Zirconium and hafnium compounds containing various chelate ligands in the molecule

Conclusions A simple general method was proposed for the synthesis of chelate compounds of zirconium and hafnium of the R₄M, R₃MCl, and R₂MCl₂ types by the reaction of-diketones with either the chlorides or the chelate derivatives of the chlorides of Zr and Hf in the presence of an amine. Here members of the previously unknown coordination compounds of zirconium and hafnium were obtained, containing various-diketonic ligands in the molecule.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 689–691, March, 1973.     

Ruthenium carbene complexes containing bidentate and tridentate PO ligands

Treatment of [Ru(CHR)Cl₂(PCy₃)₂] (Cy = cyclohexyl) with Tl[N(Pr₂ⁱPO)₂] and AgL_OEt (L_OEt⁻ = [CpCo{P(O)(OEt)₂}₃]⁻) afforded the Ru carbene complexes [Ru(CHPh)(PCy₃)Cl{N(Pr₂ⁱPO)₂}] (1) and [L_OEtRu(CHR)(PCy₃)Cl] (2), respectively. Chloride abstraction of complex 2 with TlPF₆ in MeCN afforded [L_OEtRu(CHPh)(PCy₃)(MeCN)][PF₆] (3). Complexes 1 and 2 are capable of catalyzing ring-closing metathesis of diethyl 1,2-diallylmalonate. The crystal structure of complex 2 has been determined.     

Half-sandwich cyclopentandienyl molybdenum and tungsten nitrosyl complexes containing bidentate sulfur ligands

Half-sandwich nitrosyl complexes Cp*M(NO)I2 (M = Mo, or W) react with dithiocarbamates (NaS2CNMe2 and NaS2CNEt2) in THF to form of complexes: Cp*Mo(NO)I (S2CNMe2) (1), Cp*Mo(NO)I(S2CNEt2) (2), Cp*W(NO)I(S2CNMe2) (3) and Cp*W(NO)I(S2CNEt2) (4) in high yields. Treatments of Cp*M(NO)I2 (M = Mo, W) or [CpMo(NO)I2]2 with phosphinodithioate (NaS2PMe2) and phosphorodithioate [(NH4)S2P(OMe)2] result in complexes: Cp*Mo(NO)I(S2PMe2) (5a), CpMo(NO)I (S2PMe2) (5b), Cp*Mo(NO)(S2PMe2)2 (6a), CpMo (NO) (S2PMe2)2 (6b) and Cp*Mo(NO)I[S2P(OMe)2] (7), Cp*W(NO)I(S2PMe2) (8), Cp*W(NO) I[S2P(OMe)]2 (9). Treatment of (5a) and (5b) with an excess of NaS2PMe2 gives (6a) and (6b). The complexes have been characterized by their elemental analyses, i.r., 1H, 13C-n.m.r. and by EI-MS spectrometry.     

Di and monocarbonyl complexes of rhodium(I) containing singly charged bidentate ligands

Summary A series of neutral square planar rhodium(I) dicarbonyls containing singly charged bidentate ligands (salicylaldoxime, -benzoinoxime, -furildioxime, -benzildioxime, dimethylglyoxime, cupferron) has been prepared from three sources: (i) tetracarbonyl--dichlorodirhodium(I), (ii) solutions of hydrated rhodium chloride in DMF held under reflux and (iii) a carbonylated solution of hydrated rhodium chloride in boiling absolute alcohol. These dicarbonyls react with triphenylphosphine,-arsine and -stibine to yield monocarbonyl derivatives. The monocarbonyls form 1 : 1 adducts with TCNE. All complexes have been characterized by elemental analysis, i.r. and uv-visible spectra.     

The formation of cobalt(II) halide complexes containing neutral bidentate ligands

Summary Preparation of cobalt(II) halide complexes with neutral bidentate ligands, including 2-pyridyl alkyl ketones, is reported. 2-Pyridyl alkyl ketones act as monodentate or bidentate ligands depending on the reaction solvent used. Tetrahedral complexes are isolated for all potential -donating neutral ligands.trans-Octahedral complexes are formed only if the neutral ligands are strong -donors and -acceptors. The stereochemistry of cobalt(II) halide complexes is discussed in relation to the nature of the neutral ligands.     

