Stereochemical control of iron(II) complexes containing a diphosphine ligand with a pendant nitrogen base

Renee M. Henry; Richard K. Shoemaker; Rachel H. Newell; George M. Jacobsen; Daniel L. DuBois; M. Rakowski DuBois

doi:10.1021/om050071c

Stereochemical control of iron(II) complexes containing a diphosphine ligand with a pendant nitrogen base

Renee M. Henry, Richard K. Shoemaker, Rachel H. Newell, George M. Jacobsen, Daniel L. DuBois, M. Rakowski DuBois

Pacific Northwest National Laboratory

Research output: Contribution to journal › Article

57 Citations (Scopus)

Abstract

A series of cis and trans Fe(II) complexes containing the diphosphine ligand PNP (where PNP is bis((diethylphosphino)methyl)methylamine) have been prepared and isolated. These include cis-[Fe(PNP) ₂(CH ₃CN) ₂](BF ₄) ₂ (3), cis-[Fe(PNP) ₂(CH ₃CN)(CO)](BF ₄) ₂ (4), trans-[Fe-(PNP)(dmpm)(CH ₃CN) ₂](BF ₄) ₂ (5), trans-Fe(PNP)(dmpm)Cl ₂ (6), trans-[Fe(PNP)(dmpm) (CO)-Cl] ₂[FeCl ₄] (7), trans-HFe(PNP)(dmpm)Cl (8), and trans-[HFe(PNP)(dmpm)(CH ₃CN)]BPh ₄ (9) (where dmpm is bis(dimethylphosphino)methane). In addition, the cations trans-[HFe-(PNP)(dmpm) (CO)] ⁺ (10) and trans-[(H ₂)Fe(PNP)(dmpm)(H)] ⁺ (11) have been observed in solution. These complexes all possess a pendant base that bridges the two phosphorus atoms of the PNP ligand. A cis geometry is observed for those complexes containing two PNP ligands, whereas a trans geometry is observed for the complexes containing one PNP ligand and one dmpm ligand. The molecular structures of cis-[Fe(PNP) ₂(CH ₃CN)(CO)](BPh ₄) ₂ and trans-[HFe(PNP)(dmpm) (CH ₃CN)]BPh ₄ have been confirmed by X-ray diffraction studies. Protonation of 5, 7, and 10 occurs at the nitrogen atom of the PNP ligand, and pK _a values are reported for the corresponding protonated complexes. The formation of the dihydrogen complex [trans-[(H ₂)Fe(PNP)(dmpm)(H)] ⁺ and the protonated PNHP complex trans-[HFe-(PNHP)(dmpm)(CO)] ²⁺ demonstrate that intramolecular heterolytic cleavage of the dihydrogen ligand can be controlled by varying the nature of the ligand trans to the incipient dihydrogen ligand.

Original language	English
Pages (from-to)	2481-2491
Number of pages	11
Journal	Organometallics
Volume	24
Issue number	10
DOIs	https://doi.org/10.1021/om050071c
Publication status	Published - May 9 2005

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ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

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Henry, R. M., Shoemaker, R. K., Newell, R. H., Jacobsen, G. M., DuBois, D. L., & DuBois, M. R. (2005). Stereochemical control of iron(II) complexes containing a diphosphine ligand with a pendant nitrogen base. Organometallics, 24(10), 2481-2491. https://doi.org/10.1021/om050071c

@article{1406e00e78f24655a11161f0735dabdc,

title = "Stereochemical control of iron(II) complexes containing a diphosphine ligand with a pendant nitrogen base",

abstract = "A series of cis and trans Fe(II) complexes containing the diphosphine ligand PNP (where PNP is bis((diethylphosphino)methyl)methylamine) have been prepared and isolated. These include cis-[Fe(PNP) 2(CH 3CN) 2](BF 4) 2 (3), cis-[Fe(PNP) 2(CH 3CN)(CO)](BF 4) 2 (4), trans-[Fe-(PNP)(dmpm)(CH 3CN) 2](BF 4) 2 (5), trans-Fe(PNP)(dmpm)Cl 2 (6), trans-[Fe(PNP)(dmpm) (CO)-Cl] 2[FeCl 4] (7), trans-HFe(PNP)(dmpm)Cl (8), and trans-[HFe(PNP)(dmpm)(CH 3CN)]BPh 4 (9) (where dmpm is bis(dimethylphosphino)methane). In addition, the cations trans-[HFe-(PNP)(dmpm) (CO)] + (10) and trans-[(H 2)Fe(PNP)(dmpm)(H)] + (11) have been observed in solution. These complexes all possess a pendant base that bridges the two phosphorus atoms of the PNP ligand. A cis geometry is observed for those complexes containing two PNP ligands, whereas a trans geometry is observed for the complexes containing one PNP ligand and one dmpm ligand. The molecular structures of cis-[Fe(PNP) 2(CH 3CN)(CO)](BPh 4) 2 and trans-[HFe(PNP)(dmpm) (CH 3CN)]BPh 4 have been confirmed by X-ray diffraction studies. Protonation of 5, 7, and 10 occurs at the nitrogen atom of the PNP ligand, and pK a values are reported for the corresponding protonated complexes. The formation of the dihydrogen complex [trans-[(H 2)Fe(PNP)(dmpm)(H)] + and the protonated PNHP complex trans-[HFe-(PNHP)(dmpm)(CO)] 2+ demonstrate that intramolecular heterolytic cleavage of the dihydrogen ligand can be controlled by varying the nature of the ligand trans to the incipient dihydrogen ligand.",

