Synthesis and oxidation of d6 tungsten pincer complexes: a complete series of tungsten(ii) hydridocarbonyl and halocarbonyl pincer complexes

Wingard, Leah A.; White, Peter S.; Templeton, Joseph L.

doi:10.1039/c2dt30848g

Cited by 17 publications

(22 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Attempts to obtain the analogous fluorine complex [Mo(PNP Me -iPr)(CO)F 2 ] upon addition of 1 equiv. of 1-fluoro-2,4,6-trimethylpyridinium as the tetrafluoroborate salt, which is known to act as net source of "F + " while the BF 4 − counterion donates fluoride ions, 7,9 to a solution of [Mo(PNP Me -iPr)(CO) 3 ] in CH 2 Cl 2 was unsuccessful. It is interesting to note that there was no evidence for the formation of the cationic complexes [Mo(PNP Me -iPr)(CO) 3 X] + (I) as in the case of the PNP-iPr ligand.…”

Section: Resultsmentioning

confidence: 99%

“…HN(SiMe 2 CH 2 PPh 2 ) 2 were described by Templeton and coworkers. 7 We are currently focusing on the synthesis and reactivity of molybdenum complexes containing PNP pincer ligands based on the 2,6-diaminopyridine scaffold. In these ligands the aromatic pyridine ring and the phosphine moieties are connected via NH, N-alkyl, or N-aryl spacers.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes

et al. 2014

View full text Add to dashboard Cite

In the present study a series of six-coordinate neutral 16e halocarbonyl Mo(ii) complexes of the type [Mo(PNP(Me)-iPr)(CO)X2] (X = I, Br, Cl), featuring the PNP pincer ligand N,N'-bis(diisopropylphosphino)-N,N'-dimethyl-2,6-diaminopyridine (PNP(Me)-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(PNP(Me)-iPr)(CO)I2] and [Mo(PNP(Me)-iPr)(CO)Br2] were obtained by reacting [Mo(PNP(Me)-iPr)(CO)3] with stoichiometric amounts of I2 and Br2, respectively. In the case of X = Cl, [Mo(PNP(Me)-iPr)(CO)Cl2] was afforded by the reaction of [Mo(CO)4(μ-Cl)Cl]2 with 1 equiv. of PNP(Me)-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(PNP(Me)-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(PNP(Me)-iPr)(CO)X2] (X = Br, Cl) with Ag(+) in CH3CN, the cationic complexes [Mo(PNP(Me)-iPr)(CO)(CH3CN)X](+) were formed. Halide abstraction from [Mo(PNP(Me)-iPr)(CO)Cl2] in THF-CH2Cl2 afforded [Mo(PNP(Me)-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(PNP(Me)-iPr)(CO)X2] is labile forming cationic fragments [Mo(PNP(Me)-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.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes

et al. 2014

View full text Add to dashboard Cite

show abstract

“…It has to be noted that the formation of halocarbonyl Mo(II) and W(II) complexes of the type [ML(CO) 3 X] (M = Mo, W; X = Cl, Br, I; L = neutral or anionic tridentate ligands such as Cp, Cp*, HCpz 3 , HBpz 3 ) via oxidative addition of X 2 to M(0) complexes [ML(CO) 3 ] is a well-established reaction [4]. As PNP pincer complexes are concerned, most recently Templeton and coworkers described the synthesis of a series of halocarbonyl tungsten pincer complexes featuring the silazane-based PNP pincer-type ligand HN(SiMe 2 CH 2 PPh 2 ) 2 [5].…”

Section: Introductionmentioning

confidence: 99%

A complete series of halocarbonyl molybdenum PNP pincer complexes – Unexpected differences between NH and NMe spacers

