Dimeric piperidino-alane and -gallane: metal hydrides with a cyclic M(mu-N)2M 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)4NMH2]2 centred on a planar, nearly square M(mu-N)2M core (M = Al or Ga). The molecular structures thus contrast with the hydrogen-bridged units favoured by the sterically encumbered piperidino derivatives {[CMe2(CH2)3CMe2N]AlH2}3 and {[CMe2(CH2)3CMe2N]2AlH}2 and are also compared with those of other amido derivatives of the Group 13 hydrides.