, R = H; 3b, X = I, R = Me; 3c, X = H, R = Me; 5, X = Fc, R = H; 7, X = C≡CFc, R = H; 9, X = C(6)H(5), R = Me; Fc = Fe(η(5)-C(5)H(4))(η(5)-C(5)H(5))), phosphino imidazoles 1-(4-X-C(6)H(4))-2-PR'(2)-4,5-R(2)-(c)C(3)N(2) (11a-k; X = Br, I, Fc, FcC≡C, Ph; R = H, Me; R' = Ph, (c)C(6)H(11), (c)C(4)H(3)O), imidazolium salts [1-(4-X-C(6)H(4))-3-R'-4,5-R(2)-(c)C(3)HN(2)]I (16a; X = Br, R = H, R' = n-Bu; 16b, X = Br, R = H, R' = n-C(8)H(17); 16c, X = I, R = Me, R' = n-C(8)H(17), 16d, X = H, R = Me, R' = n-C(8)H(17)) and phosphino imidazolium salts [1-C(6)H(5)-2-PR'(2)-3-n-C(8)H(17)-4,5-Me(2)-(c)C(3)N(2)]PF(6) (17a, R' = C(6)H(5); 17b, R' = (c)C(6)H(11)) or [1-(4-P(C(6)H(5))(2)-C(6)H(4))-3-n-C(8)H(17)-4,5-Me(2)-(c)C(3)HN(2)]PF(6), (20) and their selenium derivatives 1-(4-X-C(6)H(4))-2-P([double bond, length as m-dash]Se)R'(2)-4,5-R(2)-(c)C(3)N(2) (11a-Se-f-Se; X = Br, I; R = H, Me; R' = C(6)H(5), (c)C(6)H(11), (c)C(4)H(3)O) are reported. The structures of 11a-Se and [(1-(4-Br-C(6)H(4))-(c)C(3)H(2)N(2)-3-n-Bu)(2)PdI(2)] (19) in the solid state were determined. Cyclovoltammetric measurements were performed with the ferrocenyl-containing molecules 5 and 7 showing reversible redox events at E(0) = 0.108 V (ΔE(p) = 0.114 V) (5) and E(0) = 0.183 V (ΔE(p) = 0.102 V) (7) indicating that 7 is more difficult to oxidise. Imidazole oxidation does not occur up to 1.3 V in dichloromethane using [(n-Bu)(4)N][B(C(6)F(5))(4)] as supporting electrolyte, whereas an irreversible reduction is observed between -1.2 - -1.5 V. The phosphino imidazoles 11a-k and the imidazolium salts 17a,b and 20, respectively, were applied in the Suzuki C-C cross-coupling of 2-bromo toluene with phenylboronic acid applying [Pd(OAc)(2)] as palladium source. Depending on the electronic character of 11a-k, 17a,b and 20 the catalytic performance of the in situ generated catalytic active species can be predicted. As assumed, more electron-rich phosphines with their higher donor capability show higher activity and productivity. Additionally, 11e was applied in the coupling of 4-chloro toluene with phenylboronic acid showing an excellent catalytic performance when compared to catalysts used by Fu, Beller and Buchwald. Furthermore, 11e is eligible for the synthesis of sterically hindered biaryls under mild reaction conditions. C-C Coupling reactions with the phosphino imidazolium salts 17b and 20 in ionic liquids [BMIM][PF(6)] and [BDMIM][BF(4)] were performed, showing less activity than in common organic solvents.     

Synthesis,structure, and reactivity of some N-phosphorylphosphoranimines

A large series of new N-phosphorylphosphoranimines that bear potentially reactive functional groups on both phosphorus centers were prepared by silicon-nitrogen bond cleavage reactions of N-silylphosphoranimines. Thus, treatment of the N-silylphosphoranimines, Me(3)SiN=P(Me)(R)X (R = Me, Ph; X = OCH(2)CF(3) and R = Me, X = OPh), with phosphoryl chlorides, RP(=O)Cl(2) (R' = Cl, Me, Ph), readily afforded the corresponding N-phosphoryl derivatives, R'P(=O)(Cl)-N=P(Me)(R)X, in high yields. Subsequent reaction with 1 or 2 equiv of the silylamine, Me(3)SiNMe(2), resulted in ligand exchange at the phosphoryl (P=O) group to give the P-dimethylamino analogues, R'P(=O)(NMe(2))N=P(Me)(R)X (R' = Cl, NMe(2), Me, Ph; R = Me, Ph; X = OCH(2)CF(3), OPh). These new N-phosphorylphosphoranimines (and one thiophosphoryl analogue) were obtained as thermally stable, distillable liquids and were characterized by NMR ((1)H, (13)C, and (31)P) spectroscopy and elemental analysis. One member of the series, Cl(2)P(=O)N=P(Me)(Ph)OCH(2)CF(3) (4), was also studied by single-crystal X-ray diffraction which revealed that the formal P(O)-N single bond [1.55(1) A] is shorter than the formal N=PR(2)X double bond [1.60(1) A]. Such structural features are compared to those of similar compounds and discussed in relationship to the unexpected thermolysis pathways observed for these N-phosphorylphosphoranimines, none of which produced poly(phosphazenes).     

