Boron Nitrogen Compounds
Three important compounds:
B=N isoelectronic with C=C => borazine is like benzene
(aromatic).
planar B3N3 ring, all B-N bonds
same lengths.
Due to polarity, much more reactive than benzene.
Borazine 
Boron nitride (BN)x
hexagonal 
like graphite
structure (layered)
cubic like diamond (hard)
Hexagonal (BN)x
versus Graphite
Graphite: carbon in one layer on top of a ring.
(staggered or out of registery)
Hexagonal (BN)x: B above N interlayer
interaction.
(eclipsed or in registery)
weak B-N interlayer interaction.
(BN)x less easy to cleave.
polar B-N bond means that electrons are localised,
and so
(BN)x is an electrical insulator.