Übergangsmetall‐Silyl‐Komplexe, 48. Synthese neuartiger heteronuklearer Silyl‐Zweikernkomplexe (OC)3(R3Si)Fe(μ‐PR′R″)Pt(1,5‐COD)(Fe‐Pt), Phosphan‐Austauschreaktionen an (OC)3 (R3Si)Fe(μ‐PR′R″)Pt(PPh3)2(Fe ‐ Pt) und Darstellung der Dihydrido‐Komplexe [(OC)3Fe(μ‐PPh2)(μ‐H)2Pt(PR3)2][BF4](Fe ‐ Pt)

Abstract

Transition Metal Silyl Complexes, 48[1]. ‐ Synthesis of the New Heterobimetallic Dinuclear Silyl Complexes (OC)3(R3Si)‐Fe(μ‐PR′R″)Pt(1,5‐COD)(Fe‐Pt), Phosphane Exchange Reactions of (OC)3(R3Si)Fe(μ‐PR′R″)Pt(PPh3)2(Fe‐Pt), and Preparation of the Dihydrido complexes [(OC)3Fe(μ‐PPh2)(μ‐H)2Pt(PR3)2][BF4](Fe‐Pt)The dinuclear, silyl‐substituted complexes (OC)3(R3Si)Fe(μ‐PR′r″)Pt(1,5‐COD) (1) [μ‐PR′R″ = PPh2, PCY2, PHPh; SiR3 = SiPh3, Si(OMe)3] were prepared in high yields by the oxidative addition of the hydrido complexes (OC)3(PHR′R″)Fe(H)‐SiR3 to Pt(1,5‐COD)2. Upon reaction of (OC)3(R3Si)Fe(μ‐PR′R″)Pt(PPh3)2 [μ‐PR′R″ = PPh2, PHCy; SiR3 = SiPh3, SiPh2Me, SiPhMeCl, Si(OMe)3] with two equivalents of PR (PMe3, PBu3, PEt3) or with one equivalent of chelating di‐phosphanes (vdpp, dppe, dppm) both PPh3 ligands are displaced, and (OC)3(R3Si)Fe(μ‐PR′R″)Pt(PR)2 or (OC)3(R3Si)‐Fe(μ‐PR′R″)Pt[(PPh2)2X] (X = CCH2, C2H4, CH2) are formed, respectively. When one equivalent of PMe3 is used, only the PPh3 ligand trans to the μ‐PPh2 bridge is substituted, and (OC)3(Ph3Si)Fe(μ‐PPh2)Pt(PPh3)(PMe3 is formed. The 1,5‐COD ligand in 1 is displaced by P(OR)3 to give (OC)3‐(Ph3Si)Fe(μ‐PPh2)Pt[P(OR)3]2 (R = Me, Ph). The complexes (OC)3(Ph3Si)Fe(μ‐PPh2)Pt(PMe3)2and (OC)3(Ph3Si)Fe(μ‐PPh2)Pt[(PPh2)2CCH2] were characterized by X‐ray structure analysis. The short Fe‐Si distances [233.0(2) and 235.6(3) pm] and the infrared v(CO) absorptions indicate that the Fe‐Pt bonds are quite polar. Protonation of (OC)3(Me2‐PhSi)Fe(μPPh2)Pt(PPh3)2 with CF3COOH gives the hydrido‐bridged complex [(OC)3(Me2PhSi)Fe(μ‐PPh2)(μ‐H)Pt‐(PPh3)2][O2CCF3]. Upon addition of an excess of HBF4 · Et2O to (OC)3(R3Si)Fe(μ‐PPh2)Pt(PPh3)2 (R = Ph, OMe), (OC)3‐Si)Fe(μ‐PPh2)Pt[Pt[P(OMe)3]2 or (OC)3(Ph2MeSi)Fe(μ‐PPh2)‐Pt(dppe) R3SiF is split, and the corresponding μ‐dihydrido complexes [(OC)3Fe(μ‐PPh2)(μ‐H)2Pt(PR3)2][BF4] are obtained.