- Catecholato complexes of cobalt and nickel with 1,4-disubstituted-1,4-diazabutadiens-1,3 and 1,2-bis(diphenylphosphino)ethane
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Divalent cobalt and nickel form four-coordinate complexes with sterically hindered 3,6-di-tert-butylcatecholato dianion (3,6-DBCat) and neutral bidentate 1,4-disubstituted-1,4-diazabutadiens-1,3 (DAB). Structural study of (1,4-di-tert-butyl-1,4-diazabutadiene-1,3)(3,6-di-tert-butyl-catecolato)nickel and (1,4-bis-(2,6-di-iso-propylphenyl)-2,3-dimethyl-1,4-diazabutadiene-1,3)(3,6-di-tert-butyl-catecolato)cobalt indicates square-planar environment of metals. Chemical one-electron oxidation of nickel complexes proceeds through catecholate ligand and leads to o-semiquinonato adducts. EPR spectral parameters indicate preservation of square-planar configuration after oxidation. Complexes (DAB)M(Cat) (M = Ni, Co) undergo neutral ligand substitution reactions. [Figure not available: see fulltext.]
- Bubnov, Michael P.,Teplova, Irina A.,Druzhkov, Nikolay O.,Fukin, Georgy K.,Cherkasova, Anna V.,Cherkasov, Vladimir K.
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- Synthesis and structure of the Novel 11-vertex rhenacarborane dianion [1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H9] 2- and its reactivity toward cationic transition metal fragments
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Treatment of [NEt4] [6-Ph-nodo-6-CB9H11] in tetrahydrofuran (THF) with BunLi (2 equiv) followed by [ReBr(THF)2(CO)3] gives the title rhenacarborane dianion isolated, by addition of [N(PPh3)2]Cl, as a mixed salt [N(PPh3)2][NEt4][1,1,1-(CO) 3-2-Ph-closo-1,2-ReCB9H9], whose structure was confirmed by X-ray diffraction. The closo 11-vertex dianion reacts readily with several cationic transition metal-ligand fragments, affording products with novel structures in which the electrophilic metal groups are attached exo-polyhedrally to the {closo-1,2-ReCB9} cage system by rhenium-metal bonds supported by three-center two-electron B-H-M linkages. Species prepared include [1,3-{M(dppe)}-3-μ-H-1,1,1-(CO) 3-2-Ph- closo-1,2-ReCB9H8] (M = Ni, Pd, or Pt; dppe = Ph 2PCH2CH2PPh2), N(PPh 3)2][1,3,6-{M(CO)3}-3,6-(μ-H) 2-1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H 7] (M = Mn or Re), and [1,6-{M(PPh3)}-1,7-{M(PPh 3)}-6,7-(μ-H)2-1,1,1-(CO) 3-2-Ph-closo-1,2- ReCB9H7] (M = Cu or Au). Of these, the structures of the platinum-rhenium and dicopper-rhenium species were confirmed by X-ray diffraction.
- Du, Shaowu,Kautz, Jason A.,McGrath, Thomas D.,Stone, F. Gordon A.
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- Kinetics of the Homogeneous and Heterogeneous Coupling of Furfural with Biomass-Derived Alcohols
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The tandem dehydrogenation and aldol condensation of butanol with furfural was investigated over homogeneous and heterogeneous catalysts using kinetics and isotope effects. In the homogeneous system, Ni(dppe)Cl2 catalyzes the transfer dehydrogenation of butanol to the furfural, whereas the aldol condensation of butyraldehyde and furfural takes place over the basic K2CO3 cocatalyst. In the heterogeneous system, a transition-metal-free mixed Mg–Al oxide, both the transfer hydrogenation and aldol condensation take place over the basic sites of the catalyst, and the rate-determining step is the alpha-hydride transfer from the butanol to the furfural.
- Goulas, Konstantinos A.,Gokhale, Amit A.
