Nickel complexes dithiophosphates

Table 4 Bis(dithiophosphate)nickel(II) complexes with N-donor ligands...

Among the numerous nickel dithiophosphates, the chiral complexes deserve to be cited.41 Unusual trinuclear Pd3(p3-E)2[S2P(OR)2]2(PPh3)2 with E = S, Se, R = Et, Pr, Pr, Bu, have been prepared and Pd3(p3-S)2[S2P(OEt)2]2(PPh3)2 revealed a structure containing three distorted square-planar Pd atoms and sharing two p3-S ligands.42... 

Bis(dialkyldithiophosphinato)nickel(II) complexes were prepared by the direct synthesis of an alkali metal or ammonium salt of the dithiophosphinic acid and a nickel salt in aqueous solution.2039,2061"2063 Ni(S2AsR2)2 and Ni(Se2PR2)2 complexes were prepared in a similar way.2064"2066 All of these complexes are square planar like their dithiophosphate analogues. X-Ray crystal structures of the complexes Ni(S2PR2)2, with R = Me,2067 Et, Ph,1983 R2 = Me/ Et 2°w r2 = Me/2-thienyl,2069 and Ni(Se2PPh2)21984 have been reported (Table 90). 

In the presence of bis(0,0-dibenzyl)dithiophosphate)nickel(II) the hydrolysis at pH g of p-nitrophenyl picolinate (PNPP) (67) was enhanced more than a 1000-fold. The proposed mechanism of this biomimetic model involved the intramolecular attack of a metal hydroxide species on the bound ester. An unsymmetrical bis-Schiff base Mn(III) complex with a morpholino pendant (68 M=MnCl) also catalysed the alkaline hydrolysis of PNPP (67) very effectively, but was not so effective as a catalyst as Co and Mn complexes with a benzo-lO-aza-crown ether pendant (69 M = MnCl, M = Co). One of the latter (69 M = MnCl) showed an enhancement factor at pH 7.6 of 1.67 X 10 ... 

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