Aluminum complexes incorporating bidentate amido phosphine ligands

A series of aluminum complexes supported by o-phenylene-derived amido phosphine ligands, N-(2-diphenylphosphinophenyl)-2,6-dimethylanilide ([Me-NP]-) and N-(2-diphenylphosphinophenyl)-2,6-diisopropylanilide ([iPr-NP]-), have been prepared. The reactions of trialkylaluminum with H[Me-NP] and H[iPr-NP], respectively, in refluxing toluene produced the corresponding dialkyl complexes [Me-NP]AlR(2) and [iPr-NP]AlR(2) (R = Me, Et). Deprotonation of H[Me-NP] with n-BuLi in THF at -35 degrees C followed by addition of AlCl(3) in toluene at -35 degrees C afforded [Me-NP]AlCl(2), which was subsequently reacted with 2 equiv of trimethylsilylmethyllithium in toluene to give [Me-NP]Al(CH(2)SiMe(3))(2). The aluminum complexes were all characterized by (1)H, (13)C, (31)P, and (27)Al NMR spectroscopy. The solid-state structures of monomeric, four-coordinate [Me-NP]AlEt(2) and [iPr-NP]AlMe(2) and five-coordinate [Me-NP]AlCl(2)(THF) were determined by X-ray crystallography. The (1)H NMR studies of [Me-NP]AlEt(2), [Me-NP]Al(CH(2)SiMe(3))(2), and [iPr-NP]AlEt(2) indicate diastereotopic alpha-hydrogen atoms in these molecules. Heteronuclear COSY and NOE experiments suggest that the phosphorus donor in [Me-NP]Al(CH(2)SiMe(3))(2) and [iPr-NP]AlEt(2) is coupled to only one of the diastereotopic alpha-hydrogen atoms that is virtually antiperiplanar with respect to the phosphorus atom.     

Synthesis and characterisation of nonclassical ruthenium hydride complexes containing chelating bidentate and tridentate phosphine ligands

The synthesis and characterisation of nonclassical ruthenium hydride complexes containing bidentate PP and tridentate PCP and PNP pincer-type ligands are described. The mononuclear and dinuclear ruthenium complexes presented have been synthesised in moderate to high yields by the direct hydrogenation route (one-pot synthesis) or in a two-step procedure. In both cases [Ru(cod)(metallyl)(2)] served as a readily available precursor. The influences of the coordination geometry and the ligand framework on the structure, binding, and chemical properties of the M--H(2) fragments were studied by X-ray crystal structure analysis, spectroscopic methods, and reactivity towards N(2), D(2), and deuterated solvents.     

Oxidative addition of organic halides to zerovalent palladium complexes containing rigid bidentate nitrogen ligands

Zerovalent complexes of the type Pd(Ar-BIAN)(alkene), i.e. complexes containing the rigid bidentate nitrogen ligands bis(arylimino) acenaphthene (Ar = p-Tol, p-MeOC₆H₄, o-Tol,o,o′-Me₂C₆H₃, o,o′-ⁱPr₂C₆H₃) and an electron-poor alkene have been shown to react with a variety of (organic) halides RX, including methyl, benzyl, aryl, acyl and allylic halides, to give the corresponding square planar divalent Pd(R)X(Ar-BIAN) or [Pd(η³-allyl)(Ar-BIAN)]X complexes. The new complexes obtained have been fully characterized and their fluxional behaviour in solution studied by ¹H NMR spectroscopy. The rate of oxidative addition of iodomethane to Pd(p-Tol-BIAN)(alkene) complexes was found to decrease with increasing Pd-alkene bond strength, i.e. dimethyl fumarate fumaronitrile, but oxidative addition to the fumaronitrile complex was accelerated by irradiation with a mercury lamp. Oxidative addition of allylic ha     

Transition metal complexes of bidentate Schiff base ligands

New Schiff base ligands derived from vanillin (HL¹), 4-dimethylaminobenzaldehyde (HL²) and 3,5-di-t-butyl-4-hydroxybenzaldehyde (HL³) with N-(pyridyl)-3-methoxy-4-hydroxy-5-aminobenzylamine (2) and their copper(II), cobalt(II), nickel(II), oxovanadium(IV) and zinc(II) transition metal complexes have been synthesized and characterized by elemental analyses, electronic and i.r. spectra, molar conductance data and by 1H and ¹³C n.m.r. spectra. The results indicate that the ligands coordinate through azomethine nitrogen and phenolic oxygen to the metal ions. In like manner, it was found that the pyridine and amine nitrogen atoms are not coordinated to the metal ions. The ¹H and ¹³C n.m.r. spectral data confirmed the suggested structure for the Schiff base ligands, and the mass spectra results confirmed the proposed structure of the ligands. The antimicrobial activity properties of the ligands and their metal complexes have been studied.     

Zirconium, hafnium, and tantalum amide silyl complexes: their preparation and conversion to metallaheterocyclic complexes via gamma-hydrogen abstraction by silyl ligands

