Synthesis and Structure of η4-Enone Complexes of Ruthenium(0)

A variety of [Ru(CO)₂L(η⁴enone)] complexes (L = phosphines, phosphites, and arsines, enone = (E)-4-phenylbut-3-en-2-one) have been synthesized. ¹H-, ¹³C-, and ³¹P-NMR spectra are reported and the X-ray structures of two Ru complexes with L ? Ph₃P(7), Et₃P ( 10 ) and one Fe complex with L ? Ph₃P ( 14 ) are presented. All three compounds crystallize in the same monoclinic space group P2₁/n with a = 10.575(2) Å, b =9.213(2) Å, and c = 27.608(5) Å, β = 100.04(2)°, Z = 4 for 7 , a = 10.276(3) Å, b = 12.935(3) Å, and c = 14.854(2) Å, β = 96.96(2)°, Z = 4 for 10 , and a = 10.492(2) Å, b = 9.232(3) Å, and c = 27.129(3) Å, β = 98.67(2)°, Z = 4 for 14 . The structures of the Ru complexes are compared with the Fe analogues. In the case of M ? Ru and L ? (EtO)₃P, (MeO)₃P, and (i-PrO)₃P ( 9 , 11 , and 13 , respectively) stereoisomers could be detected by ³¹P-NMR at room temperature, wich arise from rotation at the coordinated metal centre.     

Syntheses and reactions of [η5-CH3C5H4Cr(CO)3]2

The complexes [η⁵-CH₃C₅H₄Cr(CO)₃]₂ have been prepared, and their reactions with trivalent phosphorus ligands L (L = Ph₃P, (MeO)₃P, (EtO)₃P) shown to give [η⁵-CH₃C₅H₄Cr(CO)₂L]₂ complexes.     

Synthesis and 1H-, 13C-, and 57Fe-NMR spectra of mono- and bis[tricarbonyl(η4-diene)iron], and (η3-allyl)tetracarbonyliron trifluoroborate complexes

A variety of mono- and bis[Fe(CO)₃(η⁴-diene)] complex with alky, CH₂OH, CHO, COCH₃, COOR, and CN substituents on the 1,3-diene system have been synthesized. Dienes with a (Z)-configuration terminal Me group show steric inhibition of metal complexation resulting in lower yields and formation of tetracarbonyl(η²-diene) and tricarbonyl(η⁴-heterodiene) complexes as additional products. Regioselective attack by C-nucleophiles at the carbonyl C-atoms of the functional group with or without concomitant 1,3 mogration of the Fe(CO)₃ group was used to synthesize polyenes and isoprenoid building blocks as mono- or dinucliar Fe(CO)₃ complexes. Wittig-Horner-type reactions of Fe(co)₃-complexed synthons result in sterospecific formation of (E)-configurated olefins. The ¹H-, ¹³C- and ⁵⁷Fe-NMR spectra of olefinic and allylic organoiron complexes are reported, H,H,C,H, and C,C coupling constants have been evaluated and are analyzed in terms of the geometry of the coordinated diene. The results are corroborated by the crystal structure of tricarbonyl[3–6-η-((E)-6-methyl-3,5-heptadiene-2-one)]iron( 34 ) which shows an unusual distortion of the (CH₃)₂C = group, The ⁵⁷Fe-NMR chemical shifts extend over the ranges of 0–600 ppm for [Fe(CO)₃(η⁴-diene)] complexes, 780–1710 ppm for [Fe(CO)₄(η³-allyl)] [BF₄] and [FeX(CO)₃(η⁴-allyl)] complexes, and 1270–1690 ppm for [Fe(CO)₃(η⁴-enone)] complexes, relative to Fe(CO)₅.     

