CRYSTAL AND MOLECULAR STRUCTURE OF SNMEPH(C10H5(OME-5)(CH2NME2-8))BR AND PROTON NUCLEAR MAGNETIC RESONANCE STUDY OF THE PUCKERING OF THE CHELATE RING IN FIVE-COORDINATE TRIORGANOTIN HALIDES SNRR′(C10H5(OME-5)(CH2NME2-8))X AND SNRR′(CH