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- Preparation and structure of nickel complex Ni(dppe)Cl2
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Mononuclear nickel complex Ni(dppe)Cl2 (dppe = Ph 2PCH2CH2PPh2) was prepared by reaction of NiCl2·6H2O and dppe in CH 2Cl2/methanol solution and its structure was determined by single crystal X-ray diffraction analysis. The crystals are monoclinic, space group P21/c with a = 12.228(3), b = 15.235(4), c = 15.294(4) A?, α = 90.00, β = 105.933(4), γ= 90.00°, V = 2739.7(13) A?3, Z = 4, F(000) = 1256, Dc = 1.486 g/cm3, μ = 1.231 cm-1, the final R = 0.0543 and wR = 0.1297. A total of 28157 reflections were collected, of which 6516 were independent (Rint = 0.0620).
- Gao, Wei,Li, Kai,Wang, Xin-Ling
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- A new polymorph, form C, of [1,2-bis(diphenylphosphino)ethane]-dichloronickel(II)
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The title compound, [NiCl2(C26H24P2)], has arisen as a result of the unexpected reduction (hydrogenation) of the trans-1.2-bis(diphenylphosphino)ethene ligand. The hydrothermal reaction conditions have produced a third polymorphic form of the compound which has twofold symmetry, crystallizes in an enantiomer-selective manner and contains an unexpectedly short C-C (ethane) bond. Contacts of the form C-H···Cl are present, one involving alkyl and the other aryl hydrogen, with C···Cl distance of 3.556 (4) and 3.664 (6) A, respectively.
- Davison, Jo C.,Foreman, Mark R. St. J.,Howie, R. Alan,Plater, M. John,Skakle, Janet M. S.
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- A Mild One-Pot Reduction of Phosphine(V) Oxides Affording Phosphines(III) and Their Metal Catalysts
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The metal-free reduction of a range of phosphine(V) oxides employing oxalyl chloride as an activating agent and hexachlorodisilane as reducing reagent has been achieved under mild reaction conditions. The method was successfully applied to the reduction of industrial waste byproduct triphenylphosphine(V) oxide, closing the phosphorus cycle to cleanly regenerate triphenylphosphine(III). Mechanistic studies and quantum chemical calculations support the attack of the dissociated chloride anion of intermediated phosphonium salt at the silicon of the disilane as the rate-limiting step for deprotection. The exquisite purity of the resultant phosphine(III) ligands after the simple removal of volatiles under reduced pressure circumvents laborious purification prior to metalation and has permitted the facile formation of important transition metal catalysts.
- Kapu?niak, ?ukasz,Plessow, Philipp N.,Trzybiński, Damian,Wo?niak, Krzysztof,Hofmann, Peter,Jolly, Phillip Iain
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p. 693 - 701
(2021/04/06)
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- Efficient catalytic transfer hydrogenation reactions of carbonyl compounds by Ni(II)-diphosphine complexes
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The catalytic transfer hydrogenation reactions of a series of aromatic and aliphatic carbonyl compounds were investigated using divalent Ni(II)-diphosphine complexes, [L2NiCl2] (where L2 = 1,1-bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,1-bis(diphenylphosphino)ferrocene (dppf), and N-butyl-N-(diphenylphosphino)-1,1-diphenylphosphinamine (dppba)). This is a single-step reaction in the presence of potassium hydroxide and isopropyl alcohol to afford the corresponding alcohols. This protocol tolerates other sensitive functional groups like olefinic double bonds and also achieves high chemoselectivity. All the reactions were monitored by GC and GC–MS. The plausible mechanism is also discussed. The method reported in the present article is simple, cost-effective, and provides excellent conversions. Nickel-diphosphine complexes appear as a potential alternative to expensive transition metal complexes.