Topospecific Reactions of a [5.5.5.5]Fenestradiene with [Fe2(CO)9]

N, N-Dimethylformamide dimethyl acetal transforms an allylic OH group, which is part of a tetracyclic hydrocarbon in a unique elimination reaction into a [5.5.5.5]fenestradiene ( 2b → 4 ). In topologically selective reactions of this diene 4 with [Fe₂(CO)₉,], the [Fe(CO)₄(η²-diene)] and the [Fe(CO)3(η⁴-diene)] complexes 8 and 9 , respectively, are formed by complexation on one side of the diene moiety, whereas complexation on the other side leads to a [Fe(CO)₂(Cp)] complex 10 .     

Darstellung und Eigenschaften neuer kationischer Dienyl-isonitril-dicarbonyl-Komplexe des Eisens und Rutheniums

Preparation and Properties of New Cationic Dienyl-isonitrile-dicarbonyl Complexes of Iron and Ruthenium The hydride abstraction from the η⁴-diene isonitrile metal dicarbonyls M(η⁴-dien)(CNR)(CO)₂ (M = Fe, Ru; dien = C₆H₈ cyclohexadiene-1.3; C₇H₁₀ cycloheptadiene-1.3; R = Me, Et) with [Ph₃C]BF₄ lead to the η⁵-dienyl isonitrile dicarbonyl metal cations [M(η⁵-dienyl)(CNR)(CO)₂]⁺ [dienyl = cyclohexa-2.4-dien-1-yl (C₆H₇), cyclohepta-2.4-dien-1-yl (C₇H₉)]. [Fe(η⁵? C₈H₉)(CNMe)(CO)₂]⁺ (C₈H₉ = bicyclo[5.1.0]octa-3.5-dien-2-yl) is formed by protonation of Fe(η⁴? C₈H₈)(CNMe)(CO)₂ (C₈H₈ = COT) under valency isomerization. The two cations [Fe(η⁵? C₇H₉)(CNMe)(CO)₂]⁺ and [Fe(η⁵? C₈H₉)(CNMe)(CO)₂]⁺ can be deprotonated with NEt₃ to the neutral cycloheptatriene respectively COT complexes Fe(η⁴? C₇H₈)(CNMe)(CO)₂ and Fe(η⁴? C₈H₈)(CNMe)(CO)₂. The temperature dependent ¹³C-NMR spectra of [Fe(η⁵? C₇H₉)(CNMe)(CO)₂]⁺ and [Ru(η⁵? C₆H₇)(CNMe)(CO)₂]⁺ show the fluctional behaviour of these cations in solution. At low temperatures one CO group occupies the apical position of a square pyramid whereas the isonitrile ligand, the other CO group and the dienyl part are in the basal positions. The ΔG values of the CP exchange points out a higher activation energy as in the corresponding η⁴-diene metal complexes.     

Solvent-controlled formation of η-butadienyl or η-allyl group 6 transition metal complexes in water or alcohols

Preparation of acyl chloride, ester, amide or thioester-substituted η³-butadienyl complexes of the type [MCl(CO)₂(η³-CH₂C(COXR)CCH₂)(L₂)] (M=Mo,W; XR=Cl, OR, NHR, SR; L₂=1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline) from 1,4-dichloro-2-butyne and Ph₄P[MCl(CO)₃(L₂)] in water resulted in improved yields (M=Mo) and recycling of reagents. Whilst analogous reactions in anhydrous methanol to yield either substituted η³-butadienyl (XR=OR) or η³-allyl [MoCl(CO)₂(η³-CH₂C(CO₂R)C(OR)Me)(phen)] were dependent upon the presence of organic bases or ethers, reactions in propanol or butanol gave the η³-butadienyl complexes only. Possible mechanisms are discussed. Halide extraction from ester or amide butadienyl complexes in hydroxylic solvents gave highly reactive cations of the type [Mo(CO)₂(η³-butadienyl)(phen)(solvent]⁺, and carboxylate products were obtained by displacement of metal-bound solvent by glucuronate or hydroxybutyrate ions.     

