Electronic Supplementary Information This Journal is (C) The Owner Societies 2003 A. Gregusova, I, Cernusak, O. Malkina, and J. Noga On the Structure and Stability of Cyclic Cyanoborane Isomers This supplementary material includes the DFT-B3LYP/DZP optimized geometries for (BH2CN)n and (HCBNH)n cyclic oligomers in XYZ format (BH2CN)2: C 0.194541 1.188798 -0.000096 B 1.678954 0.410704 0.000053 N 0.975004 -1.089957 -0.000077 C -0.194532 -1.188697 -0.000116 B -1.678808 -0.410976 0.000047 N -0.975040 1.090115 0.000027 H 2.265219 0.575052 -1.027679 H -2.264855 -0.574832 1.028050 H 2.264656 0.574132 1.028349 H -2.265562 -0.574700 -1.027594 (BH2CN)3: C 1.785746 0.047022 0.001460 N 1.408865 1.147600 0.001927 B 0.440806 2.375262 -0.000648 C -0.933718 1.522891 -0.001416 N -1.698200 0.646143 -0.001104 B -2.277578 -0.805901 0.002146 C -0.852033 -1.569735 -0.001501 N 0.289396 -1.793803 -0.001461 B 1.836704 -1.569448 -0.000256 H 2.329816 -1.986012 -1.012688 H -2.880515 -1.022212 1.017827 H 0.558082 3.009469 -1.013451 H -2.891916 -1.024978 -1.005852 H 2.329099 -1.989595 1.011030 H 0.555377 3.013111 1.010132 (BH2CN)4: C 0.000000 2.382693 0.000000 C 0.000000 -2.382693 0.000000 C 2.382693 0.000000 0.000000 C -2.382693 0.000000 0.000000 N 1.129645 2.118257 0.000000 N -1.129645 -2.118257 0.000000 N 2.118257 -1.129645 0.000000 N -2.118257 1.129645 0.000000 B 1.590816 -2.583089 0.000000 B -1.590816 2.583089 0.000000 B 2.583089 1.590816 0.000000 B -2.583089 -1.590816 0.000000 H -3.147643 -1.927105 1.008379 H -3.147643 -1.927105 -1.008379 H 3.147643 1.927105 1.008379 H 3.147643 1.927105 -1.008379 H 1.927105 -3.147643 1.008379 H 1.927105 -3.147643 -1.008379 H -1.927105 3.147643 -1.008379 H -1.927105 3.147643 1.008379 (BH2CN)5: C -2.727399 -1.230409 -0.007121 B -3.655998 0.069322 -0.036216 N -2.714935 1.286911 -0.018532 C -2.011574 2.209129 -0.003608 B -1.063035 3.494388 0.021445 N 0.386323 2.977311 0.013729 C 1.481868 2.596302 0.008420 B 2.997563 2.091402 0.005757 N 2.952848 0.553239 -0.005486 C 2.928835 -0.606387 -0.015670 B 2.916076 -2.203869 -0.026998 N 1.439270 -2.636048 -0.006200 C 0.328234 -2.968759 0.011765 B -1.194482 -3.451018 0.042226 N -2.063704 -2.181461 0.012547 H -1.269331 4.141527 -0.973823 H 3.532470 2.489826 -0.997735 H 3.437078 -2.583750 -1.044912 H -1.406291 -4.111585 -0.943075 H -4.292168 0.061849 -1.059552 H 3.467901 -2.596539 0.969732 H 3.528512 2.475278 1.017162 H -1.272085 4.102223 1.040764 H -4.341623 0.071476 0.954704 H -1.383493 -4.050352 1.070545 (BH2CN)6: B -0.926211 -3.657170 1.152680 B 2.786721 -2.897831 -0.855638 B 4.093185 1.152203 -0.295513 B 0.926261 3.657284 1.152499 B -2.786831 2.897842 -0.855469 B -4.093135 -1.152284 -0.295670 N -2.022512 -2.733612 0.599792 N 1.447499 -3.124958 -0.139264 N 3.580563 -0.287808 -0.461132 N 2.022530 2.733628 0.599711 N -1.447529 3.124956 -0.139244 N -3.580551 0.287756 -0.461156 C 3.228316 -1.383374 -0.606325 C 0.432360 -3.334474 0.381879 C -2.877982 -2.047216 0.221923 C -3.228329 1.383340 -0.606261 C -0.432352 3.334503 0.381810 C 2.878004 2.047185 0.221935 H -4.960445 -1.183717 0.540922 H -4.449174 -1.575968 -1.366435 H -0.756349 -3.427375 2.323941 H -1.219233 -4.805711 0.933546 H 3.624884 -3.620362 -0.377908 H 2.643619 -3.057168 -2.041912 H 4.960363 1.183560 0.541220 H 4.449413 1.575913 -1.366205 H 0.756450 3.427690 2.323806 H 1.219288 