[2,2-Di(2-pyridyl)-1,3-dioxolane-N,N']dichloropalladium(II), [PdCl2(C13H12N2O2)]

Newkome, George R.; Gupta, Vinod K.; Theriot, Kevin J.; Ewing, James C.; Wicelinski, S.P.; Huie, W. R.; Fronczek, Frank R.; Watkins, Steven F.

doi:10.1107/s0108270184007939

Cited by 7 publications

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“…The structures of the dichloride complexes 4i , n , o , q were determined by X-ray diffraction and are shown in Figures – . These structures are similar to those of other {bis(heterocycle)methane)}Pd II complexes. – In all four complexes, the geometry at Pd is square planar, the (N ∧ N)Pd ring has a boat conformation, and the −CHAr 2 substituent on the bridging methylene carbon is in the axial position. The degree of (N ∧ N)Pd ring boating can be assessed by the angles between the N−C−C−N and N−Pd−N planes, the N−C−C−N and C−C br −C planes, and the two heterocycle ring planes.…”

Section: Resultssupporting

confidence: 68%

Ethylene Polymerization by Sterically Crowded Palladium(II) Complexes that Contain Bis(heterocycle)methane Ligands

Burns

Jordan

2007

Organometallics

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The catalytic ethylene polymerization reactions of (N∧N)PdMe(L)+ species that contain bulky bis(heterocycle)methane ligands were studied (N∧N = (1-Me-imidazol-2-yl)2CHCH(p-tolyl)2 (1i), (1-Me-imidazol-2-yl)2CHC(p-tolyl)3 (1j), (5-Me-pyridin-2-yl)2CHC(p-tolyl)2)3 (1k), (5-Me-pyridin-2-yl)2CHCH(p-tolyl)2 (1l), (3-Me-pyridin-2-yl)2CHCH(p-tolyl)2 (1m), (5-Me-pyridin-2-yl)2CHCH(m-xylyl)2 (1n), (3-Me-pyridin-2-yl)2CHCH(m-xylyl)2 (1o), (quinol-2-yl)2CHCH(m-xylyl)2 (1p), and (3-Me-quinol-2-yl)2CHCH(m-xylyl)2 (1q). (N∧N)PdMe2 (2i,j,q) and (N∧N)Pd(Me)Cl (3m−o) complexes were converted to (N∧N)Pd{C(O)Me}CO+ complexes (7i,j,m−o,q). The νCO values for 7i,j,m−o,q show that there is weak back-bonding in these species. Complexes 2i,j and (N∧N)Pd(Me)Cl complexes 3l−o were converted to (N∧N)Pd(Me)(H2CCH2)+ (8i,j,l−o and 8q (not directly observed)). First-order rate constants for ethylene insertion of 8i,j,l−o were determined by NMR. Increasing the electrophilic character and the steric bulk of the (N∧N)Pd unit increases the rate of ethylene insertion. In-situ-generated 8j,l−n,q produce low molecular weight polyethylene (M w ≤ 4200), while 8o produces higher molecular weight polyethylene (M w = 34 000). Polyethylene produced by 8j,l,m contains 100 branches/103 C, while that from 8n,o,q contains 60 branches/103C.

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Section: Resultssupporting

confidence: 68%

Ethylene Polymerization by Sterically Crowded Palladium(II) Complexes that Contain Bis(heterocycle)methane Ligands

Burns

Jordan

2007

Organometallics

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“…Complexes 2a,b,d,e and 3f likely have boat conformations, as shown for 2e in Scheme 3, similar to those observed for the analogous complexes {1,3dioxolane)C(py) 2 }PdCl 2 , {Me 2 C(pz) 2 }PdCl 2 , {Ph 2 C(pz) 2 }PdCl 2 , and {(n-hexyl)HC(mim) 2 }PdCl 2 . 7,15,[23][24][25] Previously, Canty observed a singlet for the methylene bridge hydrogens in the 1 H NMR spectrum of 2a down to -70 °C, consistent with rapid inversion of the (N ∧ N)Pd chelate ring. 8 In contrast, slower ring inversion is observed for 2d,e, and 3f.…”

Section: Resultsmentioning

confidence: 95%

Ethylene Dimerization by Cationic Palladium(II) Alkyl Complexes that Contain Bis(heterocycle)methane Ligands

Burns

Jordan

2007

Organometallics

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The catalytic ethylene dimerization reactions of (N∧N)PdMe(L)+ species that contain bidentate nitrogen donor ligands were studied (N∧N = (1-Me-imidazol-2-yl)2CH2 (a); (1-Me-imidazol-2-yl)2CH(C6H13) (b), 1,1′-di(triphenylmethyl)-4,4′-biimidazole (c), (5-Me-pyridin-2-yl)2CH2 (d), (pyrazol-1-yl)2CH2 (e), (3,5-Me2-pyrazol-1-yl)2CH2 (f), (4-Me-C6H4)NCMeCMeN(4-Me-C6H4) (g), and (2,6-iPr2-C6H3)NCMeCMeN(2,6-iPr2-C6H3) (h)). (N∧N)PdMe2 (2a–e,g) and (N∧N)Pd(Me)Cl (3f–h) complexes were converted to [(N∧N)Pd{C(O)Me}CO][B(C6F5)4)] (7a,c–h), [(N∧N)Pd(Me)(H2CCH2)][B(C6F5)4)] (8a−g), and [(N∧N)Pd(Me)(H2CCH2)][SbF6] (8f′). The νCO values for 7a,c−f show that there is weak back-bonding in these species, the donor ability of the N∧N ligand varies in the order imidazole > pyridine > pyrazole, and variation of the chelate ring size does not strongly affect the electron density at Pd. 8a,c−g and 8f′ dimerize ethylene by an insertion/β-H elimination mechanism. The catalyst resting state is (N∧N)Pd(Et)(H2CCH2)+ (9a,c−g). First-order rate constants for ethylene insertion of 8a−g and 8f′ (k insert,Me) and 9a,c−g (k insert,Et) were determined by NMR. The k insert,Me and k insert,Et values for analogous (N∧N)Pd(R)(H2CCH2)+ species are similar. Increasing the electrophilic character and the steric bulk of the (N∧N)Pd unit leads to moderate increases in ethylene insertion rates.

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Polymer-supported 2,2′-dipyridylmethane: catalytic activity of transition metal complexes in hydrogenations and oligomerizations

Moberg

Rákos

1987

Journal of Organometallic Chemistry

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[2,2-Di(2-pyridyl)-1,3-dioxolane-N,N']dichloropalladium(II), [PdCl2(C13H12N2O2)]

Cited by 7 publications

References 0 publications

Ethylene Polymerization by Sterically Crowded Palladium(II) Complexes that Contain Bis(heterocycle)methane Ligands

Ethylene Polymerization by Sterically Crowded Palladium(II) Complexes that Contain Bis(heterocycle)methane Ligands

Ethylene Dimerization by Cationic Palladium(II) Alkyl Complexes that Contain Bis(heterocycle)methane Ligands

Polymer-supported 2,2′-dipyridylmethane: catalytic activity of transition metal complexes in hydrogenations and oligomerizations

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