- Venkatesh, Sadhana,Panicker, Rakesh R.,Lenin Kumar, Verdhi,Pavankumar,Viswanath, Nukala,Singh, Shangrila,Desikan, Rajagopal,Sivaramakrishna, Akella
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p. 2963 - 2977
(2020/11/03)
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- Halogen Photoelimination from Monomeric Nickel(III) Complexes Enabled by the Secondary Coordination Sphere
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Endothermic halogen elimination reactions, in which molecular halogen photoproducts are generated in the absence of chemical traps, are rare. Inspired by the proclivity of mononuclear Ni(III) complexes to participate in challenging bond-forming reactions in organometallic chemistry, we targeted Ni(III) trihalide complexes as platforms to explore halogen photoelimination. A suite of Ni(III) trihalide complexes supported by bidentate phosphine ligands has been synthesized and characterized. Multinuclear NMR, EPR, and electronic absorption spectroscopies, as well as single-crystal X-ray diffraction, have been utilized to characterize this suite of complexes as distorted square pyramidal, S = 1/2 mononuclear Ni(III) complexes. All complexes participate in clean halogen photoelimination in solution and in the solid state. Evolved halogen has been characterized by mass spectrometry and quantified chemically. Energy storage via halogen elimination was established by solution-phase calorimetry measurements; in all cases, halogen elimination is substantially endothermic. Time-resolved photochemical experiments have revealed a relatively long-lived photointermediate, which we assign to be a Ni(II) complex in which the photoextruded chlorine radical interacts with a ligand-based aryl group. Computational studies suggest that the observed intermediate arises from a dissociative LMCT excited state. The participation of secondary coordination sphere interactions to suppress back-reactions is an attractive design element in the development of energy-storing halogen photoelimination involving first-row transition metal complexes.
- Hwang, Seung Jun,Anderson, Bryce L.,Powers, David C.,Maher, Andrew G.,Hadt, Ryan G.,Nocera, Daniel G.
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p. 4766 - 4774
(2015/10/28)
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- Trap-Free Halogen Photoelimination from Mononuclear Ni(III) Complexes
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Halogen photoelimination reactions constitute the oxidative half-reaction of closed HX-splitting energy storage cycles. Here, we report high-yielding, endothermic Cl2 photoelimination chemistry from mononuclear Ni(III) complexes. On the basis of time-resolved spectroscopy and steady-state photocrystallography experiments, a mechanism involving ligand-assisted halogen elimination is proposed. Employing ancillary ligands to promote elimination offers a strategy to circumvent the inherently short-lived excited states of 3d metal complexes for the activation of thermodynamically challenging bonds.
- Hwang, Seung Jun,Powers, David C.,Maher, Andrew G.,Anderson, Bryce L.,Hadt, Ryan G.,Zheng, Shao-Liang,Chen, Yu-Sheng,Nocera, Daniel G.
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supporting information
p. 6472 - 6475
(2015/06/08)
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- NICKEL PRE-CATALYSTS AND RELATED COMPOSITIONS AND METHODS
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Described herein are nickel pre-catalysts and related compositions and methods. The nickel pre-catalysts may be activated to form catalysts which may be utilized in organic reactions.
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Page/Page column 40
(2015/05/26)
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- A broadly applicable strategy for entry into homogeneous nickel(0) catalysts from air-stable nickel(II) complexes
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A series of air-stable nickel complexes of the form L2Ni(aryl) X (L = monodentate phosphine, X = Cl, Br) and LNi(aryl)X (L = bis-phosphine) have been synthesized and are presented as a library of precatalysts suitable for a wide variety of nickel-catalyzed transformations. These complexes are easily synthesized from low-cost NiCl2·6H2O or NiBr 2·3H2O and the desired ligand followed by addition of 1 equiv of Grignard reagent. A selection of these complexes were characterized by single-crystal X-ray diffraction, and an analysis of their structural features is provided. A case study of their use as precatalysts for the nickel-catalyzed carbonyl-ene reaction is presented, showing superior reactivity in comparison to reactions using Ni(cod)2. Furthermore, as the precatalysts are all stable to air, no glovebox or inert-atmosphere techniques are required to make use of these complexes for nickel-catalyzed reactions.
- Standley, Eric A.,Smith, Stacey J.,Mueller, Peter,Jamison, Timothy F.
