Synthesis and crystal structure of 1,4-diaminobutyl-N,N′-bis(cyanoborane): the first substituted-borane adduct of putrescine

The reaction of 1,4-diaminobutane (putrescine) with two molar equivalents of trimethylaminecyanoborane in anhydrous diethyl ether, produced an unprecedented cyanoborane species, 1,4-diaminobutyl-N,N′-bis(cyanoborane) (1), in 78% yield, via a Lewis-base exchange reaction. The crystal structure showed the title compound (1) to be a zwitterionic species in which the two nitrogen atoms of a putrescine unit are coordinated to two cyanoborane units.