Sym. Chooi et al., STEREOELECTRONIC EFFECTS ON THE CHELATING PROPERTIES OF [2-(METHYLSULFINYL)ETHYL]DIPHENYLARSINE AND ITS PHOSPHORUS ANALOG, Tetrahedron : asymmetry, 5(9), 1994, pp. 1805-1814
A pair of internally diastereomeric platinum(II) complex cations conta
ining the orthometalated (S)-(1-(dimethylamino)ethyl)naphthalene and t
he racemic form of the sulfinyl-substituted ligand Ph(2)ECH(2)CH(2)S(O
)Me ((E-S(O), where E = As, P) has been prepared via two routes origin
ating from (S)-(+)bis(m-chloro)bis[1-[1-(dimethylamino)ethyl] -2-napht
halenyl-C,N]diplatinum(II). The crystal structure of the arsenic analo
gue (crystal data: triclinic, P1, a = 7.950(2) Angstrom, b = 17.449(3)
Angstrom, c = 21.981(4) Angstrom, alpha = 82.67(2)degrees beta = 87.0
6(2)degrees, gamma = 82.87(2)degrees, Z = 4 and R = 0.0409) shows the
ligand being coordinated to platinum(II) in both diastereomers as a bi
dentate chelate exclusively via arsenic and sulfur donor atoms. Proton
NMR studies also indicate the retention of this As-S coordination in
solution, A similar bonding mode was observed for the analogous phosph
ine complex. The E-S chelation appears to be governed by the electroni
c properties of platinum. In contrast to the previously documented pal
ladium(II) analogues, the E-O chelation is not observed in the present
series of platinum(II) compounds although there will be less severe l
igand-ligand interactions if the E-S(O) ligands fonn six-membered chel
ate rings in these square-planar systems.