The Search for New‐Generation Olefin Polymerization Catalysts: Life beyond Metallocenes

Even late transition metal complexes function as active and selective catalysts for α‐olefin polymerization. The discovery of a highly active family of catalysts 1 based on iron, a metal that had no previous track record in this field, has highlighted the possibilities for further new catalyst discoveries. As a result, an intense search has developed for new‐generation catalysts, in both academic and industrial research laboratories. R¹=H, Me; R²=Me, iPr; R³=H, Me, iPr; R⁴=H, Me; X=halide.     

Electron density distributions in substituted 2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-dienes studied by NMR spectroscopy

The signals in the¹³C NMR spectra of 2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-dienes (R¹=R²=H, Me,cyclo-C₃H₅, SiMe₃, SnMe₃, R¹=Me, R²=H, Cl) were completely assigned using 2D NMR spectroscopy. The pattern of the variation of the chemical shifts in the¹³C NMR spectra indicates that the effects of substituents R¹ and R² on the heterocycle and on the phenyl groups are of inductive rather than mesomeric origin and include the direct through-space polarization of bonds (field effect). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1962–1965, November, 1997.     

Enantiomerically Pure Cyclic trans-1,2-Diols,Diamines, and Amino Alcohols by Intramolecular Pinacol Coupling of Planar Chiral Mono-Cr(CO)3 Complexes of Biaryls

Without any formation of stereoisomers , the intramolecular pinacol cyclization of 1 —planar chiral mono-Cr(CO)₃ complexes of 1,1′-biphenyls with carbonyl functionalities at the 2- and 2′-positions—with samarium diiodide gives cyclic trans-1,2-diols 2 . Upon exposure to sunlight, the chromium-complexed diols 2 produce optically pure chromium-free trans-diols 3 . Similarly, the corresponding enantiomerically pure trans-1,2-diamines and amino alcohols are obtained from the planar chiral chromium complexes of biphenyls with diimino or keto-imino functionalities. R¹=H, OMe; R²=H, Me; R³=H, Me.     

Synthesis in Water and Antimicrobial Activity of 5-Trichloromethyl-4,5-dihydroisoxazoles

Two series of 5-trichloromethylisoxazoles were synthesized from the cyclocondensation of 1,1,1-trichloro-4-methoxy-3-alken-2-ones [Cl₃CC(O)C(R²) = C(R¹)OMe, where R¹ = H, Me, Et, Pr, iso-Pr, cyclo-Pr, Bu, terc-Bu, CH₂Br, CHBr₂, CH(Me)SMe, (CH₂)₂Ph, and Ph, and R² = H; R¹ = H and R² = Me and Et; R¹ and R² = -(CH₂)₄- and -(CH₂)₅-; and R¹ = Et and Ph and R² = Me] with hydroxylamine hydrochloride through a rapid one-pot reaction in water. The 5-trichloromethyl-4,5-dihydroisoxazoles were aromatized by reaction with concentrated sulfuric acid to obtain the respective 5-trichloromethylisoxazoles. Their structures were confirmed by elemental analysis, ¹H/¹³C nuclear magnetic resonance, and electron impact mass spectroscopy. Crystal structure analysis for 5-triclhoromethyl-5-hydroxy-3-propyl-4,5-dihydroisoxazole (2d) and 5-trichloromethyl-5-hydroxy-3,4-hexamethylene-4,5-dihydroisoxazole (2o) is presented. The antimicrobial activities of the 5-trichloromethyl-4,5-dihydroisoxazole derivatives were examined using the standard twofold dilution method against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and yeasts (Candida spp. and Cryptococcus neoformans). All of the tested 5-trichloromethyldihydroisoxazoles exhibited antibacterial and antifungal activities at the tested concentrations.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Simplified Approach to the Regiospecific Synthesis of Trichloromethylpyrazolines Using Microwave Irradiation

Twelve novel 3-alkyl[aryl]-1-carboxamides-5-trichloromethyl-5-hydroxy-4,5-dihydro-lH-pyrazole have been synthesized in good yields (72–90%) using environmentally benign microwave-induced techniques. The compounds were synthesized from the cyclocondensation of 4-alkoxy-1,1,1-trichloro-3-alkyl[aryl]-2-ones [Cl₃CC(O)C(R²) = C(R¹)OR, where R = Me, Et; R¹ = H, Me, Et, Pr, i-Pr, i-Bu, t-Bu, Ph, Ph-4-NO₂, Ph-4-F, Ph-4-Cl, Ph-4-Br; and R² = H, Me] with semicarbazide hydrochloride in the presence of pyridine and using methanol/water (3:1 v/v) as the solvent. The advantages of using microwave irradiation, rather than a conventional method, were demonstrated.     

