Alkynyl(diphenylphosphine) d8 (Pt, Rh, Ir) Complexes: Contrasting Behavior Toward cis-[Pt(C6F5)2(thf)2].

Abstract

The synthesis and characterization of a series of mononuclear d8 complexes with at least two P-coordinated alkynylphosphine ligands and their reactivity toward cis-[Pt(C6F5)2(THF) 2] are reported. The cationic [Pt(C6F5)- (PPh2C=CPh)3](CF3SO3), 1, [M(COD)(PPh2C=CPh)2](CIO4) (M = Rh, 2, and Ir, 3), and neutral [Pt(o-C6H4E2)-(PPh 2C=CPh)2] (E = O, 6, and S, 7) complexes have been prepared, and the crystal structures of 1, 2, and 7·CH 3COCH3 have been determined by X-ray crystallography. The course of the reactions of the mononuclear complexes 1-3, 6, and 7 with cis-[Pt(C6F5)2(THF)2] is strongly influenced by the metal and the ligands. Thus, treatment of 1 with 1 equiv of cis-[Pt(C6F5)2(THF)2] gives the double inserted cationic product [Pt(C6F5)(S)μ-{C-(Ph)= C(PPh2)C(PPh2)=C(Ph)(C6F5)}Pt(C 6F5)(PPh2C=CPh)](CF3SO3) (S = THF, H2O), 8 (S = H2O, X-ray), which evolves in solution to the mononuclear complex [(C6F5)(PPh2C=CPh) Pt{C10H4-1-C6F5-4-Ph-2,3- κPP′(PPh2)2}](CF3 SO3), 9 (X-ray), containing a 1-pentafluorophenyl-2,3-bis(diphenylphosphine)-4- phenylnaphthalene ligand, formed by annulation of a phenyl group and loss of the Pt(C6F5) unit. However, analogous reactions using 2 or 3 as precursors afford mixtures of complexes, from which we have characterized by X-ray crystallography the alkynylphosphine oxide compound [(C6F 5)2Pt(μ-κO:η2-PPh 2(O)C=CPh)]2, 10, in the reaction with the iridium complex (3). Complexes 6 and 7, which contain additional potential bridging donor atoms (O, S), react with cis-[Pt(C6F5)2-(THF) 2] in the appropriate molar ratio (1:1 or 1:2) to give homo- bi- or trinuclear [Pt(PPh2C=CPh)(μ-κE-o-C6H 4E2)-(μ-κP:η2-PPh 2C=CPh)Pt(C6F5)2] (E = O, 11, and S, 12) and [{Pt(μ3-κ2EE′-o-C 6H4E2)(μ-κP:η2-PPh 2C≡ CPh)2}{Pt(C6F5) 2}2] (E = O, 13, and S, 14) complexes. The molecular structure of 14 has been confirmed by X-ray diffraction, and the cyclic voltammetric behavior of precursor complexes 6 and 7 and polymetallic derivatives 11-14 has been examined.