Electronic and Steric Effects on the Reductive Elimination of Diaryl Ethers from Palladium(II)

2003 ◽  
Vol 22 (13) ◽  
pp. 2775-2789 ◽  
Author(s):  
Grace Mann ◽  
Quinetta Shelby ◽  
Amy H. Roy ◽  
John F. Hartwig
Keyword(s):  
Reductive Elimination ◽  
Steric Effects ◽  
Diaryl Ethers ◽  
Electronic And Steric Effects

Oxidative addition of monosilanes to planar iridium(I) complexes and carbonylation of the resulting adducts

1977 ◽  
Vol 30 (6) ◽  
pp. 1201 ◽  
Author(s):  
MA Bennett ◽  
R Charles ◽  
PJ Fraser
Keyword(s):  
Carbon Monoxide ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Steric Effects ◽  
Ambient Conditions ◽  
Tetragonal Pyramidal ◽  
Group 5 ◽  
Electronic And Steric Effects

Silanes [R3SiH; R3 = Cl3, MeCl2, (EtO)3, Ph3] undergo irreversible oxidative addition to planar iridium(I) complexes IrClL3 (L = PPh3, PMePh2 or AsPh3) to give silyliridium(III) hydrides IrHCl(SiR3)Ln (n = 2 or 3). The yellow, five-coordinate, probably tetragonal pyramidal complexes(n = 2) are formed mainly when L = PPh3 or AsPh3, and also in the case of L = PmePh2, R = Ph, whereas the colourless, six-coordinate, presumably octahedral adducts are formed predominantly when L = PMePh2. Both five- and six-coordinate adducts can be isolated from the addition of dichloro(methyl)silane to IrCl(AsPh3)3. Most of the adducts react with carbon monoxide under ambient conditions to give silyliridium(III) hydrido carbonyls, IrHCl(SiR3)(CO)L2, which may undergo partial or complete reductive elimination to IrCl(CO)L2 and R3SiH; the ease with which this occurs depends on L (PPh3 > PMePh2 > AsPh3) and on R3 [Ph3 > (EtO)3 > Cl3 ≈ MeCl2]. The reactions of silanes with IrClL3, RhClL3 and IrCl(CO)(PPh3)2 are compared, and the trends observed in the case of IrClL3 are discussed in terms of electronic and steric effects in the silyl and Group 5 donors. Structural assignments for the new complexes are based on i.r., far-i.r. and 1H N.M.R. data.

Electronic and steric effects on the intramolecular Schmidt reaction of alkyl azides with secondary benzyl alcohols

Tetrahedron ◽  
2014 ◽  
Vol 70 (3) ◽  
pp. 643-649 ◽  
Author(s):  
Xiaowei Sun ◽  
Chengzhe Gao ◽  
Fan Zhang ◽  
Zhuang Song ◽  
Lingyi Kong ◽  
...  
Keyword(s):  
Steric Effects ◽  
Schmidt Reaction ◽  
Benzyl Alcohols ◽  
Alkyl Azides ◽  
Electronic And Steric Effects

The Reactions of Substituted Germyl- and Silylhydrazines with BX3 and CY2 Acceptor Species

1972 ◽  
Vol 50 (4) ◽  
pp. 562-566 ◽  
Author(s):  
L. K. Peterson ◽  
K. I. Thé
Keyword(s):  
Molecular Weight ◽  
Nitrogen Atom ◽  
Low Temperatures ◽  
Adduct Formation ◽  
Steric Effects ◽  
Reaction Products ◽  
Hydrazine Derivatives ◽  
Basic Catalysts ◽  
Series Of Experiments ◽  
Electronic And Steric Effects

Boron trimethyl reacts with each of the organometalloid-hydrazine derivatives Me2NN(R)GeMe3 (R = H, Me, SiMe3) except Me2NN(SiMe3)GeMe3, and with Me2NNHSiMe3, forming 1:1 adducts. With Me2NN(SiMe3)GeMe3 and BMe3, no adduct was formed even at low temperatures. On the basis of p.m.r. spectra, the metalloid-substituted nitrogen atom rather than the terminal nitrogen, is indicated as the basic center at which adduct formation occurs. With BF3, the Si—N and Ge—N bonds of the hydrazine derivatives were cleaved, again indicating attack at the central nitrogen atom. In a series of experiments involving CY2 (Y = O, S) and Me2NN(R)MMe3 (R = H, Me, SiMe3; M = Si, Ge), reaction occurred readily for R = H, but less readily for R = Me and for the compound Me2NN(GeMe3)2, while no reaction was observed for the compounds Me2NN(SiMe3)2 and Me2NN(SiMe3)GeMe3, even when heat or basic catalysts were employed. Reaction products, carbamate and thiocarbamate derivatives, Me2NN(R)C(Y)YMMe3, were characterized on the basis molecular weight, i.r., p.m.r., and mass spectroscopy, and m.p. data. Ease of formation is discussed in terms of electronic and steric effects.

Highly Stereo- and Regioselective Allylations Catalyzed by Mo−Pyridylamide Complexes:  Electronic and Steric Effects of the Ligand

2000 ◽  
Vol 65 (18) ◽  
pp. 5868-5870 ◽  
Author(s):  
Oscar Belda ◽  
Nils-Fredrik Kaiser ◽  
Ulf Bremberg ◽  
Mats Larhed ◽  
Anders Hallberg ◽  
...  
Keyword(s):  
Steric Effects ◽  
Electronic And Steric Effects

Study of naphthopyran derivatives: structure and photochromic properties in solution and in polymer film

2021 ◽  
Vol 77 (7) ◽  
Author(s):  
Linqi Shi ◽  
Zipei Sun ◽  
Jiajie Tian ◽  
Yaodong Huang ◽  
Jiben Meng
Keyword(s):  
Uv Light ◽  
Steric Effects ◽  
Pmma Film ◽  
Structure Property ◽  
Photochromic Properties ◽  
X Ray ◽  
Structure Property Relationships ◽  
Substituent Group ◽  
Uv Light Irradiation ◽  
Electronic And Steric Effects

Four naphthopyran derivatives, namely, 3,3-bis(naphthalen-1-yl)-3H-naphtho[2,1-b]pyran, C33H22O, NP1, 3,3-bis([1,1′-biphenyl]-4-yl)-3H-naphtho[2,1-b]pyran, C37H26O, NP2, 3,3-bis(4-phenoxyphenyl)-3H-naphtho[2,1-b]pyran, C37H26O2, NP3, and 3,3-bis(4-methoxy-2-methylphenyl)-3H-naphtho[2,1-b]pyran, C29H26O3, NP4, were synthesized and their photochromic properties investigated. NP1–NP4 exhibited good photochromism in different solutions and in poly(methyl methacrylate) (PMMA) film under UV light irradiation. Solvatochromism and the electronic and steric effects of the substituent group on photochromism were analyzed and decolouration curves were found to fit a monoexponential kinetic decay in most cases. Single-crystal X-ray analysis of NP1 and NP2 revealed the structure–property relationships. Good fatigue resistance of NP1, both in solution and in the PMMA film, endows it with potential value for applications.

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