Novel Asymmetric and Stereospecific Aziridination of Alkenes with a Chiral Nitridomanganese Complex

The addition of pyridine N -oxide is necessary to obtain high enantioselectivities in the asymmetric aziridination of styrene derivatives through transfer of a nitrogen atom from chiral, toluenesulfonic anhydride activated nitridomanganese complex 1 [Eq. (a)]. Remarkably, high stereospecificity was observed in all the aziridinations of trans- and cis-1,2-disubstituted alkenes. R¹=H, Me, nPr, iPr; R²=H, Me; Ts=p-toluenesulfonyl.     

Separation of racemiccloso-3,3-(η3,2-norbornadienyl)rhodacarboranes into enantiomers by HPLC on chiral stationary phasesinto enantiomers by HPLC on chiral stationary phases

Racemiccloso-rhodacarboranes,vis. closo-(η^3,2-C₇H₃-2-CR ₂ ¹ )-1-R²-2-R³-3,1,2-RhC₂B₉H₉ (R¹=R²=R³=H; R¹=H, R²=R³=Me; R¹=R²=R³=Me) and (closo-2,2-(η^3,2-C₇H₇-2-CH₂)-2,1,7-RhC₂B₉H₁₁), were successfully separated into enantiomers by high-performance liquid chromatography (HPLC). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 759–761, April, 2000.     

Synthesis and Characterization of Ruthenium Complexes with Substituted Pyrazino[2,3‐f][1,10]‐phenanthroline (=Rppl; R=Me,COOH, COOMe)

A series of substituted pyrazino[2,3‐f][1,10]‐phenanthroline (Rppl) ligands (with R=Me, COOH, COOMe) were synthetized (see 1 – 4 in Scheme 1). The ligands can be visualized as formed by a bipyridine and a quinoxaline fragment (see A and B ). Homoleptic [Ru(R¹ppl)₃](PF₆)₂ and heteropleptic [Ru(R¹ppl){(R²)₂bpy}₂](PF₆)₂ (R¹=H, Me, COOMe and R²=H, Me) metal complexes 5 – 7 and 8 – 13 , respectively, based on these ligands were also synthesized and characterized by conventional techniques (Schemes 2 and 3, resp.). In the heteroleptic complexes, the R¹‐ppl ligand reduces at a less‐negative potential than the bpy ligand, reflecting the acceptor property conferred by the quinoxaline moiety. The potentiality of some of these complexes as solar‐cell dyes is discussed.     

Substantially enhancing the catalytic performance of bis(imino)pyridylcobaltous chloride pre‐catalysts adorned with benzhydryl and nitro groups for ethylene polymerization

Variations in the ligand structure of homogeneous late transition metal catalysts through judicious choice and location of substituent is the foremost strategy in improving their catalytic performance for ethylene polymerization. In this contribution, symmetrical and unsymmetrical bis(imino)pyridylcobaltous chloride complexes adorned with nitro and benzhydryl groups {2‐[1‐(2,6‐dibenzhydryl‐4‐nitrophenylimino)ethyl]‐6‐[1‐(alkylphenylimino)ethyl]pyridylcobaltous chloride (alkyl: R¹ = Me and R² = H, Co1 ; R¹ = Et and R² = H, Co2 ; R¹ = ⁱPr and R² = H, Co3 ; R¹ and R² = Me, Co4 ; R¹ = Et and R² = Me, Co5 ; R¹ = benzhydryl and R² = NO₂, Co6 )} have been prepared and applied as catalysts for ethylene polymerization. The molecular structure of Co1 and Co2 revealed the unequal steric protection of the cobalt center induced by bis(imino)pyridine chelate. In the presence of methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) activators at different ethylene feeding rates (1 and 10 atm), catalysts Co1 – Co5 displayed high activities at 10 atm ethylene and produced strictly linear polyethylene (PE) with high molecular weight, Co2 /MMAO being the most highly active catalytic system showing the highest activity of 9.41 × 10⁶ g of PE (mol of Co)^?1 h^?1 which is three times higher than that of prototypal cobalt catalyst ( Co0 ) under identical conditions. Moreover, high melt temperature and unimodal molecular weight distribution are the characteristics of the resulting polyethylene.     

