Open Access13 C nuclear magnetic resonance study of five- and six-coordinated carbon in nonclassical organometallic compounds: Dimeric trialkyl-, tricyclopropyl-, and triarylaluminums and some nido and closo carboranes
Author(s) -
George A. Oláh,
G. K. Surya Prakash,
Gao Liang,
Kenneth L. Henold,
Gary B. Haigh
Publication year - 1977
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.74.12.5217
Subject(s) - chemical shift , chemistry , coupling constant , crystallography , carbon 13 , group 2 organometallic chemistry , electron paramagnetic resonance , carbon atom , resonance (particle physics) , molecule , nuclear magnetic resonance , stereochemistry , organic chemistry , ring (chemistry) , atomic physics , physics , particle physics , quantum mechanics
A13 C nuclear magnetic resonance spectroscopic study of dimeric trimethyl-, triethyl-, tricyclopropyl-, and triarylaluminums is reported. The five-coordinated bridging carbons are found consistently more shielded than the terminal carbons, in accordance with the increased p-character of the former. The nature of bridging two-electron three-centered Al—C—Al bonds is discussed.13 C nuclear magnetic resonance shifts of severalnido andcloso carboranes containing five and six coordinated carbons and their13 C-1 H spin-spin coupling constants were also obtained. The relationship between the carbon chemical shifts and coordination number of the carbon atom is discussed. There is approximately a 20- to 40-ppm shielding of the13 C chemical shifts of five- and six-coordinated carbons, compared with those of four valent carbons, with a simultaneous generalincrease of JC-H coupling constants.