Chemistry of (Carbonyl)(nitrosyl)[bis(phosphorus donor)]rhenium Complexes

The chemistry of [Re(CO)(NO)L₂] fragments (L ? phosphorus donor) was explored. Starting from [Re(CO)₅Cl] the synthesis of [Re₂Cl₂(μ-Cl)₂(CO)₄(NO)₂] ( 1 ) was accomplished via the preparation of [Et₄N]₂[Re₂Cl₂(μ-Cl)₂(CO)₆] and nitrosylation of this compound with [NO][BF₄]. Complex 1 was converted to [RecL₂(CO)(NO)L₂] complexes 2 ( a L = (MeO)₃P; b L = (EtO)₃P; c L = (i-PrO)₃P; d L ? Me₃P; e L ? Et₃P; f L ? Cy₃P) by heating with L in MeCN. In the case of the reaction of L = (MeO)₃P, a trisubstitued compound mer-{ReCl₂(NO)[P(OMe)₃]₃} 3 was also obtained. Replacement of the Cl ligands in 2a–e with Me groups was achieved by reacting them with MeLi in Et₂O yielding cis, trans-[Re(CO)(NO)Me₂L₂]complexes 4a–e . Reaction of 2a–e with Li[BHEt₃] led to substitution of one Cl by an H ligand with formation of [ReCl(CO)H(NO)L₂] compounds 5a–;e , displaying trans-H,NO geometries. The hydride-transfer agent Na[AlH₂(OCH₂CH₂OCH₃)₂] transformed 2 into the cis-dihydride systems [Re(CO)H₂(NO)L₂] 6a–f . Reductive carbonylation of 2a–d in the presence of Na/Hg and CO gave pentacoordinate [Re(CO)₂(NO)L₂] complexes 7b–d , and under comparable conditions the Cl substituents of 2b–f were replaced by tolane using Mg or t-BuLi giving trigonal bipyramidal [Re(CO)(NO)L₂(PhC?CPh)] compounds 8b–f . Complexes 5c , 6a , and 8d were characterized by X-ray crystal-structure analysis.     

Arene ruthenium metallacycles containing chelating thioamide ligands

Cationic, chiral arene ruthenium complexes of the type [Ru(η⁶-cym)(PPh₃){κ²N,S-PhNC(S)R}]BPh₄ were prepared in high yields by refluxing a mixture containing [(η⁶-cym)RuCl₂]₂, Ph₃P, PhNHC(S)R, NaBPh₄ and Et₃N in MeOH. A series of seven complexes with different thioamide ligands was prepared and fully characterised by spectroscopic methods including NMR spectroscopy and electrospray mass spectrometry. The solid-state structures of two complexes were determined by single crystal X-ray diffraction.     

Metallkomplexe mit biologisch wichtigen Liganden. XCV. η5- Pentamethylcyclopentadienyl-Rhodium-, -Iridium-, (η6-Benzol)-Ruthenium- und Phosphan-Palladium-Komplexe von Prolinmethylester und Prolinamid

Metal Complexes of Biologically Important Ligands. XCV. η⁵-Pentamethylcyclopentadienyl Rhodium, Iridium, η⁶- Benzene Ruthenium, and Phosphine Palladium Complexes of Proline Methylester and Proline Amide Proline methylester (L¹) and proline amide (L²) give with the chloro bridged complexes [(η⁵ -C₅Me₅)MCl₂]₂ (M ? Rh, Ir), [(η⁶ -benzene)RuCl₂]₂ and [Et₃PPdCl₂]₂ N and N,O coordinated compounds: (η⁵ -C₅Me₅)M(Cl₂)L¹ ( 1, 2 M ? Rh, Ir), [(η⁵-C₅Me₅) Rh(Cl)(L²)]⁺Cl^? ( 5 ), [(η⁶- C₆Me₆) Ru(Cl)(L²)]⁺Cl^? ( 6 ), [(η⁶-p-cymene)Ru(Cl)(L²)]⁺Cl^? ( 7 ), [(eta;⁵-C₅Me₅)M(Cl)(L²-H⁺)] ( 9, 10 M ? Rh, Ir), (Et₃P)Pd(Cl)₂L¹ ( 3 ), and [(Et₃P)Pd(Cl)(L²)]⁺Cl^? ( 8 ). The NMR spectra indicate that for 5 and 6 only one diastereoisomer is formed. The complexes 1, 2, 3 and 5 were characterized by X-ray diffraction.     