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supporting information
p. 2012 - 2018
(2014/05/20)
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- Iminobisphosphines to (Non-)symmetrical diphosphinoamine ligands: Metal-induced synthesis of diphosphorus nickel complexes and application in ethylene oligomerisation reactions
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We describe the synthesis of a range of novel iminobisphosphine ligands based on a sulfonamido moiety [R1SO2N=P(R2)2-P(R3)2]. These molecules rearrange in the presence of nickel by metal-induced breakage of the P-P bond to yield symmetrical and nonsymmetrical diphosphinoamine nickel complexes of general formula Ni{[P(R2)2]N(SO2R1)P(R3)2}Br2. The complexes can be isolated and are very stable. Upon activation by MAO, these complexes oligomerise ethylene to small chain oligomers (mainly C4-C8) with high productivity. Surprisingly fast codimerisation reactions of ethylene with butenes is observed, leading to a high content of branched C6 products. Alkyl-substituted symmetrical and nonsymmetrical diphosphinoamine nickel complexes have been prepared by using sulfonamido-based iminobisphosphines as ligand promoters. The complexes with basic substituents, activated by methylaluminoxane, oligomerise ethylene to short oligomers (C4-C8) with high activity. Fast codimerisation is observed, leading to highly branched C6 product distribution.
- Boulens, Pierre,Lutz, Martin,Jeanneau, Erwann,Olivier-Bourbigou, Hélène,Reek, Joost N. H.,Breuil, Pierre-Alain R.
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p. 3754 - 3762
(2015/04/27)
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- Halogenolysis of a nickelalactone complex produces β-halo-anhydrides
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Nickelalactone complex [(dppe)Ni{κ2-C,O-CH2CH2C(=O)O}] {dppe = 1,2-bis(diphenylphosphino)ethane} reacts with halogens to form 3-halo-propionic anhydrides, [(dppe)NiX2], and [(dppeO2)3Ni][NiX4] (X = Cl, Br, I). Studies of model complexes [(dppe)Ni(O2CtBu)2] and [(dppe)NiBr(O2CtBu)] suggest that oxidation to NiIII and P-O reductive elimination are key steps in this reaction.
- Zarkesh, Ryan A.,Hopkins, Michael D.,Jordan, Richard F.
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supporting information
p. 5491 - 5494
(2015/03/30)
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- Iminobisphosphines to (non-)symmetrical diphosphinoamine ligands: Metal-induced synthesis of diphosphorus nickel complexes and application in ethylene oligomerisation reactions
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We describe the synthesis of a range of novel iminobisphosphine ligands based on a sulfonamido moiety [R1SO2N=P(R 2)2-P(R3)2]. These molecules rearrange in the presence of nickel by metal-induced breakage of the P-P bond to yield symmetrical and nonsymmetrical diphosphinoamine nickel complexes of general formula Ni{[P(R2)2]N(SO2R 1)P(R3)2}Br2. The complexes can be isolated and are very stable. Upon activation by MAO, these complexes oligomerise ethylene to small chain oligomers (mainly C4-C 8) with high productivity. Surprisingly fast codimerisation reactions of ethylene with butenes is observed, leading to a high content of branched C6 products. Copyright
- Boulens, Pierre,Lutz, Martin,Jeanneau, Erwann,Olivier-Bourbigou, Hélène,Reek, Joost N. H.,Breuil, Pierre-Alain R.
