title: Solventless Synthesis of Poly(pyrazolyl)phenyl-methane Ligands and Thermal Transformation of Tris(3,5-dimethylpyrazol-1-yl)phenylmethane.
abstract: 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 PzMe2rings are linked through the N-atom to the methine C-atom. At higher temperatures, the binding mode of PzMe2changes 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- and13C-NMR spectroscopy and X-ray diffraction of single crystals support the proposed structures.
authors.affiliation: Laboratorio de Química Supramolecular y Nanociencias, Instituto Politécnico Nacional-UPIBI, Av. Acueducto s/n Barrio la Laguna Ticomán, Ciudad de México C.P. 07340, Mexico. edith_rove@hotmail.com.
authors.forename: Edith
authors.initials: E
authors.lastname: Rodríguez-Venegas
authors.affiliation: Laboratorio de Química Supramolecular y Nanociencias, Instituto Politécnico Nacional-UPIBI, Av. Acueducto s/n Barrio la Laguna Ticomán, Ciudad de México C.P. 07340, Mexico. efren1003@yahoo.com.mx.
authors.forename: Efrén V
authors.initials: EV
authors.lastname: García-Báez
authors.affiliation: Facultad de Ciencias Químicas, Universidad de Colima, Km. 9 Carretera Colima-Coquimatlán, Coquimatlán C.P. 28400, Mexico. fjmartin@ucol.mx.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Martínez-Martínez
authors.affiliation: Laboratorio de Química Supramolecular y Nanociencias, Instituto Politécnico Nacional-UPIBI, Av. Acueducto s/n Barrio la Laguna Ticomán, Ciudad de México C.P. 07340, Mexico. alcralmx@yahoo.com.mx.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cruz
authors.affiliation: Laboratorio de Química Supramolecular y Nanociencias, Instituto Politécnico Nacional-UPIBI, Av. Acueducto s/n Barrio la Laguna Ticomán, Ciudad de México C.P. 07340, Mexico. ipadillamar@ipn.mx.
authors.forename: Itzia I
authors.initials: II
authors.lastname: Padilla-Martínez
mesh_terms: D000473:Alkanes / Q000138:chemical synthesis*; D060326:Chemistry Techniques, Synthetic; D006358:Hot Temperature; D008024:Ligands; D008697:Methane / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000473:Alkanes; D008024:Ligands; D009942:Organometallic Compounds; D011720:Pyrazoles; C027635:3,5-dimethylpyrazole; D008697:Methane
keywords: X-ray molecular structure; bis(pyrazolyl)phenylmethane; poly(pyrazolyl)methane; thermal synthesis; three-bladed propeller; tris(pyrazolyl)phenylmethane