Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes

Sara R.M.M. De Aguiar, Özgür Öztopcu, Berthold Stöger, Kurt Mereiter, Luis F. Veiros, Ernst Pittenauer, Günter Allmaier, Karl Kirchner

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Abstract

In the present study a series of six-coordinate neutral 16e halocarbonyl Mo(ii) complexes of the type [Mo(PNPMe-iPr)(CO)X2] (X = I, Br, Cl), featuring the PNP pincer ligand N,N′-bis(diisopropylphosphino)-N,N′-dimethyl-2,6-diaminopyridine (PNPMe-iPr), were prepared and fully characterized. The synthesis of these complexes was accomplished by different methodologies depending on the halide ligands. For X = I and Br, [Mo(PNPMe-iPr)(CO)I2] and [Mo(PNPMe-iPr)(CO)Br2] were obtained by reacting [Mo(PNPMe-iPr)(CO)3] with stoichiometric amounts of I2 and Br2, respectively. In the case of X = Cl, [Mo(PNPMe-iPr)(CO)Cl2] was afforded by the reaction of [Mo(CO)4(μ-Cl)Cl]2 with 1 equiv. of PNPMe-iPr. The equivalent procedure also worked for X = Br. The modification of the 2,6-diaminopyridine scaffold by introducing NMe instead of NH spacers between the aromatic pyridine ring and the phosphine moieties changed the steric properties of the PNP-iPr ligand significantly. While in the present case exclusively neutral six-coordinate complexes of the type [Mo(PNPMe-iPr)(CO)X2] were obtained, with the parent PNP-iPr ligand, i.e. featuring NH spacers, cationic seven-coordinate complexes of the type [Mo(PNP-iPr)(CO)3X]X were afforded. Upon treatment of [Mo(PNPMe-iPr)(CO)X2] (X = Br, Cl) with Ag+ in CH3CN, the cationic complexes [Mo(PNPMe-iPr)(CO)(CH3CN)X]+ were formed. Halide abstraction from [Mo(PNPMe-iPr)(CO)Cl2] in THF-CH2Cl2 afforded [Mo(PNPMe-iPr)(CO)(THF)Cl]+. In keeping with the facile synthesis of monocationic complexes preliminary ESI-MS and DFT/B3LYP studies revealed that one halide ligand in complexes [Mo(PNPMe-iPr)(CO)X2] is labile forming cationic fragments [Mo(PNPMe-iPr)(CO)X]+ which react with molecular oxygen in parallel pathways to yield mono and dioxo Mo(iv) and Mo(vi) species. Structures of representative complexes were determined by X-ray single crystal analyses. This journal is

Original languageEnglish
Pages (from-to)14669-14679
Number of pages11
JournalDalton Transactions
Volume43
Issue number39
DOIs
Publication statusPublished - 21 Oct 2014

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

De Aguiar, S. R. M. M., Öztopcu, Ö., Stöger, B., Mereiter, K., Veiros, L. F., Pittenauer, E., ... Kirchner, K. (2014). Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes. Dalton Transactions, 43(39), 14669-14679. https://doi.org/10.1039/c4dt01932f

Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes. / De Aguiar, Sara R.M.M.; Öztopcu, Özgür; Stöger, Berthold; Mereiter, Kurt; Veiros, Luis F.; Pittenauer, Ernst; Allmaier, Günter; Kirchner, Karl.

In: Dalton Transactions, Vol. 43, No. 39, 21.10.2014, p. 14669-14679.