New transition metal silyl amide complexes (Me(2)N)(3)Ta[N(SiMe(3))(2)](SiPh(2)Bu(t)) (1) and (Me(2)N)M[N(SiMe(3))(2)](2)(SiPh(2)Bu(t)) (M = Zr, 2a, and Hf, 2b) were found to undergo gamma-H abstraction by the silyl ligands to give metallaheterocyclic complexes (3) and (M = Zr, 4a, and Hf, 4b), respectively. The conversion of 1 to 3 follows first-order kinetics with DeltaH() = 23.6(1.6) kcal/mol and DeltaS() = 3(5) eu between 288 and 313 K. The formation of 4a from (Me(2)N)Zr[N(SiMe(3))(2)](2)Cl (5a) and Li(THF)(2)SiPh(2)Bu(t) (6) involves the formation of the intermediate 2a, followed by gamma-H abstraction. Kinetic studies of these consecutive reactions, a second-order reaction to give 2a and then a first-order gamma-H abstraction to give 4a, were conducted by an analytical method and a numerical method. At 278 K, the rate constants k(1) and k(2) for the two consecutive reactions are 2.17(0.03) x 10(-)(3) M(-)(1) s(-)(1) and 5.80(0.15) x 10(-)(5) s(-)(1) by the analytical method. The current work is a rare kinetic study of the A + B --> C --> D (+ E) consecutive reactions. Kinetic studies of the formation of a metallaheterocyclic moiety have, to our knowledge, not been reported. In addition, gamma-H abstraction by a silyl ligand to give such a metallaheterocyclic moiety is new. Theoretical investigations of the gamma-H abstraction by silyl ligands have been conducted by density functional theory calculations at the Becke3LYP (B3LYP) level, and they revealed that the formation of the metallacyclic complexes through gamma-H abstraction is entropically driven. X-ray crystal structures of (Me(2)N)(3)Ta[N(SiMe(3))(2)](SiPh(2)Bu(t)) (1), (Me(2)N)Zr[N(SiMe(3))(2)](2)Cl (5a), and (M = Zr, 4a, and Hf, 4b) are also reported.     

Oxorhenium(V) complexes containing bidentate N,O-donor ligands of the pyridyl type

The reaction of equimolar quantities of trans-[ReOCl₃(PPh₃)₂] and 8-hydroxyquinoline (Hhqn) in benzene led to the isolation of the six-coordinate complex [ReOCl₂(hqn)(PPh₃)] (1). With 2-pyridine-ethanol (Hhep) the compound [ReOCl₂(hep)(PPh₃)] (2) was obtained. Both hqn and hep ligands act as monoanionic bidentate N,O-donor chelates. Although the two complexes are very similar, there are some significant differences in certain bond distances and angles in them. Both complexes contain the nearly linear trans O=Re–O axis, with this angle equal to 160.9(2)° and 167.8(1)° in 1 and 2, respectively.     

Rhodium(I) phosphine complexes containing bidentate unsaturated thio ligands: I. Synthesis and characterisation

The rhodium(I) complexes (Ph₃P)₂Rh(LL′), in which LL′ is an unsaturated chelate coordinating via L = S and L′ = N, O, P or S, have been prepared from RhCl(PPh₃)₃ by two routes.Direct substitution of one Ph₃P and Cl^? by the chelate anion gives (Ph₃P)₂Rh[Ph₂PC(S)S] (L = S, L′ = P). Oxidative addition of an NH bond followed by reductive elimination of HCl results in (Ph₃P)₂Rh[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S), (Ph₃P)₂Rh[PhNC(S)NMe₂] (L = S, L′ = N), (Ph₃P)₂Rh[Ph₂PC(S)NPh) (L = S, L′ = P) and (Ph₃P)₂Rh[Ph₂P(O)C(S)NPh] (L = S, L′ = O).Reaction of the complexes (Ph₃P)₂Rh(LL′) with CO gives (CO)(Ph₃P)Rh(LL′) with CO trans to the chelate donor atom with the lowest trans-influence. Pt(PPh₃)₄ reacts with Me₂NC(S)N(H)C(S)NMe₂ and HN(Ph)C(S)PPh₂, respectively, to give H(Ph₃P)Pt[Me₂NC(S)NC(S)NMe₂] (L = S, L′ = S) and H(Ph₃P)Pt[Ph₂PC(S)NPh] (L = S, L′ = P).The coordinating atoms and their configurations have been assigned by IR ³¹P NMR and ¹H NMR. Some trend in IR and ³¹P NMR paramaters are discussed.     

Cyclization/hydrosilylation of functionalized 1,6-diynes catalyzed by cationic platinum complexes containing bidentate nitrogen ligands

A 1:1 mixture of the platinum dimethyl diimine complex [PhN[double bond]C(Me)C(Me)[double bond]NPh]PtMe(2) (4a) and B(C(6)F(5))(3) catalyzed the cyclization/hydrosilylation of dimethyl dipropargylmalonate (1) and HSiEt(3) to form 1,1-dicarbomethoxy-3-methylene-4-(triethylsilylmethylene)cyclopentane (3) in 82% isolated yield with 26:1 Z:E selectivity. Platinum-catalyzed diyne cyclization/hydrosilylation tolerated a range of functional groups including esters, sulfones, acetals, silyl ethers, amides, and hindered ketones. Diynes that possessed propargylic substitution underwent facile cyclization/hydrosilylation to form silylated 1,2-dialkylidene cyclopentanes as mixtures of regioisomers. Diynes that possessed an electron-deficient internal alkyne underwent cyclization/hydrosilylation in moderate yield to form products resulting from silyl transfer to the less substituted alkyne. The silylated 1,2-dialkylidenecyclopentanes formed via diyne cyclization/hydrosilylation underwent a range of transformations including protodesilylation, Z/E isomerization, and [4 + 2] cycloaddition with dieneophiles.