The reaction of co-ordinated nitrogen bases with gaseous or liquid hydrogen halides, hx (x = c1, br).

Abstract

When gaseous hydrogen chloride was passed over the nickel complex, NiC12.PY2 (py = pyridine), there was a small' but detectable increase in mass. This increase in mass suggested that the hydrogen halide protonated the co-ordinated nitrogen on the pyridine ligand thus giving the complex This thesis describes a systematic study undertaken to investigate:- (i) Whether such an increase could be made quantitative by working under more favourable conditions namely, using liquid hydrogen chloride ii) How general the reaction is by use of other metal ions and ligands other than pyridine. During these studies, the bromo complexes were studied uslng liquid hydrogen bromide. On the other hand, chloro complexes were studied in liquid hydrogen chloride. The following complexes were studied ( i) (MX.Py2 = Mn, Fe, Co, ih; X = Cl, Br) 2 .L (L = 1,10 - Phenanthroline, 2,2' bipyridine and ethylenpdiamine) Ciii) (M = Cr, Mo; x = Cl, Br) The results show that liquid hydrogen halicJes, IIX( = Cl, Br') :react wi-th co-ordinated bases in p y r-i dine, 1,10 - phenanthroline, 2,2' - bipyridine and e t hy Le ne d i ami nc I to give halo complexes.NiC12"PY2 and NiBr2.pY2 react as follows I,tl i III only one exception namely MoC13· PY3' all t hr: 0 t he rcomplexes react similarly. The iron complexes, ['e<:12' PY2 and feBr2.pY2 reacted but the products isolated appeared Tillpuce. This reaction provides a new route for the synthesis of h<l lo complexes containing the pyr i d i n ium r o n or' ot hc c pro t o n at c d nit:rogen base cations. In fact the complexes (Py!l)7Ni13r" ancl( p yl i ) 3C:rBr6 have been prepared for the first L i IIIC using this technique. Another important observation made during t ho p re s c n t WOrk is the fact that the position of the me t a Lv n i tro ge n vibrational modes can be uetermined very readily w i t ho ut t ho need for isotopic substitution. For example the far infrared spectrum of NiBr2. PY2 shows a peak at 2lfO complex has been treated with liquid IIBr, 't lio pe.rk JS a bs o n I -1 CJn HIl!'J1 thc in tile product, namely (pyH)2NiBr4' The obscllt peAk is the OJIC due to v(M - N). The technique was used for assi.gnment of v(M - N) peaks in the other complexes. In agreement with those of other workers who have clone so, us ing other techniques" During :the present wor-k , ba nd assignment for the v(M- N) vibrations have been lIlaJe for the first time for the complexes CoC12"PY2 and NiBr2"PY2"