Data were collected on a Bruker SMART CCD diffractometer (Mo Ka , l ¼ 0.71069 ä). In all cases the selected crystals were mounted onto the tip of a glass pin using Paratone-N oil and placed in the cold flow (120 K) produced with an Oxford Cryocooling device. Complete hemispheres of data were collected using w scans (0.38, 30 s/ frame). Integrated intensities were obtained with SAINT þ [12] and corrected for absorption using SADABS. [12] Structure solution and refinement was performed with the SHELXpackage. [12] The structures were solved by direct methods and completed by iterative cycles of DF syntheses and full-matrix least-squares refinement against F 2 to give for 4: using 479 parameters and 55 restraints, wR 2 ¼ 0.5006 (12 935 unique reflections), R 1 ¼ 0.1806 (11 281 reflections with I > 2s(I)); for 5: using 299 parameters and 28 restraints, wR 2 ¼ 0.2937 (7978 unique reflections), R 1 ¼ 0.0973 (7306 reflections with I > 2s(I)); for 6: using 1204 parameters and 105 restraints, wR 2 ¼ 0.1716 (20 413 unique reflections), R 1 ¼ 0.0804 (17 353 reflections with I > 2s(I)); for 7: using 901 parameters and 108 restraints, wR 2 ¼ 0.3241 (22 002 unique reflections), R 1 ¼ 0.1140 (13 892 reflections with I > 2s(I)); for 8: using 827 parameters and 116 restraints, wR 2 ¼ 0.4806 (30 385 unique reflections), R 1 ¼ 0.1661 (17 629 reflections with I > 2s(I)); for 9: using 449 parameters and 76 restraints, wR 2 ¼ 0.5085 (9688 unique reflections), R 1 ¼ 0.1780 (7500 reflections with I > 2s(I)). CCDC-191618±191623 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam. ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre,