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Addition of Carbenes to the Sidewalls of Single‐Walled Carbon Nanotubes
Author(s) -
Bettinger Holger F.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200501217
Subject(s) - zigzag , materials science , carbon nanotube , cyclopropane , density functional theory , crystallography , exothermic reaction , fullerene , triple bond , hydrogen bond , cluster (spacecraft) , computational chemistry , nanotechnology , double bond , chemistry , organic chemistry , polymer chemistry , molecule , geometry , ring (chemistry) , mathematics , computer science , programming language
The addition of carbenes CX 2 (X=H, Cl) to single‐walled carbon nanotubes (SWNTs) was investigated by density functional theory and finite, hydrogen‐terminated nanotube clusters or periodic boundary conditions in conjunction with basis sets of up to polarized triple‐ ζ quality. For armchair [(3,3) to (12,12)] and zigzag tubes [(3,0) to (18,0)], reaction of CH 2 with the CC bond oriented along the tube axis ( A ) is less exothermic than with those CC bonds having circumferential ( C ) orientation. This preference decreases monotonically with increasing tube diameter for armchair, but not for zigzag tubes; here, tubes with small band gaps have a very low preference for circumferential addition. Axial addition results in cyclopropane products, while circumferential addition produces “open” structures for both armchair and zigzag tubes. The barriers for addition of dichlorocarbene to a (5,5) SWNT, studied for a finite C 90 H 20 cluster, are higher than that for addition to C 60 , in spite of similar diameters of the carbon materials. Whereas addition of CCl 2 to [60]fullerene proceeds in a concerted fashion, addition to a (5,5) armchair SWNT is predicted to occur stepwise and involve a diradicaloid intermediate according to B3LYP, PBE, and GVB‐PP computations. Addition to C bonds of (5,5) armchair tubes resulting in the thermodynamically more stable insertion products is kinetically less favorable than that to A bonds yielding cyclopropane derivatives.