Synthesis, Structure, and Solution Dynamics of (η5-2,4-Dimethylpentadienyl)Co[P(C2H5)3]2 and (anti-η3-2,4-Dimethylpentadienyl)Co[P(CH3)3]3

John R. Bleeke; Wei Jun Peng

doi:10.1021/om00087a019

Synthesis, Structure, and Solution Dynamics of (η⁵-2,4-Dimethylpentadienyl)Co[P(C₂H₅)₃]₂ and (anti-η³-2,4-Dimethylpentadienyl)Co[P(CH₃)₃]₃

John R. Bleeke
, Wei Jun Peng

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

34 Scopus citations

Abstract

Reaction of CoCl₂ with P(C₂H₅)₃, potassium 2,4-dimethylpentadienide, and a reducing agent (zinc dust or additional potassium 2,4-dimethylpentadienide) results in the formation of (η⁵-2,4-dimethylpentadienyl) Co[P(C₂H₅)₃]₂,1. The crystal structure of 1 has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P2₁/c with a = 7.928 (2) Å, b = 18.041 (7) Å, c = 15.592 (4) Å, β = 92.81 (2)°, and Z = 4. The two P(C₂H₅)₃ ligands in 1 are oriented with one eclipsing the open edge and the other eclipsing the central carbon atom of the 2,4-dimethylpentadienyl ligand. The five cobalt-bound carbon atoms of the U-shaped 2,4-dimethylpentadienyl ligand are essentially coplanar. Reaction of ClCo[P(CH₃)₃]₃ with potassium 2,4-dimethylpentadienide produces (anti-η³-2,4-dimethylpentadienyl) Co[P(CH₃)₃]₃,2a. The crystal structure of 2a has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P2₁/c with a = 8.927 (2) Å,b = 15.008 (6) Å, c = 16.694 (4) Å,β = 104.33 (2)°, and Z = 4. The geometry about the cobalt atom approximates a square pyramid, with two of the allylic carbon atoms of the 2,4-dimethylpentadienyl ligand (C1 and C3) occupying adjacent basal sites, two of the P(CH₃)₃ phosphorus atoms (P1 and P2) occupying the remaining basal sites, and the final P(CH₃)₃ phosphorus atom (P3) residing in the axial site. The mouth of the allylic portion of the 2,4-dimethylpentadienyl ligand faces the axial P(CH₃)₃ ligand; as a result, the vinylic portion of the 2,4-dimethylpentadienyl ligand lies above the basal plane. The 2,4-dimethylpentadienyl ligand is U-shaped. However, it is not planar; the vinylic moiety is bent substantially out of the plane of the allylic moiety away from the cobalt atom. In solution, 2a equilibrates with its syn isomer, (syn-η³-2,4-dimethylpentadienyl) Co[P(CH₃)₃]₃, 2b, producing a 70:30 mixture of 2a-2b. Spin saturation transfer NMR experiments suggest that the mechanism for interconversion of 2a and 2b involves a C3-bound (η¹-2,4-dimethylpentadienyl) Co[P(CH₃)₃]₃ intermediate.

Original language	English
Pages (from-to)	1422-1426
Number of pages	5
Journal	Organometallics
Volume	3
Issue number	9
DOIs	https://doi.org/10.1021/om00087a019
State	Published - Mar 1984

Access to Document

10.1021/om00087a019

Cite this

@article{cfc2f6c2a004436ca9302f66462f4828,

title = "Synthesis, Structure, and Solution Dynamics of (η5-2,4-Dimethylpentadienyl)Co[P(C2H5)3]2 and (anti-η3-2,4-Dimethylpentadienyl)Co[P(CH3)3]3",

