Übergangsmetall-silyl-komplexe: XLII. Einfluβ des phosphan-liganden auf bildung, struktur und stabilität der hetero-zweikernkomplexe (CO) 3(R′ 3P)(R 3Si)Fe—ML n (M  Cu, Ag, Au, Hg)

Abstract

The anionic silyl complexes Na[Fe(CO) 3(PR′ 3)SiR 3] (PR′ 3  PMe 3: SiR 3  SiMePh 2, SiMe 3; PR′ 3  P nBu 3: SiR 3  SiMePh 2; PR′ 3  PPh 2H: SiR 3  SiPh 3, SiMePh 2, SiMe 2Ph) were prepared by deprotonation of the corresponding hydrido silyl complexes. They react with CH 3I or Me 3SnCl to give mer-(CO) 3(R′ 3P)(R 3Si)FeER 3 (PR′ 3  PMe 3 and PPh 2H; ER 3  CH 3, SnMe 3), while with metal complex halides XML n , (ML n ,  AuPR 3, AgPPh 2Tol, CuPR 3 Cudppe, HgPh) the hetero-binuclear complexes mer-(CO) 3(R′ 3P)R 3Si) FeML n are obtained, which contain unbridged metal—metal bonds. Upon reaction of [Fe(CO) 3(PR′ 3)SiR 3] − with HgBr 2 in THF the trinuclear complexes [ fac-(CO) 3(R′ 3P)(R 3Si)Fe] 2Hg are obtained, from which the binuclear complexes mer-(CO) 3(R′ 3P)(R 3Si)FeHgX are formed in toluene with a second equivalent of HgX 2. X-Ray structure analyses of the octahedral complexes mer-(CO) 3(Me 3P)(Ph 2MeSi)(FAuPPh 2Tol (FeAu 252.7(3) pm), mer(CO) 3(Me 3P)(Ph 2MeSi)FeAgPh 2Tol (FeAg 258.1(1) pm) and mer-(CO) 3(Me 3P)-(Ph 2MeSi)FeHgBr) (FeHg 251.5(3) pm) show that the Fe-metal bond is cis to both the PMe 3 and the SiMePh 2 ligand. The comparison of the Fe-Si, Fe-P and Fe-M bond distances indicates that the polarity of the Fe-M bond increases from M  Hg and M  Au to M  Ag. The Fe-Hg compound is loosely dimerized via unsymmetrical Br bridges (Hg-Br 253.5(3) and 306.3(1) pm).