Dimeric piperidino-alane and -gallane: metal hydrides with a cyclic M(mu-N)(2)M core (M = Al or Ga)

The crystal structures of piperidino-alane and -gallane at 150 K have each been shown to consist of dimeric molecules [CH2(CH2)(4)NMH2](2) centred on a planar, nearly square M(mu-N)(2)M core (M = Al or Ga). The molecular structures thus contrast with the hydrogen-bridged units favoured by the sterically encumbered piperidino derivatives {[CMe2(CH2)(3)CMe2N]AlH2}(3) and {[CMe2(CH2)(3)CMe2N](2)AlH}(2) and are also compared with those of other amido derivatives of the Group 13 hydrides.