Nucleophilic Addition to CC Bonds,Part X

A mechanistic model is presented for the base‐catalyzed intramolecular cyclization of polycyclic unsaturated alcohols of type A to ethers D (Scheme 1). The alkoxide anion B is formed first in a fast acid‐base equilibrium. For the subsequent reaction to D , a carbanion‐like transition state C is proposed. This mechanism is in full agreement with our results regarding the influence of substituents on the regioselectivity and the rate of cyclization. We studied the effect of alkyl substituents in allylic position (alkylated endocylic olefinic alcohols 1 – 3 ) and, especially, at the exocyclic double bond ( 12 – 15 ). The fastest cyclization (k_rel=1) is 12 → 16 , which proceeds via a primary carbanion‐like transition state ( E : R¹=R²=H). The corresponding processes 13 → 17 and 14 → 17 are characterized by a less‐stable secondary carbanion‐like transtition state ( E : R¹=Me, R²=H, or vice versa) and are slower by a factor of 10⁴. The slowest reaction (k_rel ca. 10⁻⁶) is the cyclization 15 → 18 via a tertiary carbanion‐like transition state ( E : R¹=R²=Me).     

Homogeneous and Solid-Gas Hydrogenation of Alkynes in the Presence of the Clusters Fe3(CO)9(ε-RC2 R 1) {R=R 1=Ph, Et; R=Me, R 1=Ph}: Characterization of New Metallacyclic Derivatives

The clusters Fe₃(CO)₉(RC₂ R ¹) (R=R ¹=Ph, Et; R=Me, R ¹=Ph), complexes 1a, 1b, 1c, containing an alkyne bound in perpendicular fashion with respect to a cluster edge, catalyze the hydrogenation of some acetylenes either under homogeneous and solid–gas conditions. We hypothesize that cluster catalysis occurs and that the catalytic activity is related to the coordinating ability of the alkynic substrates. Competition between hydrogenation and formation of metallacyclic byproducts occurs. The new metallacyclic derivatives Fe₃(CO)₆(-CO)₂{(RC₂ R ¹)(R ²C₂ R ³)}, Fe₂(CO)₆{(RC₂ R ¹)(R ²C₂ R ³)} {R=R ¹=Et, R ²=R ³=H, Ph; R ²=Me, R ³=Et, Ph; R ²=H, R ³=Bu ^t . R=R ¹=Ph, R ²=Me, R ³=Et, Ph} (complexes 2, 3) were found both in the homogeneous reaction mixtures and after the solid–gas reactions. The formation of these products lowers the catalytic activity.     

1,2-dihydro-1,2,4,3-triazaphospholo[4,5-a]quinolines as electron carriers in the electrochemical reduction of 1,1-dichloro-2-methoxycarbonyl-2-methylcyclopropane

Electrochemical reduction of 1-X-1-R¹-5-methyl-2-phenyl-7-R²-1,2-dihydro-1,2,4,3-tri-azaphospholo[4,5-a]quinolines1–5 (1: X is the lone electron pair (LEP), R¹=Et₂N, R²=Me;2: X=LEP, R¹=Ph, R²=H;3: X=S, R¹=Et₂N, R²=H;4: X=LEP, R¹=Et₂N, R²=H;5: X=LEP, R¹=MeO, R²=H) in DMF with 0.1M Bu₄NI as supporting electrolyte is reversible and results in metastable radical anions. Radical anions of compounds1–3 efficiently reduce 1,2-dichloro-2-methoxycarbonyl-2-methylcyclopropane both in the presence and in absence of Ni¹¹ ions. Effective reduction rate constants have been evaluated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 1999.     

