METAL COORDINATION AND HG-C BOND PROTONOLYSIS IN ORGANOMERCURY(II) COMPOUNDS - SYNTHESIS, CHARACTERIZATION, AND REACTIVITY OF THE TETRAHEDRAL COMPLEXES [(NP(3))HGR]-[(CF3)SO3] (NP(3)=N(CH(2)CH(2)PPH(2))(3) R=CH3, C2H5, C6H5)

The tetrahedral complexes [(np(3))HgR][(CF3)SO3] (np(3) = N(CH(2)CH(2)PPh(2))(3), R = CH3, C2H5, C6H5) have been prepared and characterized by MNR spectroscopy (H-1, C-13, P-31, Hg-199),and X-ray crystal structure analyses. The reactivity of the methyl and phenyl derivatives toward CH3COOH (or CF3COOH) and thiols has been investigated through GC and/or NMR measurements. In both cases protonolysis of the Hg-C bond occurs at valuable rates, under mild conditions, with formation of alkane (arene) and [(np(3))HgX][(CF3)SO3] or [(np(3))Hg(SR)][(CF3)SO3] (X = CH3COO, CF3COO; R = C6H5, p-CH3C6H4, C(CH3)3) Kinetics of the acetolysis suggests that, although the coordination of the three phosphorus atoms to the metal center does not substantially change the accepted mechanism of the protonolysis of the organomercurials, the resulting activation of the Hg-C bond strongly accelerates the cleavage reaction. In the case of the reaction with thiols the mechanism appears more complicated, the basicity of the amino group of np(3) playing a determining role. Crystallographic data are as follows: [(np(3))-Hg(CH3)][(CF3)SO3] .toluene, 3, Pb2(1)a, a = 34.491(12) Angstrom, b = 12.694(5) Angstrom, c = 11.184(5) Angstrom, Z = 4, R = 0.060, R(W) = 0.059; [(np(3))Hg{S(p-CH3C6H4)}][(CF3)SO3], 9, P2(1)/a, a = 17.509(9) Angstrom, b = 16.805(7) Angstrom, c = 17.870(8) Angstrom, beta = 113.83(6)degrees, Z = 4, R = 0.067, R(W) = 0.066. In both complexes the metal displays a distorted tetrahedral geometry, with the nitrogen atom of the tripod ligand being uncoordinated.