Nickel and iron complexes with oxazoline- or pyridine-phosphonite ligands; synthesis, structure and application for the catalytic oligomerisation of ethylene

The bis(oxazolinyl)phenylphosphonite ligand (bis(4,4-dimethyl-2-(1-hydroxy-1-methylethyl)-4,5-dihydrooxazole)phenylphosphonite, NOPONMe2)) and the new pyridine-phosphonite ligand (2-ethyl(1'-methyl-1-hydroxy)pyridine-6H-dibenz[c,e][1,2]oxaphosphorin) have been used for the preparation of the mononuclear complexes [NiCl2(NOPONMe2)] 18 and [NiCl2(6)2] 19, respectively, which catalyze the oligomerisation of ethylene with activities up to 57300 mol C2H4 mol Ni(-1) h(-1) (19 in the presence of only 6 equivalents of AlEtCl2). The selectivities for C4 dimers were as high as 90% (18 in the presence of only 2 equivalents of AlEtCl2) with selectivities for 1-butene of 21-22% of the C4 fraction. In the presence of 400 or 800 equivalents of MAO as cocatalyst, complex 19 yielded turnover frequencies of 7400 mol C2H4 mol Ni(-1) h(-1) and 13200 mol C2H4 mol Ni(-1) h(-1), respectively. The selectivities for 1-butene and ethylene dimers were similar to those obtained with AlEtCl2. The fact that 19 with a cyclic phosphonite moiety leads to higher activities and selectivities than 18 which contains an acyclic phosphonite group underlines the importance of the ligand on the catalytic properties of its metal complex. An unprecedented dinuclear iron complex [FeCl2(4,4-dimethyl-2-[(1-hydroxy-1-methyl)ethyl]-4,5-dihydrooxazolate)]2 20 was also obtained which contains two pentacoordinated metal centers coordinated by a bridging-chelating oxazoline-alcoholate. Complexes 18-20 are paramagnetic in solution, as determined by the Evans method.     

Lanthanide and uranium complexes with an SPS-based pincer ligand

Reactions of Ln(BH4)3(THF)n and [Li(Et2O)]SPS(Me)], the lithium salt of an anionic SPS pincer ligand composed of a central hypervalent lambda4-phosphinine ring bearing two ortho-positioned diphenylphosphine sulfide sidearms, led to the monosubstituted compounds [Ln(BH4)2(SPS(Me))(THF)2] [Ln = Ce (1), Nd (2)], while the homoleptic complexes [Ln(SPS(Me))3] [Ln = Ce (3), Nd (4)] were obtained by treatment of LnX3 (X = I, BH4) with [K(Et2O)][SPS(Me)]. The [UX2(SPS(Me))2] complexes [X = Cl (5), BH4 (6)] were isolated from reactions of UX4 and the lithium or potassium salt of the [SPS(Me)]- anion. The X-ray crystal structures of 1.1.5THF, 2.1.5THF, 3.2THF.2Et2O, and 5.4py reveal that the flexible tridentate [SPS(Me)]- anion is bound to the metal as a tertiary phosphine with electronic delocalization within the unsaturated parts of the ligand.     