abstract = "Reaction of CoCl2 with P(C2H5)3, potassium 2,4-dimethylpentadienide, and a reducing agent (zinc dust or additional potassium 2,4-dimethylpentadienide) results in the formation of (η5-2,4-dimethylpentadienyl) Co[P(C2H5)3]2,1. The crystal structure of 1 has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 7.928 (2) {\AA}, b = 18.041 (7) {\AA}, c = 15.592 (4) {\AA}, β = 92.81 (2)°, and Z = 4. The two P(C2H5)3 ligands in 1 are oriented with one eclipsing the open edge and the other eclipsing the central carbon atom of the 2,4-dimethylpentadienyl ligand. The five cobalt-bound carbon atoms of the U-shaped 2,4-dimethylpentadienyl ligand are essentially coplanar. Reaction of ClCo[P(CH3)3]3 with potassium 2,4-dimethylpentadienide produces (anti-η3-2,4-dimethylpentadienyl) Co[P(CH3)3]3,2a. The crystal structure of 2a has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 8.927 (2) {\AA},b = 15.008 (6) {\AA}, c = 16.694 (4) {\AA},β = 104.33 (2)°, and Z = 4. The geometry about the cobalt atom approximates a square pyramid, with two of the allylic carbon atoms of the 2,4-dimethylpentadienyl ligand (C1 and C3) occupying adjacent basal sites, two of the P(CH3)3 phosphorus atoms (P1 and P2) occupying the remaining basal sites, and the final P(CH3)3 phosphorus atom (P3) residing in the axial site. The mouth of the allylic portion of the 2,4-dimethylpentadienyl ligand faces the axial P(CH3)3 ligand; as a result, the vinylic portion of the 2,4-dimethylpentadienyl ligand lies above the basal plane. The 2,4-dimethylpentadienyl ligand is U-shaped. However, it is not planar; the vinylic moiety is bent substantially out of the plane of the allylic moiety away from the cobalt atom. In solution, 2a equilibrates with its syn isomer, (syn-η3-2,4-dimethylpentadienyl) Co[P(CH3)3]3, 2b, producing a 70:30 mixture of 2a-2b. Spin saturation transfer NMR experiments suggest that the mechanism for interconversion of 2a and 2b involves a C3-bound (η1-2,4-dimethylpentadienyl) Co[P(CH3)3]3 intermediate.",

author = "Bleeke, \{John R.\} and Peng, \{Wei Jun\}",

year = "1984",

month = mar,

doi = "10.1021/om00087a019",

language = "English",

volume = "3",

pages = "1422--1426",

journal = "Organometallics",

issn = "0276-7333",

number = "9",

}

TY - JOUR

T1 - Synthesis, Structure, and Solution Dynamics of (η5-2,4-Dimethylpentadienyl)Co[P(C2H5)3]2 and (anti-η3-2,4-Dimethylpentadienyl)Co[P(CH3)3]3

AU - Bleeke, John R.

AU - Peng, Wei Jun

PY - 1984/3

Y1 - 1984/3

N2 - Reaction of CoCl2 with P(C2H5)3, potassium 2,4-dimethylpentadienide, and a reducing agent (zinc dust or additional potassium 2,4-dimethylpentadienide) results in the formation of (η5-2,4-dimethylpentadienyl) Co[P(C2H5)3]2,1. The crystal structure of 1 has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 7.928 (2) Å, b = 18.041 (7) Å, c = 15.592 (4) Å, β = 92.81 (2)°, and Z = 4. The two P(C2H5)3 ligands in 1 are oriented with one eclipsing the open edge and the other eclipsing the central carbon atom of the 2,4-dimethylpentadienyl ligand. The five cobalt-bound carbon atoms of the U-shaped 2,4-dimethylpentadienyl ligand are essentially coplanar. Reaction of ClCo[P(CH3)3]3 with potassium 2,4-dimethylpentadienide produces (anti-η3-2,4-dimethylpentadienyl) Co[P(CH3)3]3,2a. The crystal structure of 2a has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 8.927 (2) Å,b = 15.008 (6) Å, c = 16.694 (4) Å,β = 104.33 (2)°, and Z = 4. The geometry about the cobalt atom approximates a square pyramid, with two of the allylic carbon atoms of the 2,4-dimethylpentadienyl ligand (C1 and C3) occupying adjacent basal sites, two of the P(CH3)3 phosphorus atoms (P1 and P2) occupying the remaining basal sites, and the final P(CH3)3 phosphorus atom (P3) residing in the axial site. The mouth of the allylic portion of the 2,4-dimethylpentadienyl ligand faces the axial P(CH3)3 ligand; as a result, the vinylic portion of the 2,4-dimethylpentadienyl ligand lies above the basal plane. The 2,4-dimethylpentadienyl ligand is U-shaped. However, it is not planar; the vinylic moiety is bent substantially out of the plane of the allylic moiety away from the cobalt atom. In solution, 2a equilibrates with its syn isomer, (syn-η3-2,4-dimethylpentadienyl) Co[P(CH3)3]3, 2b, producing a 70:30 mixture of 2a-2b. Spin saturation transfer NMR experiments suggest that the mechanism for interconversion of 2a and 2b involves a C3-bound (η1-2,4-dimethylpentadienyl) Co[P(CH3)3]3 intermediate.