Spectroscopic,structural, electrochemical,and cytotoxicity studies on dithiocarbamato-chelated ruthenium organometallics incorporating imine-phenol function

The heterogeneous phase reaction of [Ru(η²-RL)(PPh₃)₂(CO)Cl] (1) with the sodium salts of dimethyl dithiocarbamate (^MeDTC), diethyl dithiocarbamate (^EtDTC), and pyrrolidine dithiocarbamate (^PyrDTC) ligands led to the isolation of bright-yellow crystalline solids of type [Ru(η¹-RL)(PPh₃)₂(CO)(^R′DTC)] (2(R)(^R′DTC)) where η²-RL is C₆H₂O-2-CHNHC₆H₄R(p)-3-Me-5, η¹-RL is C₆H₂OH-2-CHNC₆H₄R(p)-3-Me-5, R is Me, OMe, Cl, and R^′ = Me, Et, Pyr. The binding of dithiocarbamate ligand is accompanied by the dissociation of Ru-O and Ru-Cl bonds along with concomitant prototropic shift from iminium–phenolato to imine–phenol motif. The reaction also involves a sterically controlled change in rotational conformation in going to the products. The X-ray crystal structure of [Ru(η¹-ClL)(PPh₃)₂(CO)(^EtDTC)] (2(Cl)(^EtDTC)) has been described here. An account of different spectral (UV–Vis, IR, NMR) and electrochemical data of the complexes are also asserted. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) analyses were performed to scrutinize the electronic structure and the absorption spectra of the complexes. One of the dithiocarbamato complexes has also been found to have in vitro antiproliferative properties against MDA-MB-231 breast cancer cell line which was determined by MTT assay. Cell death occurs mainly through apoptosis and flow cytometric analysis indicates that the complex induces cell cycle arrest in the sub G0/G1 phase.     

A modular design of metal catalysts for the transfer hydrogenation of aromatic ketones

The ability of transition metal catalysts to add or remove hydrogen from organic substrates by transfer hydrogenation is a valuable synthetic tool. Towards a series of novel metal complexes with a P―NH ligand, [Ph₂PNHCH₂―C₄H₃O] derived from furfurylamine were synthesized. Reaction of [Ph₂PNHCH₂―C₄H₃O] 1 with [Ru(η⁶‐p‐cymene)(μ‐Cl)Cl]₂, [Ru(η⁶‐benzene)(μ‐Cl)Cl]₂, [Rh(μ‐Cl)(cod)]₂ and [Ir(η⁵‐C₅Me₅)(μ‐Cl)Cl]₂ gave a range of new monodentate complexes [Ru(Ph₂PNHCH₂―C₄H₃O)(η⁶‐p‐cymene)Cl₂] 2 , [Ru(Ph₂PNHCH₂―C₄H₃O)(η⁶‐benzene)Cl₂] 3 , [Rh(Ph₂PNHCH₂‐C₄H₃O)(cod)Cl] 4 , and [Ir(Ph₂PNHCH₂‐C₄H₃0)(η⁵‐C₅Me₅)Cl₂] 5 , respectively. All new complexes were fully characterized by analytical and spectroscopic methods. ³¹P‐{¹H} NMR, distortionless enhancement by polarization transfer (DEPT) or ¹H‐¹³C heteronuclear correlation (HETCOR) experiments were used to confirm the spectral assignments. Following activation by KOH, compounds 1 , 2 , 3 , 4 catalyzed the transfer hydrogenation of acetophenone derivatives to 1‐phenylethanol derivatives in the presence of iso‐PrOH as the hydrogen source. Notably [Ru(Ph₂PNHCH₂‐C₄H₃O)(η⁶‐benzene)Cl₂] 3 acts as an excellent catalyst, giving the corresponding alcohols in 98–99% yield in 20 min at 82°C (time of flight ≤ 297 h^?1) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes. Copyright © 2012 John Wiley & Sons, Ltd.     