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p. 3754 - 3762
(2014/08/18)
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- Process design and scale-up of the synthesis of 2,2′:5′,2′-terthienyl
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The objective of this study was the design of a scaleable process for the synthesis of 3-4 mol of α-terthienyl from 2,5-dibromothiophene and thienylmagnesium bromide in a 10-L stirred tank reactor. In THF the Grignard reagent, thienylmagnesium bromide, was readily formed from 2-bromothiophene and magnesium. To avoid crystallization the maximal concentration was limited to 1.4 M. Furthermore, the novel combination of THF and NiCl2[bis(diphenylphosphino)benzene] allows for fast double coupling of the Grignard reagent with 2,5-dibromothiophene. The concentration of catalyst could be limited to 0.5 mol % based on the amount of 2,5-dibromothiophene. An adapted workup procedure was developed, in which n-octane was used to separate the magnesium salts from the desired product. The reaction was performed in a (semi)batch-wise operated reactor. A global model for the coupling step proved to predict the results at 0.1-, 1-, and 10-L scales very accurately. The heat of reaction evolved in the coupling step was valorized and could be handled easily. Mixing of the feed stream and the reactor content proved to be another important factor in the scaling-up of the α-terthienyl synthesis.
- Smeets,Meijer,Meuldijk,Vekemans,Hulshof
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- Self-assembly and anion encapsulation properties of cavitand-based coordination cages
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Two novel classes of cavitand-based coordination cages 7a-j and 8a-d have been synthesized via self-assembly procedures. The main factors controlling cage self-assembly (CSA) have been identified in (i) a P-M-P angle close to 90° between the chelating ligand and the metal precursor, (ii) Pd and Pt as metal centers, (iii) a weakly coordinated counterion, and (iv) preorganization of the tetradentate cavitand ligand. Calorimetric measurements and dynamic 1H and 19F NMR experiments indicated that CSA is entropy driven. The temperature range of the equilibrium cage-oligomers is determined by the level of preorganization of the cavitand component. The crystal structure of cage 7d revealed the presence of a single triflate anion encapsulated. Guest competition experiments revealed that the encapsulation preference of cages 7b,d follows the order BF4- > CF3SO3- ? PF6- at 300 K. ES-MS experiments coupled to molecular modeling provided a rationale for the observed encapsulation selectivities. The basic selectivity pattern, which follows the solvation enthalpy of the guests, is altered by size and shape of the cavity, allowing the entrance of an ancillary solvent molecule only in the case of BF4-.
- Fochi,Jacopozzi,Wegelius,Rissanen,Cozzini,Marastoni,Fisicaro,Manini,Fokkens,Dalcanale
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p. 7539 - 7552
(2007/10/03)
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- The syntheses, 31P{1H} NMR spectra and cyclic voltammetry of trinuclear [Pd2M(μ3-Se)2(dppe)3] 2+ {M = Ni or Pt; dppe = 1,2-bis(diphenylphoshino)ethane}
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Trinuclear [Pd2M(μ3-Se)2(dppe)3] 2+ (M = Ni or Pt) and pentanuclear [M′{Pd2(μ3-Se)2(dppe)2} 2]2+ (M′ = Ni, Pd or Pt) clusters have been prepared using a metalloligand [Pd2(μ-Se)2(dppe)2] and characterized by 31P{1H} NMR spectroscopy and cyclic voltammetry. [Pd2Ni(μ3-Se)2(dppe)3] 2+ gives two chemically reversible couples, [Pd2Pt(μ3-Se)2(dppe)3] 2+ exhibits one chemically reversible couple and pentanuclear clusters show three couples in each cyclic voltammogram of the reduction process at 255 K. The redox behavior of the clusters is discussed.