AB - Reaction of CoCl2 with P(C2H5)3, potassium 2,4-dimethylpentadienide, and a reducing agent (zinc dust or additional potassium 2,4-dimethylpentadienide) results in the formation of (η5-2,4-dimethylpentadienyl) Co[P(C2H5)3]2,1. The crystal structure of 1 has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 7.928 (2) Å, b = 18.041 (7) Å, c = 15.592 (4) Å, β = 92.81 (2)°, and Z = 4. The two P(C2H5)3 ligands in 1 are oriented with one eclipsing the open edge and the other eclipsing the central carbon atom of the 2,4-dimethylpentadienyl ligand. The five cobalt-bound carbon atoms of the U-shaped 2,4-dimethylpentadienyl ligand are essentially coplanar. Reaction of ClCo[P(CH3)3]3 with potassium 2,4-dimethylpentadienide produces (anti-η3-2,4-dimethylpentadienyl) Co[P(CH3)3]3,2a. The crystal structure of 2a has been determined by X-ray diffraction. The complex crystallizes in the monoclinic space group P21/c with a = 8.927 (2) Å,b = 15.008 (6) Å, c = 16.694 (4) Å,β = 104.33 (2)°, and Z = 4. The geometry about the cobalt atom approximates a square pyramid, with two of the allylic carbon atoms of the 2,4-dimethylpentadienyl ligand (C1 and C3) occupying adjacent basal sites, two of the P(CH3)3 phosphorus atoms (P1 and P2) occupying the remaining basal sites, and the final P(CH3)3 phosphorus atom (P3) residing in the axial site. The mouth of the allylic portion of the 2,4-dimethylpentadienyl ligand faces the axial P(CH3)3 ligand; as a result, the vinylic portion of the 2,4-dimethylpentadienyl ligand lies above the basal plane. The 2,4-dimethylpentadienyl ligand is U-shaped. However, it is not planar; the vinylic moiety is bent substantially out of the plane of the allylic moiety away from the cobalt atom. In solution, 2a equilibrates with its syn isomer, (syn-η3-2,4-dimethylpentadienyl) Co[P(CH3)3]3, 2b, producing a 70:30 mixture of 2a-2b. Spin saturation transfer NMR experiments suggest that the mechanism for interconversion of 2a and 2b involves a C3-bound (η1-2,4-dimethylpentadienyl) Co[P(CH3)3]3 intermediate.

UR - https://www.scopus.com/pages/publications/0038625578

U2 - 10.1021/om00087a019

DO - 10.1021/om00087a019

M3 - Article

AN - SCOPUS:0038625578

SN - 0276-7333

VL - 3

SP - 1422

EP - 1426

JO - Organometallics

JF - Organometallics

IS - 9

ER -

Synthesis, Structure, and Solution Dynamics of (η⁵-2,4-Dimethylpentadienyl)Co[P(C₂H₅)₃]₂ and (anti-η³-2,4-Dimethylpentadienyl)Co[P(CH₃)₃]₃

Abstract

Access to Document

Other files and links

Fingerprint

Cite this