Research output: Contribution to journalArticle

De Aguiar, SRMM, Öztopcu, Ö, Stöger, B, Mereiter, K, Veiros, LF, Pittenauer, E, Allmaier, G & Kirchner, K 2014, 'Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes', Dalton Transactions, vol. 43, no. 39, pp. 14669-14679. https://doi.org/10.1039/c4dt01932f
De Aguiar SRMM, Öztopcu Ö, Stöger B, Mereiter K, Veiros LF, Pittenauer E et al. Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes. Dalton Transactions. 2014 Oct 21;43(39):14669-14679. https://doi.org/10.1039/c4dt01932f
De Aguiar, Sara R.M.M. ; Öztopcu, Özgür ; Stöger, Berthold ; Mereiter, Kurt ; Veiros, Luis F. ; Pittenauer, Ernst ; Allmaier, Günter ; Kirchner, Karl. / Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes. In: Dalton Transactions. 2014 ; Vol. 43, No. 39. pp. 14669-14679.
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abstract = "In the present study a series of six-coordinate neutral 16e halocarbonyl Mo(ii) complexes of the type [Mo(PNPMe-iPr)(CO)X2] (X = I, Br, Cl), featuring the PNP pincer ligand N,N′-bis(diisopropylphosphino)-N,N′-dimethyl-2,6-diaminopyridine (PNPMe-iPr), were prepared and fully characterized. The synthesis of these complexes was accomplished by different methodologies depending on the halide ligands. For X = I and Br, [Mo(PNPMe-iPr)(CO)I2] and [Mo(PNPMe-iPr)(CO)Br2] were obtained by reacting [Mo(PNPMe-iPr)(CO)3] with stoichiometric amounts of I2 and Br2, respectively. In the case of X = Cl, [Mo(PNPMe-iPr)(CO)Cl2] was afforded by the reaction of [Mo(CO)4(μ-Cl)Cl]2 with 1 equiv. of PNPMe-iPr. The equivalent procedure also worked for X = Br. The modification of the 2,6-diaminopyridine scaffold by introducing NMe instead of NH spacers between the aromatic pyridine ring and the phosphine moieties changed the steric properties of the PNP-iPr ligand significantly. While in the present case exclusively neutral six-coordinate complexes of the type [Mo(PNPMe-iPr)(CO)X2] were obtained, with the parent PNP-iPr ligand, i.e. featuring NH spacers, cationic seven-coordinate complexes of the type [Mo(PNP-iPr)(CO)3X]X were afforded. Upon treatment of [Mo(PNPMe-iPr)(CO)X2] (X = Br, Cl) with Ag+ in CH3CN, the cationic complexes [Mo(PNPMe-iPr)(CO)(CH3CN)X]+ were formed. Halide abstraction from [Mo(PNPMe-iPr)(CO)Cl2] in THF-CH2Cl2 afforded [Mo(PNPMe-iPr)(CO)(THF)Cl]+. In keeping with the facile synthesis of monocationic complexes preliminary ESI-MS and DFT/B3LYP studies revealed that one halide ligand in complexes [Mo(PNPMe-iPr)(CO)X2] is labile forming cationic fragments [Mo(PNPMe-iPr)(CO)X]+ which react with molecular oxygen in parallel pathways to yield mono and dioxo Mo(iv) and Mo(vi) species. Structures of representative complexes were determined by X-ray single crystal analyses. This journal is",
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T1 - Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes

AU - De Aguiar, Sara R.M.M.

AU - Öztopcu, Özgür

AU - Stöger, Berthold

AU - Mereiter, Kurt

AU - Veiros, Luis F.

