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Ab initio Calculations of the Nuclear Quadrupole Coupling Constants of BHn

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Ab initio Calculations of the Nuclear Quadrupole Coupling Constants of BH

n = 2, 4

X

+

(X = NH

3

, PH

3

, H

2

O, H

2

S)

Tayyebe Partovi, Marjan A. Rafieea, and Nasser L. Hadipoura Department of Chemistry, Payame Noor University, Tehran, Iran

aDepartment of Chemistry, Tarbiat Modarres University, P.O. Box: 14115-175, Tehran, Iran Reprint requests to M. A. R.; E-mail: rafiee marjan@yahoo.com

Z. Naturforsch. 60a, 37 – 40 (2005); received July 31, 2004

The electronic structure and strength of acid-base bonding in the protonated boron-Lewis com- plexes BHn=2,4X+(X = NH3, PH3, H2O, H2S) and their neutral parents were studied. The results showed that in the H2BX+monocations the electron releasing from the donor atom in X to BH3is significant and more complete than in the other studied complexes. Therefore the bonding between the donor and acceptor in H2BX+is strongest. To obtain these data, the electric field gradient (EFG) at the quadrupolar nuclei in each complex was calculated. The EFG’s of the boron atom and other quadrupolar nuclei were calculated by the Gaussian 98 program, using the MP2/6-31G** method.

Key words: Ab initio Calculations; Acid-Base Lewis; Boron; EFG; NQR.

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