author = "Henry, {Renee M.} and Shoemaker, {Richard K.} and Newell, {Rachel H.} and Jacobsen, {George M.} and DuBois, {Daniel L.} and DuBois, {M. Rakowski}",

year = "2005",

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T1 - Stereochemical control of iron(II) complexes containing a diphosphine ligand with a pendant nitrogen base

AU - Henry, Renee M.

AU - Shoemaker, Richard K.

AU - Newell, Rachel H.

AU - Jacobsen, George M.

AU - DuBois, Daniel L.

AU - DuBois, M. Rakowski

PY - 2005/5/9

Y1 - 2005/5/9

N2 - A series of cis and trans Fe(II) complexes containing the diphosphine ligand PNP (where PNP is bis((diethylphosphino)methyl)methylamine) have been prepared and isolated. These include cis-[Fe(PNP) 2(CH 3CN) 2](BF 4) 2 (3), cis-[Fe(PNP) 2(CH 3CN)(CO)](BF 4) 2 (4), trans-[Fe-(PNP)(dmpm)(CH 3CN) 2](BF 4) 2 (5), trans-Fe(PNP)(dmpm)Cl 2 (6), trans-[Fe(PNP)(dmpm) (CO)-Cl] 2[FeCl 4] (7), trans-HFe(PNP)(dmpm)Cl (8), and trans-[HFe(PNP)(dmpm)(CH 3CN)]BPh 4 (9) (where dmpm is bis(dimethylphosphino)methane). In addition, the cations trans-[HFe-(PNP)(dmpm) (CO)] + (10) and trans-[(H 2)Fe(PNP)(dmpm)(H)] + (11) have been observed in solution. These complexes all possess a pendant base that bridges the two phosphorus atoms of the PNP ligand. A cis geometry is observed for those complexes containing two PNP ligands, whereas a trans geometry is observed for the complexes containing one PNP ligand and one dmpm ligand. The molecular structures of cis-[Fe(PNP) 2(CH 3CN)(CO)](BPh 4) 2 and trans-[HFe(PNP)(dmpm) (CH 3CN)]BPh 4 have been confirmed by X-ray diffraction studies. Protonation of 5, 7, and 10 occurs at the nitrogen atom of the PNP ligand, and pK a values are reported for the corresponding protonated complexes. The formation of the dihydrogen complex [trans-[(H 2)Fe(PNP)(dmpm)(H)] + and the protonated PNHP complex trans-[HFe-(PNHP)(dmpm)(CO)] 2+ demonstrate that intramolecular heterolytic cleavage of the dihydrogen ligand can be controlled by varying the nature of the ligand trans to the incipient dihydrogen ligand.

AB - A series of cis and trans Fe(II) complexes containing the diphosphine ligand PNP (where PNP is bis((diethylphosphino)methyl)methylamine) have been prepared and isolated. These include cis-[Fe(PNP) 2(CH 3CN) 2](BF 4) 2 (3), cis-[Fe(PNP) 2(CH 3CN)(CO)](BF 4) 2 (4), trans-[Fe-(PNP)(dmpm)(CH 3CN) 2](BF 4) 2 (5), trans-Fe(PNP)(dmpm)Cl 2 (6), trans-[Fe(PNP)(dmpm) (CO)-Cl] 2[FeCl 4] (7), trans-HFe(PNP)(dmpm)Cl (8), and trans-[HFe(PNP)(dmpm)(CH 3CN)]BPh 4 (9) (where dmpm is bis(dimethylphosphino)methane). In addition, the cations trans-[HFe-(PNP)(dmpm) (CO)] + (10) and trans-[(H 2)Fe(PNP)(dmpm)(H)] + (11) have been observed in solution. These complexes all possess a pendant base that bridges the two phosphorus atoms of the PNP ligand. A cis geometry is observed for those complexes containing two PNP ligands, whereas a trans geometry is observed for the complexes containing one PNP ligand and one dmpm ligand. The molecular structures of cis-[Fe(PNP) 2(CH 3CN)(CO)](BPh 4) 2 and trans-[HFe(PNP)(dmpm) (CH 3CN)]BPh 4 have been confirmed by X-ray diffraction studies. Protonation of 5, 7, and 10 occurs at the nitrogen atom of the PNP ligand, and pK a values are reported for the corresponding protonated complexes. The formation of the dihydrogen complex [trans-[(H 2)Fe(PNP)(dmpm)(H)] + and the protonated PNHP complex trans-[HFe-(PNHP)(dmpm)(CO)] 2+ demonstrate that intramolecular heterolytic cleavage of the dihydrogen ligand can be controlled by varying the nature of the ligand trans to the incipient dihydrogen ligand.

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