Steering of Configuration by (2‐Phosphanyl)phenolato Ligands in Trimethylphosphane Iron Complexes

(Diphenylphosphanyl)phenols C₆H₃(1‐OH)(2‐PPh₂)(4‐R¹)(6‐R²), abbreviated as (P^∧OH), oxidatively add to Fe(PMe₃)₄ affording hydridoiron(II) compounds fac‐FeH(P^∧O)(PMe₃)₃ ( 1 : R¹=R²=H; 2 : R¹=Me, R²=H; 3 : R¹=OMe, R²=H; 4 : R¹=Me, R²=CMe₃; 5 : R¹=R²=CMe₃) with high stereoselectivity. (2‐diphenylphosphanyl)thiophenol (P^∧SH) reacts accordingly forming fac‐FeH(P^∧S)(PMe₃)₃ ( 9 ). Complete assignment of ¹H, ¹³C, and ³¹P signals is achieved by 2D heteronuclear shift correlations. 4,6‐Di‐tert‐butyl‐(2‐diphenylphosphanyl)phenol reacts with FeI(Me)(PMe₃)₄ to form FeI(P^∧O)(PMe₃)₂ ( 6 ). 4 , 5 and 9 under 1 bar of CO are converted to monocarbonyl derivatives FeH(P^∧X)(CO)(PMe₃)₂ ( 7 , 8 : X = O; 10 : X = S) which in solution form mixtures of two isomers A and B . 4 and 5 react with their parent phosphanylphenols, respectively, to give diamagnetic complexes Fe(P^∧O)₂(PMe₃) ( 11 , 12 ) which dissociate trimethylphosphane to give paramagnetic compounds Fe(P^∧O)₂. The same phosphanylphenols react with FeCl₃ to afford racemic mixtures of complexes Fe(P^∧O)₃ ( 13 , 14 ). Structural data were also obtained from single crystals of compounds 1 , 5 , and 11 .     

Unprecedented Reaction Pathway of Sterically Crowded Calcium Complexes: Sequential C−N Bond Cleavage Reactions Induced by C−H Bond Activations

Five bis(quinolylmethyl)‐(1H ‐indolylmethyl)amine (BQIA) compounds, that is, {(quinol‐8‐yl‐CH₂)₂NCH₂(3‐Br‐1H ‐indol‐2‐yl)} ( L¹H ) and {[(8‐R³‐quinol‐2‐yl)CH₂]₂NCH(R²)[3‐R¹‐1H ‐indol‐2‐yl]} ( L^2–5H ) ( L²H : R¹=Br, R²=H, R³=H; L³H : R¹=Br, R²=H, R³=i Pr; L⁴H : R¹=H, R²=CH₃, R³=i Pr; L⁵H : R¹=H, R²=n Bu, R³=i Pr) were synthesized and used to prepare calcium complexes. The reactions of L^1–5H with silylamido calcium precursors (Ca[N(SiMe₂R)₂]₂(THF)₂, R=Me or H) at room temperature gave heteroleptic products ( L^{1, 2} )CaN(SiMe₃)₂ ( 1 , 2 ), ( L^{3, 4} )CaN(SiHMe₂)₂ ( 3 a , 4 a ) and homoleptic complexes ( L^{3, 5} )₂Ca ( D3 , D5 ). NMR and X‐ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L^3–5 )CaN(SiMe₃)₂) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of (E )‐1,2‐bis(8‐isopropylquinol‐2‐yl)ethane.     

Novel Asymmetric Formylation of Aromatic Compounds: Enantioselective Synthesis of Formyl 7,8‐Dipropyltetrathia[7]helicenes

Asymmetric formylation of aromatic compounds is virtually unexplored. We report the synthesis and evaluation of a library including 20 new chiral formamides in the kinetic resolution of 7,8‐dipropyltetrathia[7]helicene, affording the corresponding formyl‐ or diformylhelicenes in up to 73 % ee, making enantiopure compounds available by recrystallisation. With the N,N‐disubstituted formamides used in this study, the best enantioselectivity has been achieved with R¹=iPr, R²=Me, R³=H, R⁴=1‐naphthyl or its 1‐pyrenyl equivalent.     