Organometallic ruthenium, rhodium and iridium complexes containing a P-bound thiophene-2-(N-diphenylphosphino)methylamine ligand: Synthesis, molecular structure and catalytic activity

Reaction of Ph₂PNHCH₂-C₄H₃S with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂, [Ru(η⁶-benzene)(μ-Cl)Cl]₂, [Rh(μ-Cl)(cod)]₂ and [Ir(η⁵-C₅Me₅)(μ-Cl)Cl]₂ yields complexes [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-p-cymene)Cl₂], 1, [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2, [Rh(Ph₂PNHCH₂-C₄H₃S)(cod)Cl], 3 and [Ir(Ph₂PNHCH₂-C₄H₃S)(η⁵-C₅Me₅)Cl₂], 4, respectively. All complexes were isolated from the reaction solution and fully characterized by analytical and spectroscopic methods. The structure of [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2 was also determined by single crystal X-ray diffraction. 1-4 are suitable precursors forming highly active catalyst in the transfer hydrogenation of a variety of simple ketones. Notably, the catalysts obtained by using the ruthenium complexes [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-p-cymene)Cl₂], 1 and [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2 are much more active in the transfer hydrogenation converting the carbonyls to the corresponding alcohols in 98-99% yields (TOF ≤ 200 h⁻¹) in comparison to analogous rhodium and iridium complexes.     

Synthesis,characterization and biocidal studies of ruthenium(II) carbonyl complexes containing tetradentate Schiff bases

Stable ruthenium(II) complexes of Schiff bases have been prepared by reacting [RuHCl(CO)(PPh₃)₂(B)] (B = PPh₃, pyridine or piperidine) with bis(o-vanillin)ethylenediimine (valen), bis(o-vanillin)propylene-diimine (valpn), bis(o-vanillin)tetramethylenediimine (valtn), bis(o-vanillin)o-phenylenediimine (valphn), bis(salicylaldehyde)tetramethylenediimine (saltn) and bis(salicylaldehyde)o-phenylenediimine (salphn). These complexes have been characterised by elemental analyses, i.r., electronic, ¹H- and ³¹P{¹H}-n.m.r. spectral studies. In all the above reactions, the Schiff bases replace two molecules of Ph₃P, a hydride and a halide ion from the starting complexes, indicating that the Ru–N bonds present in the complexes containing heterocyclic nitrogen bases are stronger than the Ru–P bond to Ph₃P. The new complexes of the general formula [Ru(CO)(B)(L)] (B = PPh₃, py or pip; L = tetradentate Schiff bases) have been assigned an octahedral structure. Some of the Schiff bases and the new complexes have been tested against the pathogenic fungus Fusarium sp.     

Synthesis,characterization and catalytic studies of ruthenium(II) Schiff base complexes

Complexes of the type [Ru(CO)(EPh₃)(B)(L)] (E = P or As; B = PPh₃, AsPh₃, py or pip; L = dianion of the Schiff bases derived from the condensation of salicyloyl hydrazide with acetone, ethyl methyl ketone and salicylaldehyde have been synthesised by the reaction of equimolar amounts of [RuHCl(CO)(EPh₃)₂(B)] and Schiff bases in benzene. The resulting complexes have been characterized by analytical and spectral (i.r., electronic, n.m.r.) data. The arrangements of Ph₃P groups around the Ru metal was determined from ³¹P-n.m.r. spectra. An octahedral structure has been assigned to all the new complexes. All the complexes exhibit catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in the presence of N-methylmorpholine-N-oxide as co-oxidant.     

