Multinuclear NMR Spectroscopic and X-ray Crystallographic Studies of Electronic and Steric Effects of Phosphonous Acid Ligands and Their Chlorophosphite Ligand Precursors in Tungsten Pentacarb­onyl Complexes

2013 ◽  
Vol 2013 (16) ◽  
pp. 2900-2911 ◽  
Author(s):  
Samantha D. Hastings ◽  
Houston Byrd ◽  
Leanne N. Gray ◽  
Michael J. Jablonsky ◽  
Jason L. Freeman ◽  
...  
Keyword(s):  
Steric Effects ◽  
Phosphonous Acid ◽  
X Ray ◽  
Multinuclear Nmr ◽  
Ligand Precursors ◽  
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.

Configuration on the C=N double bond of monosubstituted amidines and amidoximes

1989 ◽  
Vol 54 (12) ◽  
pp. 3245-3252 ◽  
Author(s):  
Bernard Tinant ◽  
Janine Dupont-Fenfau ◽  
Jean-Paul Declercq ◽  
Jaroslav Podlaha ◽  
Otto Exner
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Steric Effects ◽  
Model Compounds ◽  
X Ray ◽  
Analogous Model

Configuration on the C=N double bond of amidines and amidoximes is controlled by steric effects on the second nitrogen atom but there is a difference in the case of N’-monosubstituted derivatives: amidines prefer E configuration (conformation around the C-N bond sp) and amidoximes Z configuration (conformation ap). This was confirmed by the X-ray structures of two analogous model compounds N,N’-dimethyl-4-nitrobenzamidine (monoclinic, P21c, a = 10.855(3), b = 11.043(3), c = 8.593(3) Å, β = 105.69(2)°, V = 991.8(5) Å3, Z = 4, Dx = 1.29 g cm-3, CuKα, λ = 1.5418 Å, μ = 7.91 cm-1, F(000) = 408, T = 291 K, R = 0.065 for 1 265 observed reflections) and N’-methyl-4-nitrobenzamidoxime (monoclinic, P21/a, a = 6.699(2), b = 24.178(9), c = 6.075(2) Å, β = 106.20(3)°, V = 944.9(6) Å3, Z = 4, Dx = 1.37 g cm-3, CuKα, λ = 1.5418 Å, μ =9.22 cm-1, F(000) = 408, T = 291 K, R = 0.079 for 1 278 observed reflections).

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
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