An Efficient Route to Group 6 and 8 Metallaborane Compounds: Synthesis of <i>arachno</i>‐[Cp*Fe(CO)B₃H₈] and <i>closo</i>‐[(Cp*M)₂B₅H₉] (M = Mo, W)

Abstract

Abstract Reaction of [Cp*Fe(CO) 2 I] (Cp* = η 5 ‐C 5 Me 5 ) with an excess amount of BH 3 · thf in toluene at 75 °C or with LiBH 4 at –78 °C leads to the isolation of hydrogen‐rich ferraborane arachno ‐[Cp*Fe(CO)B 3 H 8 ] in good yield. In a similar fashion, reaction of [Cp*M(CO) 3 Cl] (M = Mo and W) with an excess amount of BH 3 · thf at 80 °C or at –78 °C with LiBH 4 yielded metallaboranes [(Cp*M) 2 B 5 H 9 ] (M = Mo, W). Isolated yields of closo ‐[(Cp*M) 2 B 5 H 9 ], (M = Mo and W), both from LiBH 4 and BH 3 · thf, are good. All compounds were characterized in solution by IR, 1 H, 11 B, and 13 C NMR spectroscopy and mass spectrometry and the structural types were unequivocallyestablished by crystallographic analysis of arachno ‐[Cp*Fe(CO)B 3 H 8 ].(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2009)