Aguiar

Stöger

Pittenauer

et al. 2014

Journal of Organometallic Chemistry

View full text Add to dashboard Cite

In the present study a complete series of seven-coordinate neutral halocarbonyl Mo(II) complexes of the type [Mo(PNPMe-Ph)(CO)2X2] (X = I, Br, Cl, F), featuring the new PNP pincer ligand N,N′-bis(diphenylphosphino)-N,N′-methyl-2,6-diaminopyridine (PNPMe-Ph), 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-Ph)(CO)2I2] and [Mo(PNPMe-Ph)(CO)2Br2] were obtained by reacting [Mo(PNPMe-Ph)(CO)3] with stoichiometric amounts of I2 and Br2, respectively. Alternatively, these complexes were obtained upon treatment of [MoX2(CO)3(CH3CN)2] (X = I, Br) with 1 equiv. of PNPMe-Ph. On the other hand, in the case of X = Cl, [Mo(PNPMe-Ph)(CO)2Cl2] was afforded by the reaction of [Mo(CO)4(μ-Cl)Cl]2 with 1 equiv. of PNPMe-Ph. The equivalent procedure also worked for X = Br. Finally, addition of 1 equiv. of 1-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate to [Mo(PNPMe-Ph)(CO)3] yielded the analogous fluorine complex [Mo(PNPMe-Ph)(CO)2F2]. The modification of the ligand scaffold by introducing a Me group instead of H changed the properties of the PNP-Ph ligand significantly. While in the present case exclusively neutral seven-coordinate complexes of the type [Mo(PNPMe-Ph)(CO)2X2] were obtained, with the parent PNP-Ph ligand, i.e., featuring NH spacers, cationic seven-coordinate complexes of the type [Mo(PNP-Ph)(CO)3X]X were afforded. DFT calculations indicated that the reactions are under thermodynamic control. The structures of representative complexes were determined by X-ray single crystal analyses.

show abstract

“…18 Finally, Templeton and co-workers described the synthesis of a series of hydrido carbonyl and halo carbonyl tungsten pincer complexes featuring the silazane-based PNP pincer-type ligand HN(SiMe 2 CH 2 PPh 2 ) 2 . 19 In a preliminary study we have prepared cationic seven-coordinate halo carbonyl molybdenum pincer complexes of the types [Mo(PNP- i Pr)(CO) 3 I] + and [Mo(PNP- i Pr)(CO) 2 (CH 3 CN)I] + . 13 Here we report on the synthesis, characterization, and reactivity of a series of new hydrido carbonyl molybdenum(II) and tungsten(II) PNP pincer complexes.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Hydrido Carbonyl Molybdenum and Tungsten PNP Pincer Complexes

Öztopçu¹,

Holzhacker²,

Puchberger³

et al. 2013

Organometallics

View full text Add to dashboard Cite

In the present study the Mo(0) and W(0) complexes [M(PNP)(CO)3] as well as seven-coordinate cationic hydridocarbonyl Mo(II) and W(II) complexes of the type [M(PNP)(CO)3H]+, featuring PNP pincer ligands based on 2,6-diaminopyridine, have been prepared and fully characterized. The synthesis of Mo(0) complexes [Mo(PNP)(CO)3] was accomplished by treatment of [Mo(CO)3(CH3CN)3] with the respective PNP ligands. The analogous W(0) complexes were prepared by reduction of the bromocarbonyl complexes [W(PNP)(CO)3Br]+ with NaHg. These intermediates were obtained from the known dinuclear complex [W(CO)4(μ-Br)Br]2, prepared in situ from W(CO)6 and stoichiometric amounts of Br2. Addition of HBF4 to [M(PNP)(CO)3] resulted in clean protonation at the molybdenum and tungsten centers to generate the Mo(II) and W(II) hydride complexes [M(PNP)(CO)3H]+. The protonation is fully reversible, and upon addition of NEt3 as base the Mo(0) and W(0) complexes [M(PNP)(CO)3] are regenerated quantitatively. All heptacoordinate complexes exhibit fluxional behavior in solution. The mechanism of the dynamic process of the hydrido carbonyl complexes was investigated by means of DFT calculations, revealing that it occurs in a single step. The structures of representative complexes were determined by X-ray single-crystal analyses.

show abstract

Synthesis and oxidation of d6 tungsten pincer complexes: a complete series of tungsten(ii) hydridocarbonyl and halocarbonyl pincer complexes

Cited by 17 publications

References 38 publications

Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes

Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes

A complete series of halocarbonyl molybdenum PNP pincer complexes – Unexpected differences between NH and NMe spacers

Synthesis and Characterization of Hydrido Carbonyl Molybdenum and Tungsten PNP Pincer Complexes

Contact Info

Product

Resources

About