Polypyrazolates of the heavier group 13 and 14 elements: A review

Muñoz‐Hernández, Miguel‐Ángel; Montiel‐Palma, Virginia

doi:10.1016/j.ica.2009.06.051

Cited by 14 publications

(8 citation statements)

References 60 publications

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“…1 and 2 were synthesized by nucleophilic addition of [Na(Ph 2 pz)] to AlMe 3 and the stepwise addition of 1 and 2 molar equiv of Ph 2 pzH (Scheme 1). 5,18,19 The bimetallic complex [Ph 2 pzAlMe 2 ] 2 20,21…”

Section: Resultsmentioning

confidence: 99%

“…1 and 2 were synthesized by nucleophilic addition of [Na(Ph 2 pz)] to AlMe 3 and the stepwise addition of 1 and 2 molar equiv of Ph 2 pzH (Scheme ). ,, The bimetallic complex [Ph 2 pzAlMe 2 ] 2 , ( 1 H NMR, benzene- d 6 : δ 7.42, 7.03, 6.26, −0.66) is a minor side product (∼10% from 1 H NMR integration) of the reaction, albeit 1 was isolated analytically pure in 75% yield by crystallization in a 10:1 pentane-THF solution at ambient temperature. Complex 2 is readily obtained in 82% yield by reacting 1 with Ph 2 pzH at 90 °C in toluene.…”

Section: Resultsmentioning

confidence: 99%

“…In stark contrast to the ubiquitous poly(pyrazolyl)borates [1][2][3][4] very few reports of the heavier aluminum analogs are known [5][6] . In addition to easy tuning of steric and electronic properties promoted by the rich pyrazole chemistry, the change from boron to aluminum would be highly valuable due to the availability of ligands with wider bites and redox activity.…”

Section: Introductionmentioning

confidence: 99%

“…In stark contrast to the ubiquitous poly(pyrazolyl)borates, − very few reports of the heavier aluminum analogues are known. , In addition to easy tuning of steric and electronic properties promoted by the rich pyrazole chemistry, the change from boron to aluminum would be highly valuable due to the availability of ligands with wider bites and redox activity. Although the first report on such a ligand system dates to the 1970s, it was not until a few years ago that one of us reported the first authenticated sodium poly(pyrazolyl)aluminate exhibiting Al–CH 3 bonds .…”

Section: Introductionmentioning

confidence: 99%

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Cyclooctadiene Rh(I) Bis- and Tris(pyrazolyl)aluminate Complexes and Their Catalytic Activity on the Polymerization of Phenylacetylene

et al. 2021

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In this work we report the transfer of alkyl bis and tris(pyrazolyl)aluminates metalloligands to an electron rich organotransition metal center. The 16-electron heterobimetallic complexes of rhodium [Rh(COD){Al(Ph2pz)2Me2}] (3) and [Rh(COD){Al(Ph2pz)3Me}] (4) were obtained by metathesis reaction of the sodium bis (1) and tris(pyrazolyl)aluminate (2) with [RhCl(COD)]2. For 3, 1 H and 13 C NMR in solution along with DFT calculations are consistent with a  2 -coordination mode of the bis(pyrazolyl)aluminate to a square-planar Rh(I) center. The X-ray structure of 4 shows a similar  2 -coordination mode of the tris(pyrazolyl)aluminate to Rh(I) with a pendant pyrazolyl moiety. The attempted synthesis of aluminate-rhodium complexes with R = CF3, t Bu on the pyrazolate ring afforded [Rh(R2pz)(COD)]2 and [R2pzAlMe2]2. Complexes 3 and 4 were investigated as homogenous catalysts in the polymerization of phenylacetylene (PA). Both complexes showed enhanced catalytic activity compared to analogous rhodium poly(pyrazolyl)borates. Optimized gas phase DFT geometries of 3, 4, [Rh(COD){B(Ph2pz)2Me2}], and [Rh(COD){B(Ph2pz)3Me}] were used to compare bite angles, while DFT geometries of 3-CO, 4-CO, [Rh(CO)2{B(Ph2pz)2Me2}], and [Rh(CO)2{B(Ph2pz)3Me}] were employed to probe the electronic situation of rhodium center through IR CO stretching modes. The wider bite angles and the less electron-rich rhodium center of the poly(pyrazolyl)aluminates compared with their borate analogs could be implicated in the better performance of the active catalytic species during polymerization of PA.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cyclooctadiene Rh(I) Bis- and Tris(pyrazolyl)aluminate Complexes and Their Catalytic Activity on the Polymerization of Phenylacetylene

et al. 2021

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“…Poly(pyrazolyl)methane ligands RR’C(Pz) 2 , RC(Pz) 3 and C(Pz) 4 are the neutral analogues of the anionic poly(pyrazolyl)borates [ 1 , 2 , 3 ], where Pz can be either an unsubstituted or C-substituted pyrazolyl unit. They are formally derived by replacing the apical borate anionic moiety [BR] − by the isoelectronic CR group.…”