Enol ethers and acetals: acylation with dichloroacetyl,acetyl and benzoyl chloride in ionic liquid medium

Synthesis of 4-alkoxy-1,1-dichloro-3-alken-2-ones [CHCl₂C(O)C(R²)C(R¹)-OR, where R, R¹, R² = Et, H, H; Me, Me, H; Et, H, Me; Me, –(CH₂)₂–; Me, –(CH₂)₃–; Et, Et, H; Et, Bu, H; Et, i-Pr, H; Et, i-Bu, H; Me, Ph, H; Me, thien-2-yl, H] from acylation of enol ethers and acetals with dichloroacetyl chloride, in ionic liquid ([BMIM][BF₄] or [BMIM][PF₆]) is reported. The synthesis of alkenones [R³–C(O)C(R²)C(R¹)-OR], where R/R¹/R²/R³ = Et/H/H/Ph, t-Bu/H/H/Ph, Me/-(CH₂)₄/Ph, Me/-(CH₂)₄/Me] from the reaction of enol ethers with benzoyl chloride or acetyl chloride, in ionic liquid [BMIM][BF₄], is also reported. Last products are described for the first time.     

Isomerism of copper(II) coordination compounds with hydroxamic acids

The structure of Cu^II complexes with hydroxamic acids Cu[R¹N(O)−(O)CR²]₂, where R¹=Ph, R²=Me; R¹=Me, R²=Ph, was studied by ESR spectroscopy. In toluene solutions and low-temperature glasses, the complexes exist as two forms, which were identified ascis-andtrans-isomers. The proportions of the isomers were determined. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 726–729, April, 1999.     

Synthesis and reactivity of metal-containing monomers

Optically active mixed alkoxy orthotitanates with general formula Ti(OR¹)₂(OR²)(OR³) (R¹=Et, Buⁿ; R²=CH₂CH₂OCOC(Me)=CH₂; R³=menthyl, CH(Me)CH₂Me, CH(Ph)CH(NHMe)Me, CH(C₉H₆N)(C₉H₁₄N)) were obtained for the first time by transesterification. The Ti^IV monomers synthesized were characterized by elemental analysis, ozonolysis, and¹H and¹³C NMR and IR spectroscopy. Polymer products with optical activity were obtained by liquid phase radical copolymerization of Ti^IV-containing monomers. For Part 51, see Ref. 1. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1739–1743, September, 1999.     

Light‐Induced Rearrangement of Thioether‐Substituted Phosphanide Ligands: Scope and Limitations of a Remarkable Isomerization

Treatment of the thioether‐substituted secondary phosphanes R²PH(C₆H₄‐2‐SR¹) [R²=(Me₃Si)₂CH, R¹=Me ( 1_PH ), iPr ( 2_PH ), Ph ( 3_PH ); R²=tBu, R¹=Me ( 4_PH ); R²=Ph, R¹=Me ( 5_PH )] with nBuLi yields the corresponding lithium phosphanides, which were isolated as their THF ( 1 – 5_Pa ) and tmeda ( 1 – 5_Pb ) adducts. Solid‐state structures were obtained for the adducts [R²P(C₆H₄‐2‐SR¹)]Li(L)_n [R²=(Me₃Si)₂CH, R¹=nPr, (L)_n=tmeda ( 2_Pb ); R²=(Me₃Si)₂CH, R¹=Ph, (L)_n=tmeda ( 3_Pb ); R²=Ph, R¹=Me, (L)_n=(THF)_1.33 ( 5_Pa ); R²=Ph, R¹=Me, (L)_n=([12]crown‐4)₂ ( 5_Pc )]. Treatment of 1_PH with either PhCH₂Na or PhCH₂K yields the heavier alkali metal complexes [{(Me₃Si)₂CH}P(C₆H₄‐2‐SMe)]M(THF)_n [M=Na ( 1_Pd ), K ( 1_Pe )]. With the exception of 2_Pa and 2_Pb , photolysis of these complexes with white light proceeds rapidly to give the thiolate species [R²P(R¹)(C₆H₄‐2‐S)]M(L)_n [M=Li, L=THF ( 1_Sa , 3_Sa – 5_Sa ); M=Li, L=tmeda ( 1_Sb , 3_Sb – 5_Sb ); M=Na, L=THF ( 1_Sd ); M=K, L=THF ( 1_Se )] as the sole products. The compounds 3_Sa and 4_Sa may be desolvated to give the cyclic oligomers [[{(Me₃Si)₂CH}P(Ph)(C₆H₄‐2‐S)]Li]₆ (( 3_S )₆) and [[tBuP(Me)(C₆H₄‐2‐S)]Li]₈ (( 4_S )₈), respectively. A mechanistic study reveals that the phosphanide–thiolate rearrangement proceeds by intramolecular nucleophilic attack of the phosphanide center at the carbon atom of the substituent at sulfur. For 2_Pa / 2_Pb , competing intramolecular β‐deprotonation of the n‐propyl substituent results in the elimination of propene and the formation of the phosphanide–thiolate dianion [{(Me₃Si)₂CH}P(C₆H₄‐2‐S)]^2?.     