Iron‐Complex‐Catalyzed C?C Bond Cleavage of Organonitriles: Catalytic Metathesis Reaction between H?Si and R?CN Bonds to Afford R?H and Si?CN Bonds

The first example of the catalytic C? CN bond cleavage of acetonitrile as well as Si? CN bond formation have been achieved in the photoreaction of MeCN with Et₃SiH promoted by [Cp(CO)₂FeMe]. This catalytic system is applicable to other organonitriles. Several iron complexes [(η⁵‐C₅R₅)(CO)₂FeR′] (R₅=H₅, H₄Me, Me₅, H₄SiMe₃, H₄I, H₄P(O)(OMe)₂; R′=SiMe₃, CH₂Ph, Me, Cl, I) were examined as catalyst, and [Cp(CO)₂FeMe] was found to be the best precursor. A catalytic reaction cycle was proposed, which involves oxidative addition of Et₃SiH to [Cp(CO)FeMe], reductive elimination of CH₄ from [Cp(CO)FeMe(H)(SiEt₃)], coordination of RCN to [Cp(CO)Fe(SiEt₃)], silyl migration from Fe to N in the coordinated RCN, and dissociation of Et₃SiNC from Fe. The reaction with MeCN of [Cp(CO)Fe(py)(SiEt₃)], which was newly prepared and determined by X‐ray analysis, and the reaction of Et₃SiH with MeCN in the presence of a catalytic amount of [Cp(CO)Fe(py)(SiEt₃)] showed that the 16‐electron species [Cp(CO)Fe(SiEt₃)] is the active species in the catalytic cycle (TON up to 251).     

Übergangsmetall-substituierte phosphane,arsane und stibane : XXIX. Metallierte arsane und stibane mit chiralem eisen-substituenten

The reaction of Cp(CO)₂FeEMe₂ (E  As, Sb, Bi) with Me₃P, Et₃P, Me₂PhP and (MeO)₃P leads to a CO/R₃P exchange and formation of the chiral derivatives Cp(CO)(R₃P)FeEMe₂. Cp(CO)[(MeO)₃P]FeEMe₂ rearranges already at room temperature to Cp(CO)[(Me₃E]FeP(O)(OMe)₂ which is transformed by (MeO)₃P to Cp(CO)[(MeO)₃P]FeP(O)(OMe)₂. The high nucleophilicity of the new organometallic Lewis bases is established by the easy conversion of Cp(CO)(Me₃P)FeSbMe₂ to [Cp(CO)(Me₃P)Fe(SbMe₃)]I with MeI, or to [Cp(CO)(Me₃P)FeSbMe₂Fe(CO)LCp]Hal (L  CO, Hal  Cl; L  Me₃P, Hal  Br) with Cp(CO)LFe-Hal, respectively. The new compounds are characterized by spectroscopy and elementary analyses.     

Rules governing asymmetric synthesis with organotransition metal complexes

A set of rules are presented which allow prediction of (1) the conformational properties of organotransition metal complexes of the type (η⁵-C₅H₅)M(Ph₃P)(L)R [M = Fe, Co, Re; L = CO, NO]; and (2) the stereochemical consequences of their reactions.     

Applications of transition metal complexes containing aminophosphine ligand to transfer hydrogenation of ketones

Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. Reaction of [Ph₂PNHCH₂‐C₄H₃S] with [Ru(η⁶‐benzene)(µ‐Cl)Cl]₂, [Rh(µ‐Cl)(cod)]₂ and [Ir(η⁵‐C₅Me₅)(µ‐Cl)Cl]₂ gave a range of new monodendate complexes [Ru(Ph₂PNHCH₂‐C₄H₃S)(η⁶‐benzene)Cl₂], 1, [Rh(Ph₂PNHCH₂‐C₄H₃S)(cod)Cl], 2, and [Ir(Ph₂PNHCH₂‐C₄H₃S)(η⁵‐C₅Me₅)Cl₂], 3, respectively. All new complexes were fully characterized by analytical and spectroscopic methods. ¹H? ³¹P NMR, ¹H? ¹³C HETCOR or ¹H? ¹H COSY correlation experiments were used to confirm the spectral assignments. 1–3 are suitable catalyst precursors for the transfer hydrogenation of acetophenone derivatives. Notably [Ru(Ph₂PNHCH₂‐C₄H₃S)(η⁶‐benzene)Cl₂], 1, acts as an excellent catalyst, giving the corresponding alcohols in 98–99% yields in 30 min at 82 °C (TOF ≤200 h^?1) for the transfer hydrogenation reaction in comparison to analogous rhodium or iridium complexes. This transfer hydrogenation is characterized by low reversibility under these conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

