Table 2.
Observed spectroscopic parameters for homochiral and heterochiral dimers of styrene oxide.
| [0]RRa | [1]RRb | [2]RS | [3]RR | [4]RS | [7]RR | |
|---|---|---|---|---|---|---|
| A/MHz | 378.28285(20) | 572.181(12) | 476.41175(21) | 519.837962(47) | 565.132480(93) | 512.20992(15) |
| B/MHz | 330.824777(86) | 386.3259(45) | 399.70525(14) | 350.271983(38) | 327.768274(72) | 360.88847(11) |
| C/MHz | 249.305701(65) | 276.86249(37) | 371.57747(16) | 322.618306(39) | 307.883752(74) | 302.976455(82) |
| DK/kHz | −0.3622(31) | – | −0.1967(63) | −0.16430(21) | 0.1576(11) | −0.0235(37) |
| DJK/kHz | 0.4531(14) | – | 0.1363(66) | 0.15629(25) | −0.0458(13) | −0.0180(28) |
| DJ/kHz | 0.01625(30) | 0.03487(93) | 0.0758(14) | 0.07994(16) | 0.07401(34) | 0.06366(55) |
| δK/kHz | 0.23156(74) | – | 0.3045(86) | – | 0.0455(96) | 0.1565(36) |
| δJ/kHz | −0.00562(16) | – | 0.00558(78) | – | 0.00293(19) | 0.00636(27) |
| ∣μa∣ | y | y | n | y | y | y |
| ∣μb∣ | n | y | y | y | y | y |
| ∣μc∣ | n | n | y | y | y | y |
| N | 148 | b | 159 | 470 | 342 | 148 |
| σ/kHz | 3.7 | 6.8 | 5.6 | 4.7 | 4.9 | 3.1 |
Primary rotational constants (A,B,C) are given in MHz, and quartic centrifugal distortion constants are given in kHz. The errors for the measured values are standard errors. N is the number of lines included in the fit, and σ is the standard deviation of the fit. The experimental frequency accuracy is 25 kHz.
aRotational constants and centrifugal distortion constants for the global minimum geometry of the homochiral dimer of 2-(4-fluorophenyl)oxirane, which is predicted to be structurally equivalent to [0]RR (Supplementary Fig. 3).
bThe rotational constants shown for the [1]RR dimer correspond to a partial fit to the centre frequencies of a splitting pattern tentatively assigned to a large-amplitude motion inverting the a- and b-type dipole moment components.