Synthetic Diversity in the Formation of Triazoles from Nitriles and Diazo Compounds Using Metallocenes of Electropositive Metals

Evans, William J.; Montalvo, Elizabeth; Champagne, Timothy M.; DiPasquale, Antonio G.; Rheingold, Arnold L.

doi:10.1021/om8012103

Cited by 38 publications

(47 citation statements)

References 36 publications

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“…The seven-coordinate Ln 3+ ions are ligated by one neutral pyrrole, one amido ligand, one appended amido group, and two cyanide ligands. The 1.145(4) Å of N(5)−C(23) (CN group) in 7 is comparable to the corresponding average distances of 1.164(4) Å in [(C 5 Me 5 ) 2 -La(μ-CN)(NC-SiMe 3 )] 3 , and 1.147 (6) 21 The angles of La(1)−C(23)−N(5) and La(2)−N(5)−C(23) in 7 are 162.1(4)°and 177.0(1)°, approaching linearity, and the analogous angles of 163.5(4)°a nd 175.9(4)°in 8 are found.…”

Section: ■ Results and Discussionmentioning

confidence: 54%

Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

et al. 2014

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A series of lanthanide amido complexes incorporating a neutral pyrrole ligand were synthesized and characterized, and their catalytic activities were studied. Treatment of [(Me 3 Si) 2 N] 3 Ln(μ-Cl)Li(THF) 3 with 1 equiv of [(2,5-Me 2 C 4 H 2 N)CH 2 CH 2 ] 2 NH (1) in toluene afforded the corresponding lanthanide amides with the formula [η 5 :η 1 -(2,5-Me 2 C 4 H 2 N)CH 2 CH 2 ] 2 NLn[N(SiMe 3 ) 2 ] 2 (Ln = La (2), Nd (3)). Reaction of 2 or 3 with N,N′-dicyclohexylcarbodiimide (CyNCNCy) gave the carbodiimide selectively inserted into the appended Ln−N bond products formulated as CyNC{[N,N-(2,5-Me 2 C 4 H 2 N)CH 2 CH 2 ] 2 N}NCyLn[N-(SiMe 3 ) 2 ] 2 (Ln = La (4), Nd (5)). Reactions of the lanthanide amides with Me 3 SiCN were also examined. A mixed reaction of [(Me 3 Si) 2 N] 3 La(μ-Cl)Li(THF) 3 , [(2,5-Me 2 C 4 H 2 N)CH 2 CH 2 ] 2 NH (1), and Me 3 SiCN in toluene at room temperature produced the novel cyano bridged dinuclear lanthanum complex η 5 :η 1 :η 3 -[(2,5-Me 2 C 4 H 2 NCH 2 CH 2 ) 2 N]La[N(SiMe 3 ) 2 ](μ-CN)La[N(SiMe 3 ) 2 ] 3 (6). The stoichiometric reactions of lanthanide amides 2 or 3 with Me 3 SiCN produced the novel trinuclear lanthanum and neodymium complexes {(η 5 :η 1 -[(2,5-Me 2 C 4 H 2 NCH 2 CH 2 ) 2 N]Ln[N(SiMe 3 ) 2 ](μ-CN)} 3 (Ln = La (7), Nd (8)) through selective σ-bond metathesis reaction of the terminal Ln−N (N(SiMe 3 ) 2 ) bond with the Si−C bond of Me 3 SiCN. On the basis of the stoichiometric reactions of complexes 2, or 3 with Me 3 SiCN, complexes 2, 3, 4, 5, 7, and 8 as catalysts for cyanosilylation of ketones were investigated. Results indicated that these complexes displayed a high catalytic activity on addition of Me 3 SiCN to ketones, and the activity of the complexes has the order of 7 ∼ 8 > 2 ∼ 3 ∼ 4 ∼ 5. Thus, complex 7 or 8 was proposed as the active catalyst in the catalytic reaction for the precatalysts of 2 and 3.

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Section: ■ Results and Discussionmentioning

confidence: 54%

Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

et al. 2014

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“…(8)]. [19] With praseodymium, reactivity analogous to that of lanthanum in Equation (7) was observed to produce…”

Section: Resultsmentioning

confidence: 99%

“…(7)], a nitrile that has proven to be susceptible to cyanide formation in the past [Eq. (8)] 19. It seems that the weaker SiC bond of this nitrile is more susceptible to cleavage than Me 3 CCN.…”

Section: Discussionmentioning

confidence: 99%

“…(8)]. [19] It seems that the weaker SiÀC bond of this nitrile is more susceptible to cleavage than Me 3 CCN.…”

Section: Discussionmentioning

confidence: 99%

“…Structural analysis of complexes 10, 11, and 13: Isomorphous complexes 10 [19] and 11 have normal bond parameters for lanthanide metallocenes ( Table 6). As is typical in cyanide-bridged complexes of these heavy metals, the C and N atoms of the cyanide cannot be differentiated and are modeled with 50 % occupancy.…”

Section: Structural Analysis Of Complexmentioning

confidence: 99%

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Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C₅Me₅)₃ML_n] Nitrile and Isocyanide Complexes