新型手性膦噁唑啉铱络合物的合成及其在氢化反应中的应用

在鹰爪碱诱导下,2-氯甲基-4,4-二甲基噁唑啉与叔丁基苯基膦硼烷经络合反应,以43%的收率合成了光学纯度大于99%,手性中心在P上的新型手性噁唑啉氮膦配体(3); 3和铱配合物(［Ir(cod)Cl］₂)经络合反应以55%的收率制得两个新型手性膦噁唑啉铱络合物催化剂(1和2),其结构经¹H NMR, ¹³C NMR, ³¹P NMR和元素分析表征。考察了1和2对烯烃的不对称氢化反应的催化性能。结果表明：1具有较好的催化能力,收率＞92%,但催化剂的手性诱导能力较差(ee≤36%)。     

Synthesis, structures, and stability of N-donor-stabilized N-silylphosphoranimine cations

A series of DMAP-stabilized (DMAP=4-dimethylaminopyridine) N-silylphosphoranimine cations [DMAPPR(2)==NSiMe(3)](+), bearing R=Cl ([8](+)), Me ([10 a](+)), Me/Ph ([10 b](+)), Ph ([10 c](+)), and OCH(2)CF(3) ([10 d](+)) substituents, have been synthesized from the reactions of the parent phosphoranimines Cl(3)P==NSiMe(3) (3) and XR(2)P==NSiMe(3) (X=Cl (9), Br (11); R=Me (9 a and 11 a), Me/Ph (9 b and 11 b), Ph (9 c and 11 c), and OCH(2)CF(3) (9 d and 11 d)) with DMAP and silver salts as halide abstractors. Reactions in the absence of silver salts yield the corresponding cations, with halide counterions. The stability of the salts is highly dependent on the phosphoranimine substituent and the nature of the counteranion, such that electron-withdrawing substituents and non-coordinating anions yield the most stable salts. X-ray structural determination of the cations reveal extremely short phosphoranimine P--N bond lengths for the cations [8](+) and [10 d](+) (1.47-1.49 A) in which electron-withdrawing substituents are present and a longer phosphoranimine P--N length for the cation [10 a](+) (1.53 A) in which electron-donating substituents are present. Very wide bond angles at nitrogen are observed for the salts containing the cation [10 d](+) (158-166 degrees ) and indicate significant sp hybridization at the nitrogen centre.     

Amidoximes provide facile platinum(II)-mediated oxime-nitrile coupling

The nucleophilic addition of amidoximes R'C(NH(2))═NOH [R' = Me (2.Me), Ph (2.Ph)] to coordinated nitriles in the platinum(II) complexes trans-[PtCl(2)(RCN)(2)] [R = Et (1t.Et), Ph (1t.Ph), NMe(2) (1t.NMe(2))] and cis-[PtCl(2)(RCN)(2)] [R = Et (1c.Et), Ph (1c.Ph), NMe(2) (1c.NMe(2))] proceeds in a 1:1 molar ratio and leads to the monoaddition products trans-[PtCl(RCN){HN═C(R)ONC(R')NH(2)}]Cl [R = NMe(2); R' = Me ([3a]Cl), Ph ([3b]Cl)], cis-[PtCl(2){HN═C(R)ONC(R')NH(2)}] [R = NMe(2); R' = Me (4a), Ph (4b)], and trans/cis-[PtCl(2)(RCN){HN═C(R)ONC(R')NH(2)}] [R = Et; R' = Me (5a, 6a), Ph (5b, 6b); R = Ph; R' = Me (5c, 6c), Ph (5d, 6d), correspondingly]. If the nucleophilic addition proceeds in a 2:1 molar ratio, the reaction gives the bisaddition species trans/cis-[Pt{HN═C(R)ONC(R')NH(2)}(2)]Cl(2) [R = NMe(2); R' = Me ([7a]Cl(2), [8a]Cl(2)), Ph ([7b]Cl(2), [8b]Cl(2))] and trans/cis-[PtCl(2){HN═C(R)ONC(R')NH(2)}(2)] [R = Et; R' = Me (10a), Ph (9b, 10b); R = Ph; R' = Me (9c, 10c), Ph (9d, 10d), respectively]. The reaction of 1 equiv of the corresponding amidoxime and each of [3a]Cl, [3b]Cl, 5b-5d, and 6a-6d leads to [7a]Cl(2), [7b]Cl(2), 9b-9d, and 10a-10d. Open-chain bisaddition species 9b-9d and 10a-10d were transformed to corresponding chelated bisaddition complexes [7d](2+)-[7f](2+) and [8c](2+)-[8f](2+) by the addition of 2 equiv AgNO(3). All of the complexes synthesized bear nitrogen-bound O-iminoacylated amidoxime groups. The obtained complexes were characterized by elemental analyses, high-resolution ESI-MS, IR, and (1)H NMR techniques, while 4a, 4b, 5b, 6d, [7b](Cl)(2), [7d](SO(3)CF(3))(2), [8b](Cl)(2), [8f](NO(3))(2), 9b, and 10b were also characterized by single-crystal X-ray diffraction.     