Section: Introductionmentioning

confidence: 99%

Solventless Synthesis of Poly(pyrazolyl)phenyl-methane Ligands and Thermal Transformation of Tris(3,5-dimethylpyrazol-1-yl)phenylmethane

et al. 2017

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The solventless synthesis of tris(pyrazolyl)phenylmethane ligands of formula C6H5C(PzR2)3 (R = H, Me), starting from PhCCl3 and 3,5-dimethylpyrazole (PzMe2) or pyrazole (Pz) was performed. The sterically crowded C6H5C(PzMe2)3 is thermally transformed into the bis(pyrazolyl)(p-pyrazolyl)phenylmethane ligand PzMe2-C6H4CH(PzMe2)2. In this compound both PzMe2 rings are linked through the N-atom to the methine C-atom. At higher temperatures, the binding mode of PzMe2 changes from N1 to C4. All transformations occurred via quinonoid carbocation intermediates that undergo an aromatic electrophilic substitution on the 4-position of PzMe2. Reaction conditions were established to obtain five tris(pyrazolyl)phenylmethane ligands in moderate to good yields. 1H- and 13C-NMR spectroscopy and X-ray diffraction of single crystals support the proposed structures.

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Steric Effects on the Structures, Reactivity, and Coordination Chemistry of Tris(2‐pyridyl)aluminates

García‐Rodríguez

Wright

2015

Chemistry A European J

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Introducing substituents in the 6-position of the 2-pyridyl rings of tris(pyridyl)aluminate anions, of the type [EtAl(2-py')3 ](-) (py'=a substituted 2-pyridyl group), has a large impact on their metal coordination characteristics. This is seen most remarkably in the desolvation of the THF solvate [EtAl(6-Me-2-py)3 Li⋅THF] to give the monomer [EtAl(6-Me-2-py)3 Li] (1), containing a pyramidal, three-coordinate Li(+) cation. Similar monomeric complexes are observed for [EtAl(6-CF3 -2-py)3 Li] (2) and [EtAl(6-Br-2-py)3 Li] (3), which contain CF3 and Br substituents (R). This steric influence can be exploited in the synthesis of a new class of terminal Al-OH complexes, as is seen in the controlled hydrolysis of 2 and 3 to give [EtAl(OH)(6-R-2-py)2 ](-) anions, as in the dimer [EtAl(OH)(6-Br-2-py)2 Li]2 (5). Attempts to deprotonate the Al-OH group of 5 using Et2 Zn led only to the formation of the zincate complex [LiZn(6-Br-py)3 ]2 (6), while reactions of the 6-Br substituted 3 and the unsubstituted complex [EtAl(2-py)3 Li] with MeOH give [EtAl(OMe)(6-Br-2-py)2 Li]2 (7) and [EtAl(OMe)(2-py)2 Li]2 (8), respectively, having similar dimeric arrangements to 5. The combined studies presented provide key synthetic methods for the functionalization and elaboration of tris(pyridyl)aluminate ligands.

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Polypyrazolates of the heavier group 13 and 14 elements: A review

Cited by 14 publications

References 60 publications

Cyclooctadiene Rh(I) Bis- and Tris(pyrazolyl)aluminate Complexes and Their Catalytic Activity on the Polymerization of Phenylacetylene

Cyclooctadiene Rh(I) Bis- and Tris(pyrazolyl)aluminate Complexes and Their Catalytic Activity on the Polymerization of Phenylacetylene

Solventless Synthesis of Poly(pyrazolyl)phenyl-methane Ligands and Thermal Transformation of Tris(3,5-dimethylpyrazol-1-yl)phenylmethane

Steric Effects on the Structures, Reactivity, and Coordination Chemistry of Tris(2‐pyridyl)aluminates

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