Iminophosphines: synthesis, formation of 2,3-dihydro-1H-benzo[1,3]azaphosphol-3-ium salts and N-(pyridin-2-yl)-2-diphenylphosphinoylaniline, coordination chemistry and applications in platinum group catalyzed Suzuki coupling reactions and hydrosilylations

The aprotic and protic bi- and multidentate iminophosphines 2-Ph₂PC₆H₄N=CR¹R² (R¹=H, R²=Ph=2a; R¹=Me R²=Ph=2b; R¹=H, R²=2-thienyl=2c; R¹=H, R²=C₆H₄-2-PPh₂=2d; R¹=H, R²=C₆H₄-2-OH=2e, R¹=H, R²=C₆H₄-2-OH-3-Bu^t=2f; R¹=H, R²=CH₂C(O)Me=2g) have been prepared by the acid catalyzed condensation of 2-(diphenylphosphino)aniline with the corresponding aldehyde–ketone. Iminophosphine 2d can be reduced with sodium cyanoborohydride to give the corresponding amino-diphosphine 2-Ph₂PC₆H₄N(H)CH₂C₆H₄-2-PPh₂ (2h). In the presence of a stoichiometric quantity of acid, 2-(diphenylphosphino)aniline reacts in an unexpected manner with benzaldehyde, salicylaldehyde, or acetophenone to give the corresponding 2,3-dihydro-1H-benzo[1,3]azaphosphol-3-ium salts and with pyridine-2-carboxaldehyde to give N-(pyridin-2-ylmethyl)-2-diphenylphosphinoylaniline, the latter of which has been characterized by single-crystal X-ray crystallography, as its palladium dichloride derivative. The attempted condensation of 2-(diphenylphosphino)aniline with pyridine-2-carboxaldehyde to give the corresponding pyridine-functionalized iminophosphine resulted in an unusual transformation involving the diastereoselective addition of two equivalents of aldehyde to give 1,2-dipyridin-2-yl-2-(o-diphenylphosphinoyl)phenylamino-ethanol, which has been characterized by a single-crystal X-ray structure determination. The bidentate iminophosphine 2-Ph₂PC₆H₄N=C(H)Ph reacts with [(cycloocta-1,5-diene)PdClX] X=Cl, Me) to give [Pd{2-Ph₂PC₆H₄N=C(H)Ph}ClX] and the imino-diphosphine 2-Ph₂PC₆H₄N=C(H)C₆H₄-PPh₂ reacts with [(cycloocta-1,5-diene)PdClMe] to give [Pd{2-Ph₂PC₆H₄N=C(H)C₆H₄---PPh₂}ClMe] and each has been characterized by single-crystal X-ray crystallography. The monobasic iminophosphine 2-Ph₂PC₆H₄N=C(Me)CH₂C(O)Me reacts with [Ni(PPh₃)₂Cl₂] in the presence of NaH to give the phosphino–ketoiminate complex [Ni{2-Ph₂PC₆H₄N=C(Me)CHC(O)Me}Cl], which has been structurally characterized. Mixtures of iminophosphines 2a–h and a palladium source catalyze the Suzuki cross coupling of 4-bromoacetophenone with phenyl boronic acid. The efficiency of these catalysts show a marked dependence on the palladium source, catalysts formed from [Pd₂(OAc)₆] giving consistently higher conversions than those formed from [Pd₂(dba)₃] and [PdCl₂(MeCN)₂]. Catalysts formed from neutral bi- and terdentate iminophosphines 2a–d gave significantly higher conversions than those formed from their monobasic counterparts 2e–f. Notably, under our conditions the conversions obtained with 2a–c compare favorably with those of the standards; catalysts formed from tris(2-tolyl)phosphine and tris(2,4-di-tert-butylphenyl)phosphite and a source of palladium. In addition, mixtures of [Ir(COD)Cl]₂ and 2a–h are active for the hydrosilylation of acetophenone; in this case catalysts formed from monobasic iminophosphines 2e–f giving the highest conversions.