[V<sup>IV</sup>O]/[V<sup>V</sup>O]/[V<sup>V</sup>O<sub>2</sub>] Complexes of Trinucleating Ligands: Synthesis, Characterization, Structural Evidence for a Hexanuclear Complex, and Their Catalytic Potential for the Synthesis of Pyrimido[1,2-<i>a</i>]b

Ligands H<sub>6</sub>btzh(fp)<sub>3</sub> (<b>I</b>), H<sub>6</sub>btzh(mp)<sub>3</sub> (<b>II</b>), H<sub>6</sub>btzh(pp)<sub>3</sub> (<b>III</b>), and H<sub>6</sub>btzh(bp)<sub>3</sub> (<b>IV</b>) obtained by the condensation of benzene-1,3,5-tricarbohydrazide (H<sub>3</sub>bthz) and 4-formyl-3-methyl-1-phenyl-5-pyrazolone (Hfp), 4-acetyl-3-methyl-1-phenyl-5-pyrazolone (Hmp), 4-butyryl-3-methyl-1-phenyl-5-pyrazolone (Hpp), and 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone (Hbp) have three tridentate dibasic ONO coordination functionalities. Three different types of trinuclear vanadium complexes have been isolated from these ligands. These are (i) tris{[V<sup>IV</sup>O]<sup>2+</sup>} type [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(fp)<sub>3</sub>}] (<b>1</b>), [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(mp)<sub>3</sub>}] (<b>2</b>), [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(pp)<sub>3</sub>}] (<b>3</b>), and [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(bp)<sub>3</sub>}] (<b>4</b>); (ii) tris{[V<sup>V</sup>O(OMe)]<sup>2+</sup>} type [{V<sup>V</sup>O(OMe)}<sub>3</sub>{btzh(fp)<sub>3</sub>}] (<b>5</b>), [{V<sup>V</sup>O(OMe)}<sub>3</sub>{btzh(mp)<sub>3</sub>}] (<b>6</b>), [{V<sup>V</sup>O(OMe)}<sub>3</sub>{btzh(pp)<sub>3</sub>}] (<b>7</b>), and [{V<sup>V</sup>O(OMe)}<sub>3</sub>{(btzh(bp)<sub>3</sub>)}] (<b>8</b>); and (iii) salts of tris{<i>cis</i>-[V<sup>V</sup>O<sub>2</sub>]<sup>+</sup>} type M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(fp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>9</b>), Cs<sup>+</sup> (<b>10</b>)], M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(mp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>11</b>), Cs<sup>+</sup> (<b>12</b>)], M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(pp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>13</b>), Cs<sup>+</sup> (<b>14</b>)], and M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(bp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>15</b>), Cs<sup>+</sup> (<b>16</b>)]. Different instrumental methods were used to characterize these complexes, including single-crystal X-ray for two of them. Dimerization through [V-(μ-O)-V] interactions of two independent units each of trinuclear <b>8</b> in the solid state gives a unique hexanuclear structure. These complexes catalyze the formation of biologically active pyrimido[1,2-<i>a</i>]benzimidazoles in excellent yields (up to 98%) within 5 min under mild conditions and are better than their mononuclear analogues. An intermediate of this reaction has also been isolated to propose a suitable reaction mechanism, which has further been supported by a DFT study.

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Journal
Inorganic Chemistry
Published
2025-10-08
DOI
https://doi.org/10.1021/acs.inorgchem.5c03567
Primary Topic
Vanadium and Halogenation Chemistry
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article
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[VIVO]/[VVO]/[VVO2] Complexes of Trinucleating Ligands: Synthesis, Characterization, Structural Evidence for a Hexanuclear Complex, and Their Catalytic Potential for the Synthesis of Pyrimido[1,2-a]b

Puneet Gupta, Devesh Kumar Singh, Mannar R. Maurya, Fernando Avecilla et al.
Inorganic Chemistry
Vanadium and Halogenation Chemistry
article

