Infrared and Raman spectroscopy of carbohydrates. Paper V. Normal coordinate analysis of cellulose I

1975 ◽  
Vol 62 (3) ◽  
pp. 1145-1153 ◽  
Author(s):  
J. J. Cael ◽  
K. H. Gardner ◽  
J. L. Koenig ◽  
J. Blackwell
Keyword(s):  
Raman Spectroscopy ◽  
Normal Coordinate Analysis ◽  
Cellulose I ◽  
Normal Coordinate ◽  
Infrared And Raman Spectroscopy

Common Oxygen Binding Site in Hemocyanins from Arthropods and Mollusks. Evidence from Raman Spectroscopy and Normal Coordinate Analysis

1994 ◽  
Vol 116 (17) ◽  
pp. 7682-7691 ◽  
Author(s):  
Jinshu Ling ◽  
Lisa P. Nestor ◽  
Roman S. Czernuszewicz ◽  
Thomas G. Spiro ◽  
Robert Fraczkiewicz ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Binding Site ◽  
Normal Coordinate Analysis ◽  
Oxygen Binding ◽  
Normal Coordinate

Vibrational Spectra, Vibrational Analysis and Stereochemistries of the Pentacoordinate Molecules SiCl3X•N(CH3)3 and SiCl3X•N(CD3)3 where X = H, F, Br, or I

1973 ◽  
Vol 51 (4) ◽  
pp. 609-617 ◽  
Author(s):  
D. Boal ◽  
G. A. Ozin
Keyword(s):  
Raman Spectroscopy ◽  
Vibrational Spectra ◽  
Vibrational Analysis ◽  
Axial Position ◽  
Normal Coordinate ◽  
Trigonal Bipyramidal ◽  
Factors Influencing ◽  
Infrared And Raman Spectroscopy

The thermally unstable compounds SiCl3X•N(CH3)3 and SiCl3X•N(CD3)3 where X = H, F, Br, or I are studied at −196 °C by infrared and Raman spectroscopy. The data are compatible with molecular five coordinate compounds having a trigonal bipyramidal stereochemistry with the ligand trimethylamine always in the axial position. Using the vibrational data and normal coordinate analyses in both the Cs and C3v configurations, X is suggested to be equatorial for H and F and axial for Br and I. The factors influencing the position of X in the compounds are discussed.

Bonding, activation, and protonation of dinitrogen on a molybdenum pentaphosphine complex — Comparison to trans-bis(dinitrogen) and -nitrile – dinitrogen complexes with tetraphosphine coordination

2005 ◽  
Vol 83 (4) ◽  
pp. 385-402 ◽  
Author(s):  
Gerald C Stephan ◽  
Gerhard Peters ◽  
Nicolai Lehnert ◽  
Carsten M Habeck ◽  
Christian Näther ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Nitrogen Fixation ◽  
Analysis Procedure ◽  
Normal Coordinate Analysis ◽  
Triflic Acid ◽  
Normal Coordinate ◽  
Phosphine Complexes ◽  
Dinitrogen Complexes ◽  
Donor Acceptor ◽  
Ir And Raman

The molybdenum-N2 pentaphosphine complex [Mo(N2)(dpepp)(dppm)] (1) containing a bi- and a tridentate phosphine ligand (dpepp = PhP(CH2CH2PPh2)2, dppm = Ph2PCH2PPh2) has been prepared and characterized. By protonation of 1 with triflic acid the NNH2 complex [Mo(NNH2)(dpepp)(dppm)](CF3SO3)2 (2) is formed without loss of the pentaphosphine coordination. The electronic properties of 1 and 2 and their 15N and (or) 2H counterparts are investigated by NMR, IR, and Raman spectroscopy coupled to DFT frequency and NMR shift calculations. Force constants are evaluated from experimental frequencies and isotope shifts by the quantum chemistry based normal coordinate analysis procedure (QCB-NCA). The results for the N2 complex 1 are compared with those obtained earlier for bis(dinitrogen) and trans-nitrile dinitrogen systems. Importantly, the N2 in the pentaphosphine complex is more strongly activated compared to corresponding bis(dinitrogen) compounds and more weakly activated compared to trans-nitrile N2 systems. The activation of the NNH2 ligand in complex 2 is similar to trans-nitrile systems and weaker compared to corresponding NNH2 complexes with coordinated anions like [MoF(NNH2)(dppe)2](BF4). These results are discussed based on the relative donor–acceptor properties of the respective trans ligands, demonstrating the influence of σ donation and π acceptance on the activation of N2 in transition metal complexes.Key words: nitrogen fixation, phosphine complexes, NMR shifts, DFT calculations, normal coordinate analysis.

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