4.805785 0.933160 H -3.624965 3.620280 -0.377543 H -2.643905 3.057328 -2.041744 HCBNH: C -0.600069 -0.458163 -0.000040 B 0.848470 -0.274884 -0.000467 N -0.144321 0.780171 0.000083 H -1.631143 -0.820694 0.000570 H 1.999448 -0.517105 0.001425 (HCBNH)2: C -1.443672 -0.081720 0.117671 B -0.638453 1.311503 0.055417 N 0.750996 1.148779 0.057714 C 1.443570 0.081690 -0.118018 B 0.638421 -1.311519 -0.054997 N -0.750888 -1.148776 -0.057748 H -2.501345 -0.078908 -0.191173 H -1.210038 2.278664 -0.343451 H 2.501339 0.078891 0.190528 H 1.210051 -2.278407 0.344319 (HCBNH)3: C 1.490397 -1.325645 -0.319872 B 1.992432 0.025571 0.395002 N 1.338796 1.147114 -0.033261 C 0.403177 1.950936 -0.321844 B -1.016008 1.709131 0.397221 N -1.665245 0.585957 -0.033964 C -1.895005 -0.626665 -0.320356 B -0.973325 -1.734565 0.395140 N 0.324594 -1.730576 -0.033665 H 2.073474 -1.878884 -1.073965 H 2.823143 0.047384 1.252117 H 0.586677 2.727905 -1.081667 H -1.443362 2.411949 1.262449 H -2.666068 -0.856918 -1.073356 H -1.367788 -2.461336 1.256265 (HCBNH)4: N 0.210082 -2.084639 -0.012605 C 1.026324 -1.898621 -0.957701 B 2.034314 -0.649041 -1.039105 N 2.086384 0.210540 0.012617 C 1.898401 1.024967 0.958919 B 0.648566 2.032551 1.039861 N -0.210069 2.085593 -0.012498 C -1.025324 1.898998 -0.958326 B -2.032555 0.648873 -1.040052 N -2.086383 -0.209738 0.012373 C -1.900159 -1.026086 0.957469 B -0.649612 -2.032945 1.038956 H 0.982117 -2.595204 -1.812637 H 2.681147 -0.462374 -2.026469 H 2.593820 0.979714 1.814728 H 0.460595 2.678416 2.027641 H -0.980563 2.595442 -1.813330 H -2.677388 0.460430 -2.028414 H -2.596946 -0.982331 1.812243 H -0.461890 -2.679138 2.026560 (HCBNH)5: C -3.252107 -1.080041 -0.367915 B -2.340759 -2.380533 -0.167026 N -0.991218 -2.298884 -0.269901 C 0.260817 -2.196216 -0.406032 B 1.254536 -1.828689 0.783837 N 2.523561 -1.459888 0.449347 C 3.592677 -0.895202 0.084794 B 3.701102 0.673991 -0.251279 N 2.604003 1.436278 -0.011378 C 1.494030 1.995145 0.212895 B 0.292230 2.019685 -0.836603 N -0.952713 2.281961 -0.353462 C -2.089553 2.420891 0.176887 B -2.966318 1.241316 0.809198 N -3.083966 0.038517 0.190405 H -4.127555 -1.183999 -1.035365 H -2.873970 -3.435060 0.024940 H 0.672918 -2.325020 -1.421679 H 0.902422 -1.870682 1.923754 H 4.490388 -1.526616 -0.028089 H 4.706940 1.133306 -0.702124 H 1.344048 2.445203 1.209510 H 0.473852 1.787978 -1.993488 H -2.488454 3.448925 0.251067 H -3.537397 1.443756 1.842005 (HCBNH)6: N -3.337115 1.166246 0.763648 N -3.105044 -1.325700 -0.809565 N 0.140162 -2.813772 0.039414 N 3.336940 -1.166168 0.763824 N 3.105075 1.325766 -0.809585 N -0.140044 2.813832 0.039589 C -4.363618 0.551306 0.358283 C -1.395708 2.691077 0.111721 C 1.929769 1.760655 -0.960855 C 4.363460 -0.551426 0.358218 C 1.395823 -2.691131 0.111694 C -1.929721 -1.760498 -0.960911 B -2.101894 1.640416 1.084987 B 1.221122 2.786960 0.036274 B 4.318412 0.775033 -0.547316 B 2.101818 -1.640567 1.085196 B -1.220994 -2.786801 0.036161 B -4.318446 -0.775154 -0.547241 H -1.858915 -3.501108 0.748311 H 1.550637 -1.275502 2.079884 H 5.326429 1.249146 -0.978542 H 1.859069 3.501255 0.748411 H -1.550726 1.275042 2.079571 H -5.326412 -1.249427 -0.978413 H 5.346899 -0.958138 0.649681 H 2.008802 -3.323948 -0.552805 H -1.358392 -1.381652 -1.826898 H -5.347067 0.957830 0.649959 H -2.008625 3.323898 -0.552835 H 1.358365 1.381843 -1.826809