In order to prepare a 1 Degree amine from an alkyl halide with simultaneous addition of one CH2 group in the carbon chain, the reagent used as source of nitrogen is ____________ .
4-Nitrotoluene is treated with bromine to get P. 'P' is reduced with Sn/HCl to get compound 'Q\ 'Q' is diazotised and the product is treated with phosphinic acid to get compound 'R'. 'R' is oxidised with alkaline KMn04 to get 'S'. Compound 'S' is