AU - Pittenauer, Ernst

AU - Allmaier, Günter

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N2 - In the present study a series of six-coordinate neutral 16e halocarbonyl Mo(ii) complexes of the type [Mo(PNPMe-iPr)(CO)X2] (X = I, Br, Cl), featuring the PNP pincer ligand N,N′-bis(diisopropylphosphino)-N,N′-dimethyl-2,6-diaminopyridine (PNPMe-iPr), were prepared and fully characterized. The synthesis of these complexes was accomplished by different methodologies depending on the halide ligands. For X = I and Br, [Mo(PNPMe-iPr)(CO)I2] and [Mo(PNPMe-iPr)(CO)Br2] were obtained by reacting [Mo(PNPMe-iPr)(CO)3] with stoichiometric amounts of I2 and Br2, respectively. In the case of X = Cl, [Mo(PNPMe-iPr)(CO)Cl2] was afforded by the reaction of [Mo(CO)4(μ-Cl)Cl]2 with 1 equiv. of PNPMe-iPr. The equivalent procedure also worked for X = Br. The modification of the 2,6-diaminopyridine scaffold by introducing NMe instead of NH spacers between the aromatic pyridine ring and the phosphine moieties changed the steric properties of the PNP-iPr ligand significantly. While in the present case exclusively neutral six-coordinate complexes of the type [Mo(PNPMe-iPr)(CO)X2] were obtained, with the parent PNP-iPr ligand, i.e. featuring NH spacers, cationic seven-coordinate complexes of the type [Mo(PNP-iPr)(CO)3X]X were afforded. Upon treatment of [Mo(PNPMe-iPr)(CO)X2] (X = Br, Cl) with Ag+ in CH3CN, the cationic complexes [Mo(PNPMe-iPr)(CO)(CH3CN)X]+ were formed. Halide abstraction from [Mo(PNPMe-iPr)(CO)Cl2] in THF-CH2Cl2 afforded [Mo(PNPMe-iPr)(CO)(THF)Cl]+. In keeping with the facile synthesis of monocationic complexes preliminary ESI-MS and DFT/B3LYP studies revealed that one halide ligand in complexes [Mo(PNPMe-iPr)(CO)X2] is labile forming cationic fragments [Mo(PNPMe-iPr)(CO)X]+ which react with molecular oxygen in parallel pathways to yield mono and dioxo Mo(iv) and Mo(vi) species. Structures of representative complexes were determined by X-ray single crystal analyses. This journal is

AB - In the present study a series of six-coordinate neutral 16e halocarbonyl Mo(ii) complexes of the type [Mo(PNPMe-iPr)(CO)X2] (X = I, Br, Cl), featuring the PNP pincer ligand N,N′-bis(diisopropylphosphino)-N,N′-dimethyl-2,6-diaminopyridine (PNPMe-iPr), were prepared and fully characterized. The synthesis of these complexes was accomplished by different methodologies depending on the halide ligands. For X = I and Br, [Mo(PNPMe-iPr)(CO)I2] and [Mo(PNPMe-iPr)(CO)Br2] were obtained by reacting [Mo(PNPMe-iPr)(CO)3] with stoichiometric amounts of I2 and Br2, respectively. In the case of X = Cl, [Mo(PNPMe-iPr)(CO)Cl2] was afforded by the reaction of [Mo(CO)4(μ-Cl)Cl]2 with 1 equiv. of PNPMe-iPr. The equivalent procedure also worked for X = Br. The modification of the 2,6-diaminopyridine scaffold by introducing NMe instead of NH spacers between the aromatic pyridine ring and the phosphine moieties changed the steric properties of the PNP-iPr ligand significantly. While in the present case exclusively neutral six-coordinate complexes of the type [Mo(PNPMe-iPr)(CO)X2] were obtained, with the parent PNP-iPr ligand, i.e. featuring NH spacers, cationic seven-coordinate complexes of the type [Mo(PNP-iPr)(CO)3X]X were afforded. Upon treatment of [Mo(PNPMe-iPr)(CO)X2] (X = Br, Cl) with Ag+ in CH3CN, the cationic complexes [Mo(PNPMe-iPr)(CO)(CH3CN)X]+ were formed. Halide abstraction from [Mo(PNPMe-iPr)(CO)Cl2] in THF-CH2Cl2 afforded [Mo(PNPMe-iPr)(CO)(THF)Cl]+. In keeping with the facile synthesis of monocationic complexes preliminary ESI-MS and DFT/B3LYP studies revealed that one halide ligand in complexes [Mo(PNPMe-iPr)(CO)X2] is labile forming cationic fragments [Mo(PNPMe-iPr)(CO)X]+ which react with molecular oxygen in parallel pathways to yield mono and dioxo Mo(iv) and Mo(vi) species. Structures of representative complexes were determined by X-ray single crystal analyses. This journal is

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