- Matsumoto, Keiji,Kotoku, Naho,Shizuka, Takeshi,Tanaka, Rika,Okeya, Seichi
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p. 167 - 170
(2008/10/08)
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- Reaction of [Ni(Ph2PCH2CH2PPh2)2] with DCl: Controlling the formation of HD and D2
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The reaction between anhydrous DCl and [Ni(Ph2PCH2CH2PPh2)2] in dichloromethane produced mixtures of HD and D2. The relative amounts of the dihydrogen isotopomers produced depends on the concentration of acid. Mechanistic investigations showed that the reaction involves initial formation of [NiD(Ph2PCH2CH2PPh2)2]. This deuteriation labilises the nickel to phosphine dissociation. At low concentrations of acid, phosphine chelate ring opening produces [NiCl2(Ph2PCH2CH2PPh2)] (confirmed by X-ray crystallography) and free Ph2PCH2CH2PPh2 together with HD (65 ± 5) and D2 (35 ± 5%). The hydrogen atom of HD originates from a phosphine ligand. At high concentrations of acid the rate of attack of DO at [NiD(Ph2PCH2CH2PPh2 2)2]+ becomes faster than phosphine chelate ring opening and results in the formation of [Ni(Ph2PCH2CH2PPh2) 2]Cl2 and predominantly D2. Experimentally, the highest concentration of DC1 that can be used without appreciable decomposition of the complex is 0. 2 mol dm 3. At this concentration of acid the dihydrogen isotopomer distribution is HD (35 ± 5) and D2 (65 ± 5%); however, analysis of the product distribution indicates that at much higher acid concentrations D2 could be the exclusive isotopomer.
- Davies, Sian C.,Henderson, Richard A.,Hughes, David L.,Oglieve, Kay E.
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p. 425 - 431
(2007/10/03)
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- Dimorphs of ethane>dichloronickel(II)
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The two known forms, A and B, of dichloronickel(II), , were synthesized and identified by IR spectroscopy.The spectra showed that form A had a lower symmetry than form B.The forms were also found to differ by solid-state 31P NMR spectroscopy and powder X-ray diffraction, but the solution properties were identical.The IR spectrum of the dichloromethane solvate of was the same as that of form B but with a strong additional band due to CH2Cl2.The X-ray diffraction pattern from this sample matched that calculated for a previously published crystal structure of *CH2Cl2, thus identifying the form used in that work.Crystals of form A obtained from acetone were used for a single-crystal X-ray structure determination.Comparison of the molecular structures showed that both forms have the same chelate-ring conformation (δ) but differ in the orientations of the phenyl rings.There is a non-crystallographic two-fold axis in form B which is absent from A, explaining the additional bands present in the IR spectrum of the latter.Solid-state 31P NMR was better than IR spectroscopy at distinguishing the two forms from each other and from mixtures.
- Busby, Richard,Hursthouse, Michael B.,Jarrett, Penelope S.,Lehmann, Christian W.,Malik, K. M. Abdul,Phillips, Coral
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p. 3767 - 3770
(2007/10/02)
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- ORGANIC CHEMISTRY OF SUBVALENT TRANSITION METAL COMPLEXES XI. OXIDATIVE ADDITIONS OF NICKEL(0) COMPLEXES TO CARBON-CARBON BONDS IN ALKYNES: NICKELIRENES AND NICKELOLES AS CATALYTIC CARRIERS IN THE OLIGOMERIZATION OF ALKYNES
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The formation of 2,3,4,5-tetraphenylnickelole-bis(triphenylphosphine) (IIIa) and 2,3,4,5-tetraphenylnickelole-bis(1,2-diphenylphosphino)ethane (IIIb), either from (E,E)-1,2,3,4-tetraphenyl-1,3-butadien-1,4-ylidenedilithium (I) and the corresponding nickel(II) chloride-phosphine complexes (II) or from the reduction of η4-tetraphenylcyclobutadienenickel(II) bromide dimer (XII) in the presence of phosphines, proceeds in good yields.Nickelole IIIa displays physical and chemical properties consistent with its structure and is a catalyst for the trimerization of diphenylacetylene.Nickelole IIIb is a highly associated structure but in its chemical response to alkynes, HOAc, O2, Br2, NaAlEt2H2 and heat displays the properties of a nickelole, rather than a cyclobutadienenickel(0) complex.Attempts to generate IIIb photochemically from η4-1,5-cyclooctadiene(η4-tetraphenylcyclopentadienone)nickel and diphos failed, but it was shown that structural types, such as η4-tetraphenylcyclopentadienone(diphos)nickel (a model for the structure suggested by Hoberg and Richter for IIIb), are unstable.Oligomerizations of diphenylacetylene by bis(1,5-cyclooctadiene)nickel were retarded by conducting the reaction in THF or in the presence of diphos.This retardation permitted the interception of products (cis-stilbene and (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene)diagnostic for the intermediacy of nickelirenes and nickeloles.Deuterium labeling verified the presence of carbo-nickel bonds.These trapping experiments, together with findings on the thermal behavior of nickeloles, are combined into a comprehensive view of the cyclotrimerization, cyclotetramerization and linear polymerization of alkynes by nickel(0).