Evans

Mueller

2010

Chemistry A European J

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The limits of steric crowding in organometallic metallocene complexes have been examined by studying the synthesis of [(C(5)Me(5))(3)ML(n)] complexes as a function of metal in which L=Me(3)CCN, Me(3)CNC, and Me(3)SiCN. The bis(tert-butyl nitrile) complexes [(C(5)Me(5))(3)Ln(NCCMe(3))(2)] (Ln=La, 1; Ce, 2; Pr, 3) can be isolated with the largest lanthanide metal ions, La(3+), Ce(3+), and Pr(3+). The Pr(3+) ion also forms an isolable mono-nitrile complex, [(C(5)Me(5))(3)Pr(NCCMe(3))] (4), whereas for Nd(3+) only the mono-adduct [(C(5)Me(5))(3)Nd(NCCMe(3))] (5) was observed. With smaller metal ions, Sm(3+) and Y(3+), insertion of Me(3)CCN into the M--C(C(5)Me(5)) bond was observed to form the cyclopentadiene-substituted ketimide complexes [(C(5)Me(5))(2)Ln{NC(C(5)Me(5))(CMe(3))}(NCCMe(3))] (Ln=Sm, 6; Y, 7). With tert-butyl isocyanide ligands, a bis-isocyanide product can be isolated with lanthanum, [(C(5)Me(5))(3)La(CNCMe(3))(2)] (8), and a mono-isocyanide product with neodymium, [(C(5)Me(5))(3)Nd(CNCMe(3))] (9). Silicon-carbon bond cleavage was observed in reactions between [(C(5)Me(5))(3)Ln] complexes and trimethylsilyl cyanide, Me(3)SiCN, to produce the trimeric cyanide complexes [{(C(5)Me(5))(2)Ln(mu-CN)(NCSiMe(3))}(3)] (Ln=La, 10; Pr, 11). With uranium, a mono-nitrile reaction product, [(C(5)Me(5))(3)U(NCCMe(3))] (12), which is analogous to 5, was obtained from the reaction between [(C(5)Me(5))(3)U] and Me(3)CCN, but [(C(5)Me(5))(3)U] reacts with Me(3)CNC through C--N bond cleavage to form a trimeric cyanide complex, [{(C(5)Me(5))(2)U(mu-CN)(CNCMe(3))}(3)] (13).

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Lanthanides: Cyclopentadienyl Compounds

Kresiński

2012

Encyclopedia of Inorganic and Bioinorganic Chemistry

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Cyclopentadienyl complexes were among the first organo— rare earth(III) species to be produced, and their study has burgeoned over the past half‐century due, in part, to improved handling techniques excluding oxygen and moisture. Their synthesis is commonly by means of direct replacement of smaller counterions using agents such as alkali metal cyclopentadienides. This reaction being sterically limiting, the introduction of cyclopentadienide ligands is generally sequential. The interactions between metal and ligand are dominated by electrostatics rather than covalent factors, and thus the predominant mode of bonding is with the metal ion sitting approximately on a planar ligand face, with all five C atoms interacting to approximately the same degree. Since rare earth ionic chemistry is generally electrostatically driven, other ligands may participate in the coordination sphere, according to the available remaining space. Coordination saturation seems to occur with three cyclopentadienyl ligands and two other commonly sized donor atoms such as S, even for the larger, early rare earths. Such ancillary ligands can frequently be accommodated flexibly and reversibly, the cyclopentadienyl ligands adjusting distance and orientation to compensate. For complexes containing three cyclopentadienyl ligands, reactivity is generally limited to such reversible accommodation of ancillary ligands, or removal of ring ligands by protic reagents. For complexes containing two cyclopentadienyl ligands, increased steric space opens up a rich chemistry. Binuclear bridging species become common, and reactions involving insertion or activation of small ligand species become more common: several catalytic cycles are mediated by biscyclopentadienyl rare earth species. Single cyclopentadienyl rare earth complexes are yet more complex in their behavior because of their increased steric openness: however, they do number among them some interesting compounds of hypervalent oxygen and chlorine.

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Synthetic Diversity in the Formation of Triazoles from Nitriles and Diazo Compounds Using Metallocenes of Electropositive Metals

Cited by 38 publications

References 36 publications

Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C₅Me₅)₃ML_n] Nitrile and Isocyanide Complexes

Lanthanides: Cyclopentadienyl Compounds

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Synthetic Diversity in the Formation of Triazoles from Nitriles and Diazo Compounds Using Metallocenes of Electropositive Metals

Cited by 38 publications

References 36 publications

Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

Synthesis, Characterization, and Reactivity of Lanthanide Amides Incorporating Neutral Pyrrole Ligand. Isolation and Characterization of Active Catalyst for Cyanosilylation of Ketones

Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C5Me5)3MLn] Nitrile and Isocyanide Complexes

Lanthanides: Cyclopentadienyl Compounds

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Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C₅Me₅)₃ML_n] Nitrile and Isocyanide Complexes