个人简介

Ph.D., 1992, University of Southern California M.S., 1989, University of Massachusetts at Dartmouth B.Sc. (Honours), 1983, M.Sc., 1985, University of Dhaka, Bangladesh

研究领域

Organic and Computational Chemistry

Our research interests involve the combined application of theory and experiment in structural-mechanistic studies. Our research work is centered on the generation and investigation of electron deficient carbocations by NMR spectroscopy, ab initio, DFT, IGLO and GIAO calculations. This include the structures of some of the most important carbocation intermediates, effects of heteroatoms on the stability of carbocations and their role in the electrophilic substitution reactions. Our work is also concerned with the possible role of onium dications (superelectrophiles) in superacid catalyzed reactions. Some electrophiles, such as carboxonium ions, nitronium ion and related systems are capable of further interaction with Bronsted or Lewis superacids can be greatly activated in superacidic systems. Such further interactions produce superelectrophiles, which are highly reactive, energetic, high lying intermediates of dipositive nature. They are the de facto reactive intermediates (such as NO2H2+, CH3COH2+ etc.) of many electrophilic reactions in superacidic systems. We also engaged in the computational study of the higher coordinate main group hydriodo cations. Such studies are very useful to identify new and exciting hypercoordinate carbonium (such as CH73+), boronium, alonium, sulfonium and ammonium ions. The real significance of these ions is that they led to the realization of electrophilic substitution and related transformations of saturated hydrocarbons (alkanes) and in general of electrophilic activation of C-H and C-C single bonds. CH5+ is considered the parent of nonclassical carbocations containing a five coordinate carbon atom. The cation preferred a Cs symmetrical structure with a two-electron three-center (2e-3c) bond as originally suggested by Olah et al in 1969. Olah also showed that the parent six coordinate carbocation, diprotonated methane (CH62+), has two 2e-3c bonding interactions in its minimum-energy structure. We later showed that even the parent seven coordinate carbocation, triprotonated methane (CH73+) is an energy minimum and has three 2e-3c bonding interactions in its minimum-energy structure. These results indicate the general importance of 3c-2e interactions in protonated alkanes. Schmidbaur and his associates have prepared a variety of highly interesting higher coordinate boron, carbon, nitrogen, oxygen, phosphorus and sulfur gold complexes and determined their X-ray structures.

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Olah, G. A.; Prakash, G. K. S.; Rasul, G., Protonated tert-Pentyl Dication (C5H122+, Isopentane Dication)" Dalton Trans., 2008, 521. Reddy, V. P; Rasul, G.; Prakash, G. K. S.; Olah, G. A.; "Structural Studies of Nonclassical Cyclobutylmethyl Cations by the ab initio Method" J. Org. Chem., 2007, 72, 3076 Rasul, G.; Prakash, G. K. S., Olah, G. A., "Comparative Study of the Hypercoordinate ions C7H9+ and C8H9+ by the Ab Initio/GIAO-CCSD(T) Method" J. Phys. Chem. A, 2006, 110, 11320 Rasul, G.; Olah, G. A., Prakash, G. K. S., "Ab Initio/GIAO-CCSD(T) Study of Bicyclic and Related Strained Olefins. Structures and 13C NMR Chemical Shifts", J. Phys. Chem. A, 2006, 110, 7197 Rasul, G.; Prakash, G. K. S., Olah, G. A., "Ab Initio/GIAO-CCSD(T) Study of Propenoyl (H2C=CH-CO+) and Isopentenoyl ((CH3)2C=CH-CO+) Cations and their Superelectrophilic Protonated Dications", J. Phys. Chem. A, 2006, 110, 1042 Rasul, G.; Prakash, G. K. S.; Olah, G. A.; "DFT Investigation of Tri(amino)amine N(NH2)32+ and Tri(azido)amine N(N3)32+ Dications and Related Mixed Amino(azido)ammonium Ions (N3)xN(NH2)4-x+ (x= 0 - 4) " Inorg. Chem., 2002, 41, 5589. Olah, G. A.; Prakash, G. K. S.; Rasul, G.; "Ab Initio Study of the Structures and Stabilities of the Dimer of Ethyl Cation, (C2H5+)2 and Related C4H102+ Isomers" J. Org. Chem., 2001, 66, 9011. Olah, G. A.; Prakash, G. K. S.; Rasul, G.; "Gitonic and Distonic Alkanonium Dications (Diprotonated Alkane Dications CnH2n+42+, n = 1 - 4)" J. Org. Chem., 2001, 66, 2907.