[VIVO]/[VVO]/[VVO2] Complexes of Trinucleating Ligands: Synthesis, Characterization, Structural Evidence for a Hexanuclear Complex, and Their Catalytic Potential for the Synthesis of Pyrimido[1,2-a]b

Puneet Gupta, Devesh Kumar Singh, Mannar R. Maurya, Fernando Avecilla, Sonu Kumar
article en

Abstract

Ligands H<sub>6</sub>btzh(fp)<sub>3</sub> (<b>I</b>), H<sub>6</sub>btzh(mp)<sub>3</sub> (<b>II</b>), H<sub>6</sub>btzh(pp)<sub>3</sub> (<b>III</b>), and H<sub>6</sub>btzh(bp)<sub>3</sub> (<b>IV</b>) obtained by the condensation of benzene-1,3,5-tricarbohydrazide (H<sub>3</sub>bthz) and 4-formyl-3-methyl-1-phenyl-5-pyrazolone (Hfp), 4-acetyl-3-methyl-1-phenyl-5-pyrazolone (Hmp), 4-butyryl-3-methyl-1-phenyl-5-pyrazolone (Hpp), and 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone (Hbp) have three tridentate dibasic ONO coordination functionalities. Three different types of trinuclear vanadium complexes have been isolated from these ligands. These are (i) tris{[V<sup>IV</sup>O]<sup>2+</sup>} type [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(fp)<sub>3</sub>}] (<b>1</b>), [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(mp)<sub>3</sub>}] (<b>2</b>), [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(pp)<sub>3</sub>}] (<b>3</b>), and [{V<sup>IV</sup>O(H<sub>2</sub>O)}<sub>3</sub>{btzh(bp)<sub>3</sub>}] (<b>4</b>); (ii) tris{[V<sup>V</sup>O(OMe)]<sup>2+</sup>} type [{V<sup>V</sup>O(OMe)}<sub>3</sub>{btzh(fp)<sub>3</sub>}] (<b>5</b>), [{V<sup>V</sup>O(OMe)}<sub>3</sub>{btzh(mp)<sub>3</sub>}] (<b>6</b>), [{V<sup>V</sup>O(OMe)}<sub>3</sub>{btzh(pp)<sub>3</sub>}] (<b>7</b>), and [{V<sup>V</sup>O(OMe)}<sub>3</sub>{(btzh(bp)<sub>3</sub>)}] (<b>8</b>); and (iii) salts of tris{<i>cis</i>-[V<sup>V</sup>O<sub>2</sub>]<sup>+</sup>} type M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(fp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>9</b>), Cs<sup>+</sup> (<b>10</b>)], M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(mp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>11</b>), Cs<sup>+</sup> (<b>12</b>)], M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(pp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>13</b>), Cs<sup>+</sup> (<b>14</b>)], and M<sub>3</sub>[(V<sup>V</sup>O<sub>2</sub>)<sub>3</sub>{btzh(bp)<sub>3</sub>}]·6H<sub>2</sub>O [M<sup>+</sup> = K<sup>+</sup> (<b>15</b>), Cs<sup>+</sup> (<b>16</b>)]. Different instrumental methods were used to characterize these complexes, including single-crystal X-ray for two of them. Dimerization through [V-(μ-O)-V] interactions of two independent units each of trinuclear <b>8</b> in the solid state gives a unique hexanuclear structure. These complexes catalyze the formation of biologically active pyrimido[1,2-<i>a</i>]benzimidazoles in excellent yields (up to 98%) within 5 min under mild conditions and are better than their mononuclear analogues. An intermediate of this reaction has also been isolated to propose a suitable reaction mechanism, which has further been supported by a DFT study.

Inorganic ChemistryVol. 64(41)
Universidade da Coruña (ES), Indian Institute of Technology Roorkee (IN), Research Centre in Biological Chemistry of Córdoba (AR)
Openalex Percentile: Top 77%
Vanadium and Halogenation Chemistry
DOISourceOpenAlex
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