Nuclear Quadrupole Coupling Constants

in 1-Chloroadamantane




Ellis et al. [1] measured the chlorine nqcc's in 1-chloroadamantane and determined a substitution CCl bond length of 1.8283 Å.  Chadwick et al [2] derived an effective structure with CC = 1.541 Å and CCl = 1.790 Å under the assumption that all angles are tetrahedral and all CH bond lengths are 1.09 Å.
Calculation of the chlorine nqcc's was made (i) on the structure of Chadwick et al., (ii) on this structure but with the CCl bond distance of Ellis et al., and (iii) on a structure given by MP2/6-311+G(d,p) optimization with approximate equilibrium CCl and CH bond lengths (~ re).  Calculated and experimental nqcc's are shown in Table 1.  Structure parameters (iii) are shown in Table 2.


Table 1.  Chlorine nqcc's in 1-Chloroadamantane (MHz).

Calc. (iii) MP2/6-311+G(d,p) with ~ re(CCl) = 1.8000 Å.
Calc. (i) Chadwick CCl = 1.790 Å.
Calc. (ii) Ellis CCl = 1.8283 Å.



Expt. [1]


35Cl eQq - 67.03 (iii) - 66.321(5)
- 67.50  (i)

68.10  (ii)


37Cl eQq - 52.83 (iii) - 52.277(5)
- 53.20  (i)

53.67  (ii)




Table 2.  MP2/6-311+G(d,p) C-C bond lengths and CCC angles (bridgehead) in 1-X-adamantane, where X = CN, Cl, Br, and I (Å and degrees).  For comparison, in adamantane optimized at the same level of theory, all C-C = 1.5366 Å and CCC = 109.36o.  The complete (iii) structure of 1-chloroadamantane is given here in Z-matrix format.
X = CN   Cl   Br   I
CC (bridgehead) 1.5447 1.5283 1.5293 1.5309
CCC (bridgehead) 109.27 110.07 110.15 110.17
CC (column) 1.5355 1.5383 1.5397 1.5411
CC (base) 1.5360 1.5362 1.5356 1.5353


The rotational constant calculated on the MP2/6-311+G(d,p) structure (iii) is 841.03 MHz, whereas the experimental rotational constant is


[1] M.C.Ellis, A.C.Legon, C.A.Rego, and D.J.Millen, J.Mol.Struct. (Theochem) 200,353(1989).
[2] D.Chadwick, A.C.Legon, and D.J.Millen, J.Chem.Soc.(A) 1116(1968).


1-Fluoroadamantane:  A.C.Legon, J.Tizard, and Z.Kisiel, J.Mol.Struct. 612,83(2002).


1-Bromoadamantane 1-Iodoadamantane 1-Cyanoadamantane
t-Butyl Chloride t-Butyl Bromide t-Butyl Iododine
t-Butyl Cyanide


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Last Modified 2 Nov 2009