η2-acrylonitrilecyclopentadienyldicarbonyliron(II) tetrafluoroborate: an unusual high-valent transition metal complex

Rosenblum, M.; Turnbull, Mark M.; Βέγυμ, Μστ. Εσμάτ Αρα

doi:10.1016/0022-328x(87)80326-1

Cited by 14 publications

(4 citation statements)

References 24 publications

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“…Several 1 H NMR-experiments have been carried out for complex 1a-NCCH 3 at different temperatures in CD 2 Cl 2 to examine the exchange of acetonitrile by acrylonitrile and insertion of acrylonitrile into Pd-Me. The exchange of acetonitrile by acrylonitrile (AN) was monitored by observing the signals of coordinated AN and free AN …”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, the nitrile function is a relatively good donor and though complexes of AN exhibiting bonding via the olefinic π electrons are known, N-bound isomers are energetically competitive, particularly for hard metals. Little is known regarding the barrier to isomerization between N-bound and π-bound AN isomers, and when N-bound complexes dominate, insertion is precluded . When π bonding is accessible, kinetically or thermodynamically, products consistent with 2,1 AN insertion into M−P or M−C bonds have led authors to invoke this as a mechanistic possibility but direct observation of these reactions has not, to our knowledge, been reported.…”

Section: Introductionmentioning

confidence: 99%

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Insertion of Acrylonitrile into Palladium Methyl Bonds in Neutral and Anionic Pd(II) Complexes

et al. 2005

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The reactions of a series of Pd(II) methyl compounds of general formula LPd(NCCH(3))CH(3), where L is a bulky phenoxydiazene or phenoxyaldimine ligand with the polar olefin acrylonitrile (AN), are reported. The compounds react with an excess of AN to give the products of 2,1 insertion into the Pd-Me bond, yielding dimers and/or trimers which feature bridging alpha-cyano groups. The reactions were studied by low temperature (1)H NMR spectroscopy, revealing an initial formation of compounds featuring N-bound AN, which isomerized to an (unobserved) pi-bound species that rapidly underwent 2,1 insertion into the Pd-Me bond. Intermediate oligomeric complexes retaining a Pd-Me function were observed at low [AN] in these reactions. Under pseudo first-order conditions, k(obs) values of 8.5 x 10(-5) to 2.68 x 10(-3) M(-1) (-22 degrees C to 10 degrees C, 100 equiv of AN) and activation parameters of DeltaH++ = 14.4(5) kcal mol(-1) and DeltaS++ = -19(5) eu were obtained in one case. Comparison of the overall rates of insertion between two LPd(NCCH(3))CH(3), differing in the overall charge on the supporting ligand L, showed that the complex bearing a negatively charged ligand reacts with AN twice as fast as one with no anionic charge. The rates of insertion in both of these complexes are significantly faster than reported rates for analogous reactions in cationic Pd(II) derivatives, indicating that increasing the negative charge on the complex enhances the rate of AN insertion. These results provide fundamental mechanistic insights into a crucial reaction for incorporation of polar comonomers into alpha olefins via a coordination polymerization mechanism.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Insertion of Acrylonitrile into Palladium Methyl Bonds in Neutral and Anionic Pd(II) Complexes

et al. 2005

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“…The requirement for N/π isomerization will increase the overall insertion barrier in such cases. N/π- isomerization was observed for CpFe(CO) 2 (AN) + . Nitriles are known to inhibit ethylene polymerization by α-diimine catalysts …”

Section: Introductionmentioning

confidence: 96%

Acrylonitrile Insertion Reactions of Cationic Palladium Alkyl Complexes

Foley

Burns

et al. 2005

J. Am. Chem. Soc.

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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.

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“…New syntheses and reactions of organoiron complexes are recorded in numerous recent publications. Some of them are: synthesis and reactions of η 2 -acrylonitrilecyclopentadienyldicarbonyliron(II) tetrafluoroborate complexes [ 290 , 598 ], synthesis of bis(η 3 -allyl)iron complexes containing basic phosphines [ 599 ]; also, synthesis of η 6 -(biphenyl)-η 5 -(cyclopentadienyl)iron(II) hexa-fluorophosphates [ 600 ], and synthesis of a new cluster containing CH 3 C = C=CH 2 triiron-dirhodium ligand [ 601 ]. New iron-hydroperoxide reactions (Fenton chemistry) have been recently reported [ 602 ].…”

Section: Miscellaneous Recent Resultsmentioning

confidence: 99%

New chemical and stereochemical applications of organoiron complexes

Fatiadi

1991

J. RES. NATL. INST. STAN.

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The objective of this review is to provide a current overview of the rapidly developing chemistry of organometallic complexes and particularly organoiron complexes useful in asymmetric and stereoselective reactions. Also covered are stereoselective reactions of α, β-unsaturated acyl ligands bound to the chiral auxiliary [(η5-C5H5) Fe(CO)(PPh3)] and new applications of organoiron complexes in the synthesis of natural products. The mechanistic aspects and stabilizing effects of the Fe(CO)3 group for alkenes or conjugated dienes are discussed. A brief summary of recent work on the special role of iron in biological reactions is also included.

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η2-acrylonitrilecyclopentadienyldicarbonyliron(II) tetrafluoroborate: an unusual high-valent transition metal complex

Cited by 14 publications

References 24 publications

Insertion of Acrylonitrile into Palladium Methyl Bonds in Neutral and Anionic Pd(II) Complexes

Insertion of Acrylonitrile into Palladium Methyl Bonds in Neutral and Anionic Pd(II) Complexes

Acrylonitrile Insertion Reactions of Cationic Palladium Alkyl Complexes

New chemical and stereochemical applications of organoiron complexes

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