Nickel Tetracarbonyl as Starting Material for the Synthesis of NHC-stabilized Nickel(II) Allyl Complexes

A novel, useful in situ synthesis for NHC nickel allyl halide complexes [Ni(NHC)(η³-allyl)(X)] starting from [Ni(CO)₄], NHC and allyl halides is presented. The reaction of [Ni(CO)₄] with (i) one equivalent of the corresponding NHC and (ii) with an excess of the corresponding allyl chloride at room temperature leads with elimination of carbon monoxide to complexes of the type [Ni(NHC)(η³-allyl)(X)]. This approach was used to synthesize the complexes [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 2 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 3 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 4 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Br)] ( 5 ), [Ni(Me₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 6 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Cl)] ( 7 ). The complexes 1 to 7 were characterized using NMR and IR spectroscopy and elemental analysis, and the molecular structures are provided for 2 and 7 . The allyl nickel complexes 1 – 7 are stereochemically non-rigid in solution due to (i) NHC rotation about the nickel-carbon bond, (ii) allyl rotation about the Ni–η³-allyl axis and (iii) π–σ–π allyl isomerization processes. The allyl halide complexes can be methylated as was demonstrated by the methylation of a number of the complexes [Ni(NHC)(η³-allyl)(X)] with methylmagnesium chloride or methyllithium, which led to isolation of the complexes [Ni(Me₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 8 ), [Ni(tBu₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 9 ), [Ni(iPr₂Im^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 10 ), [Ni(iPr₂Im)(η³-H₂C -C (Me)-C H₂)(Me)] ( 11 ), [Ni(iPr₂Im)(η³-H₂C -C (H)-C (Me)₂)(Me)] ( 12 ), and [Ni(EtiPrIm^Me)(η³-H₂C -C (Me)-C H₂)(Me)] ( 13 ). These complexes were fully characterized including X-ray molecular structures for 10 and 11 .     

An easy and direct synthetic route to phosphamido niobocenes through nucleophilic attack of phosphide niobocene complexes on acyl halides

The synthesis of the new cationic functionalized phosphane niobocene complexes [Nb(η⁵-C₅H₄SiMe₃)₂(P(CH₂CO(C₆H₅))Ph₂)(L)]Cl, LCO (3) or CNXylyl (4), and new phosphamido-niobocene complexes [Nb(η⁵-C₅H₄SiMe₃)₂(P{CO(C₆H₅)}Ph₂)(L)]Cl, LCO (5), CNXylyl (6), [Nb(η⁵-C₅H₄SiMe₃)₂(P(COCH(C₆H₅)₂)Ph₂)(L)]Cl, LCO (7) or CNXylyl (8), has been achieved. The complexes were prepared by reaction of the Lewis base niobocene complexes [Nb(η⁵-C₅H₄SiMe₃)₂(PPh₂)(L)], LCO (1) or CNXylyl (2), with the appropriate RX (PhCOCH₂Cl, chloroacetophenone) and RCOX (PhCOCl, benzoyl chloride, Ph₂CHCOCl, diphenylacetyl chloride) reagents through the formation of new P–C bonds in the corresponding nucleophilic substitution reactions. These processes afforded new metallophosphanes in which one of the substituents on the phosphorus atom contains a ketonic moiety. The presence of the carbonyl group in the coordination sphere of phosphorus increases the coordination possibilities of the phosphane and enriches the applications of these complexes.