Monophosphine-boranes complexes

Standard cyclisation methodology was used to access the cyclic monophosphinic acid derivative 78 by reaction of ammonium phosphonate and ethyldiisopropylamine, followed by the addition of chlorotrimethylsilane, with 2,2 -bis (bromomethyl)-l,l -biphenyl. Silane reduction of 78 gave the secondary phosphine. The secondary phosphine borane complex 79 could be used in alkylation or Michael addition reactions. For example the Michael adduct 80 was produced in high yield by treatment of 78 with a NaH suspension in THF followed by the addition of diethylvinylphosphonate . 

Examples of iron rj -B=C complexes of a boraalkene are known as well. The Fe(CO)4 complex of 9-fluorenylidene(tetramethylpiperidino)borane (126) has recently been prepared by the thermal reaction of the borane and (2) or by the photolytic reaction of (1) and the borane. The monophosphine/phosphite complexes are prepared from the tetracarbonyl by photolytic CO dissociation, followed by PRb addition. ... 

Scheme 2 Formation of zwitterionic Ni complexes upon coordination of monophosphine-boranes...

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