cis Influence in trans-Pt(PPh₃)₂complexes

Abstract

The cis influence of a series of anionic ligands X and Y has been evaluated through the magnitude of the Pt-P coupling constants for compounds of formula trans-[PtXY(PPh(3))(2)]. The order of decreasing cis influence was found to be I > Cl > SePh approximately SPh approximately SEt > NO(3) > AcO approximately NO(2) > H > Me > Ph > mtc (mtc = N,N-dimethylmonothiocarbamato-S); moreover, the cis influences of the various ligands was found to be additive. The X-ray structures of three representative compounds (t-: X = Cl, Y = NO(3); t-: X = Cl, Y = AcO and t-: X = Y = NO(2)) have also been determined.

Quantification of cis and trans influences in [PtX(PPh3)3]+ complexes. A 31P NMR study

“…The former sequence is like that obtained in the case of type A and B complexes [14,21] and similar to what is usually reported in the literature [16,18,19], showing that this order is independent on the charge of the complex. The trans sequence differs from that obtained for type B complexes only for the position of I, which was found lower than Cl, but was probably affected by some uncertainty [14].…”

“…On the other hand the cis influence is related to the ability of the influencing ligand to lower the positive charge on the metal [21], a mechanism confirmed also by our 31 P NMR and DFT investigations [14,21]. Thus the strongest cis influence is displayed by I, Br and Cl which, being both r and p donors to Pt(II) [40], decrease efficaciously the positive charge on the metal [22,41].…”

“…In a first paper [21] we have used the one bond Pt-P coupling constants to evaluate the order of cis influence of some anionic ligands X and Y in a series of trans-[PtXY(PPh 3 ) 2 ] complexes (type A, see Scheme 1). In these compounds the mutual trans influence of the two phosphine groups can be considered constant throughout the series, consequently 1 J PtP of the various derivatives give an insight of the cis influence of X and Y.…”

“…The difference between 1 J PtP of the Cl derivative with that of a compound with a given X, gives an estimate of such ability, i.e. how much X influences the Pt-P bonds (either cis or trans) with respect of Cl [14,[10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Coordination Chemistry of Perhalogenated Cyclopentadienes and Alkynes, XXIX. The Reaction of Ni(0) and Pt(0) Phosphane Complexes with Trichloroethene, Hexachloro- and Hexabromocyclopentadiene

“…The initially observed intense colors hint on the formation of the C 5 Cl 5 radical [19]. [22]. From the NMR tube solutions some colorless crystals precipitated, which were shown by X-ray crystallography to be a new modification of trans-[Pt(PPh 3 ) 2 Cl 2 ] (see Fig.…”