New dithiophosphonate complexes of nickel, cadmium, mercury and lead.
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Date
2013
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Abstract
This study was primarily focused on the synthesis and structural X-ray crystallographic
analyses of new complexes. The work undertaken investigated the reactivity of the
diphosphetane disulfide dimer, [P(4-C6H4OEt)S(S)]2, which is the phenetole analogue of the
popular Lawesson's Reagent (LR), towards the primary and secondary alcohols methanol, 2-
propanol, 1-propanol and 2-butanol. The phenetole LR dimer undergoes nucleophilic attack
when reacted with primary or secondary alcohol species, cleaving it symmetrically and
forming the respective dithiophosphonic acid, which is then readily deprotonated by
ammonia, yielding ammonium dithiophosphonato ligand salts of the type NH4[S2PR(OR’)]
(R=4-C6H4OEt) used directly in complexing metals centres. The dithiophosphonato ligands
are all bidentate and mono-anionic. New late transition-metal complexes were formed from
the reaction between [S2PR(OR’)]- with the halide or nitrate salts of Cadmium(II), Nickel(II),
Lead(II) and Mercury(II), affording both mononuclear and dinuclear complexes. Suitable
crystals of nine complexes were eventually found and subjected to X-ray crystallographic
analyses: four distorted square planar Ni(II) complexes (1A, 2A, 3A, 4A), two dinuclear
Hg(II) complexes (1B, 2B), one dinuclear Cd(II) complex (1C) and one distorted pyramidal
dimeric Pb(II) complex (2D) and an octahedral Ni(II) complex (4Ai). Additionally, all new
complexes were fully characterized by means of 31P and 1H and 13C NMR, FTIR, elemental
analysis and, as stated, single crystal X-Ray diffraction. This study initially set out to
determine if small changes in starting materials could lead to significant changes in structure
(as it often does, through unexpected hydrogen bonding, for example), but it turned out in this
study that most of the complexes prepared, although new, did not deviate significantly from
the structural details of related complexes previously prepared, which is a result in itself.
Description
M. Sc. University of KwaZulu-Natal, Durban 2013.
Keywords
Crystallography., Inorganic compounds., Nickel--Analysis., Cadmium--Analysis., Mercury--Analysis., Lead--Analysis., Theses--Chemistry.