Acrylonitrile insertion reactions of cationic palladium alkyl complexes

The reactions of acrylonitrile (AN) with "L(2)PdMe+" species were investigated; (L(2) = CH(2)(N-Me-imidazol-2-yl)(2) (a, bim), (p-tolyl)(3)CCH(N-Me-imidazol-2-yl)(2) (b, Tbim), CH(2)(5-Me-2-pyridyl)(2) (c, CH(2)py'(2)), 4,4'-Me(2)-2,2'-bipyridine (d), 4,4'-(t)Bu(2)-2,2'-bipyridine (e), (2,6-(i)Pr(2)-C(6)H(3))N=CMeCMe=N(2,6-(i)Pr(2)-C(6)H(3)) (f)). [L(2)PdMe(NMe(2)Ph)][B(C(6)F(5))(4)] (2a-c) and [{L(2)PdMe}(2)(mu-Cl)][B(C(6)F(5))(4)] (2d-f) react with AN to form N-bound adducts L(2)Pd(Me)(NCCH=CH(2))(+) (3a-f). 3a-e undergo 2,1 insertion to yield L(2)Pd{CH(CN)Et}+, which form aggregates [L(2)Pd{CH(CN)Et}](n)(n)(+) (n = 1-3, 4a-e) in which the Pd units are proposed to be linked by PdCHEtCN- - -Pd bridges. 3f does not insert AN at 23 degrees C. 4a-e were characterized by NMR, ESI-MS, IR and derivatization to L(2)Pd{CH(CN)Et}(PR(3))+ (R = Ph (5a-e), Me (6a-c)). 4a,b react with CO to form L(2)Pd{CH(CN)Et}(CO)+ (7a,b). 7a reacts with CO by slow reversible insertion to yield (bim)Pd{C(=O)CH(CN)Et}(CO)+ (8a). 4a-e do not react with ethylene. (Tbim)PdMe+ coordinates AN more weakly than ethylene, and AN insertion of 3b is slower than ethylene insertion of (Tbim)Pd(Me)(CH(2)=CH(2))(+) (10b). These results show that most important obstacles to insertion polymerization or copolymerization of AN using L(2)PdR+ catalysts are the tendency of L(2)Pd{CH(CN)CH(2)R}+ species to aggregate, which competes with monomer coordination, and the low insertion reactivity of L(2)Pd{CH(CN)CH(2)R}(substrate)+ species.     

Synthesis and structural characterization of new phosphinooxazoline complexes of iron

The first phosphinooxazoline chelate complexes of iron were synthesized, and their structural and electronic properties were studied.The known phosphinooxazolines 2-(2-(diphenylphosphino)phenyl)-4,5-dihydrooxazole (7a), 2-(2-(diphenylphosphino)phenyl)-4,4-dimethyl-4,5-dihydrooxazole (7b), (S)-4-benzyl-2-(2-(diphenylphosphino)phenyl)-4,5-dihydrooxazole (7e) and (R)-2-(2-(diphenylphosphino)phenyl)-4-phenyl-4,5-dihydrooxazole (7f) were synthesized by a modified three step literature procedure with improved 67-60% overall yields. The new electronically tuned phosphinooxazolines 2-(5-bromo-2-(diphenylphosphino)phenyl)-4,4-dimethyl-4,5-dihydrooxazole (7c), 3-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)-4-(diphenylphosphino)-N,N-dimethylaniline (7d) and 2-(2-(diphenylphosphino)-3-(trifluoromethyl)phenyl)-4,4-dimethyl-4,5-dihydrooxazole (7g) were synthesized in three to six steps with 59-29% overall yields. Reaction of 7a-f with CpFe(CO)₂I (110 °C, 2 h, toluene) gave the iodide salts of the new iron phosphinooxazoline complexes [CpFe(CO)(7a-f)]⁺ in 87-21% yield. The new complexes were characterized by X-ray and the molecular structures confirm the octahedral coordination geometry and the half-sandwich structure about the iron center. The impact of different oxazoline ligands on the steric and electronic properties of their iron complexes was determined by analysis of selected bond lengths, ν_CO stretching frequency and the oxidation potentials of the ligands and the iron complexes.