Synthesis of the silver(i) complex of CH2[CH(pz4Et)2]2 containing the unprecedented [Ag(NO3)4]3? anion: A general method for the preparation of 4-(alkyl)pyrazolesElectronic supplementary information (ESI) available: Crystal packing diagram of the unit cell of [Ag2{-CH2[CH(pz4Et)2]2}2]3[Ag(NO3)4]2(ac