- Eisch, John J.,Galle, James E.,Aradi, Allen A.,Boleslawski, Marek P.
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p. 399 - 416
(2007/10/02)
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- Reactions of Dialkylnickel(II) Complexes NiR2L2 with Alkyl (or Aryl) Halides, R'COY (Y=Cl, Br, OPh, OCOPh), and CS2
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Reactions of Ni(CH3)2(bpy) (1), Ni(C2H5)2(bpy) (2) (bpy=2,2'-bipyridine), trans-Ni(CH3)2(triethylphosphine)2 (3), Ni(CH3)2(1,2-bis(diphenylphosphino)ethane) (4), and Ni(CH3)2(1,3-bis(diphenylphosphino)propane) (5) with alkyl or aryl halides, R'COY (Y=Cl, Br, OC6H5, OCOC6H5), and CS2 have been investigated.The reactions of NiR2L2 with alkyl or aryl halides are classified into three types of reactions by their reaction products: Type A: NiR2L2 + R'X ->NiX(R')L2 + R-R, Type B: NiR2L2 + R'X -> alkane (RH) + olefin (R'(-H)), and Type C: NiR2L2 + R'X -> NiR(X)L2 + R-R'.Complexes 1 and 2 undergo mainly Type A reaction.Complex 3 gives Type A reaction product on treatment with C6H5Br, but it gives Type B reaction product on treatment with C2H5Br.On the other hand, 4 undergoes Type C reaction on interaction with C6H5Cl.The reactions with R'COY (Y=Cl, Br, OPh, OCOPh) are classiffed into two types of reactions by their reaction products: Type D: NiR2L2 + R'COY -> NiY(R)L2 + RCOR' and Type E: NiR2L2 + R'COY -> NiY(R')L2 + RCOR.Complexes 1-3 undergo mainly Type D reaction, whereas complexes 4 and 5 mainly Type E reaction.The diffrence in the reaction route is discussed on the basis of presence or absence of vacant coordination site for attack by R'COY.The reaction of 4 with CS2 affords Ni(CS2)(1,2-bis(diphenylphoshino)ethane) with evolution of a reductive elimination product, ethane, whereas the reaction of 3 with CS2 gives a 1:1 adduct of 3 and CS2.
- Yamamoto, Takakazu,Kohara, Teiji,Osakada, Kohtaro,Yamamoto, Akio
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p. 2147 - 2153
(2007/10/02)
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- Ditertiary phosphine complexes of nickel. Spectral, magnetic, and proton resonance studies. A planar-tetrahedral equilibrium
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A number of complexes of nickel in oxidation states 0, II, and III with the ditertiary phosphines (C6H5)2P(CH2)nP(C 6H5)2 (n = 1, 2, or 3) are reported and studied by spectral and magnetic methods. In solution in organic solvents complexes of the type Ni[(C6H5)2P(CH2)nP(C 6H5)2]X2 where X = Br or I and n = 2 remain diamagnetic. The analogous complexes with n = 3 show a square-planar (diamagnetic)-tetrahedral (paramagnetic) equilibrium in solution. Isotropic proton magnetic resonance shifts were observed in these systems and thermodynamic parameters for the equilibrium were obtained from the temperature dependences of these shifts. The epr spectrum of polycrystalline Ni[(C6H5)2P(CH2)3P(C 6H5)2]Br3 shows an isotropic signal at g = 2.218.
- Van Hecke, Gerald R.,Horrocks Jr., William DeW.
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p. 1968 - 1974
(2008/10/08)
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