Electronic Supporting Information for ‘Double Addition of H 2 to Transition Metal–Borane Complexes: a ‘Hydride Shuttle’ Process Between Boron and Transition Metal Centres’ Nikolaos Tsoureas, Yu-Ying Kuo, Mairi F. Haddow and Gareth R. Owen The School of Chemistry, University of Bristol, Cantock’s Close, Bristol, UK, BS8 1TS Experimental General considerations: All manipulations were performed in a Braun glovebox with an O 2 and H 2 O atmosphere of below 5 ppm or by using standard Schlenk techniques. K[Tai], S1 [Rh(NBD)Cl] 2 S2 and 2 S3 were prepared according to literature procedures. PCyp 3 (Cyp = cyclopentyl) was purchased from Aldrich and was stored in the glovebox in a Young’s ampoule as a 50 mg/mL solution in toluene. P t Bu 3 was purchased from Strem and was kept in the glovebox. PMe 3 was purchased from Aldrich as a 1.0 M solution in THF and stored in a Young’s ampoule. Toluene was dried by refluxing over K and distilled under a N 2 atmosphere. THF was dried over Na/benzophenone and distilled under a N 2 atmosphere. DCM was dried using a Grubbs’ alumina system and kept in Young’s ampoules under N 2 over molecular sieves (4 Å). Dry n-pentane (<0.05 ppm H 2 O) was purchased from Fluka and was kept in a flame-dried Young’s ampoule under N 2 over molecular sieves (4 Å). Deuterated toluene and C 6 D 6 were degassed by three freeze-thaw cycles, dried by refluxing over K or Na/benzophenone respectively for 12 hours, vacuum distilled and kept in a flame- dried Young’s ampoule over 4 Å molecular sieves under N 2 . 1 H-NMR, 11 B{ 1 H}-NMR, 11 B- NMR and 31 P{ 1 H}-NMR spectra were recorded on a JEOL ECP300 spectrometer operating at 300 MHz ( 1 H). 1 H{ 11 B}-NMR experiments were recorded on a JEOL Lamda 300 spectrometer operating at 300 MHz ( 1 H). 13 C{ 1 H}-NMR spectra and correlation experiments were recorded on a Varian VNMR S500 operating at 500 MHz ( 1 H). The spectra were referenced internally, to the residual protic solvent ( 1 H) or the signals of the solvent ( 13 C). 11 B{ 1 H}-NMR and 11 B-NMR spectra were referenced externally relative to BF 3 OEt 2 . 31 P{ 1 H}-NMR were referenced externally relative to 85% H 3 PO 4 in D 2 O. Mass spectra were recorded on a VG Analytic Quattro in ESI + mode. Elemental analyses were performed at the microanalytical laboratory of the School of Chemistry at the University of Bristol. Infrared spectra were recorded on a Perkin-Elmer Spectrum 100 FTIR spectrometer (solid state, neat) from 4000 cm -1 to 650 cm -1 . Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010