Uebergangsmetall-Silyl-Komplexe XLII. Einfluss des Phosphan-Liganden auf Bildung, Struktur und Stabilitaet der Hetero-Zweikernkomplexe (CO)3(R3'P)(R3Si)Fe-MLn (M = Cu, Ag, Au, Hg)

Article abstract of DOI:10.1016/0022-328X(92)83083-T

The anionic silyl complexes Na (PR'3 = PMe3: SiR3 = SiMePh2, SiMe3; Pr'3 = PⁿBu3: SiR3 = SiMePh2; PR'3 = PPh2H: SiR3 = SiPh3, SiMePh2, SiMe2Ph) were prepared by deprotonation of the corresponding hydrido silyl complexes.They react with CH3I or Me3SnCl to give mer-(CO)3(R'3P)(R3Si)Fe-ER3 (PR'3 = PMe3 and PPh2H; ER3 = CH3, SnMe3), while with metal complex halides X-ML_n (ML_n = AuPR3, AgPPh2Tol, CuPR3 Cudppe, HgPh) the hetero-binuclear complexes mer-(CO)3(R'3P)(R3Si)Fe-ML_n are obtained, which contain unbridged metal-metal bonds.Upon reaction of ^- with HgBr2 in THF the trinuclear complexes 2Hg are obtained, from which the binuclear complexes mer-(CO)3(R3'P)(R3Si)Fe-HgX are formed in toluene with a second equivalent of HgX2.X-Ray structure analyses of the octahedral complexes mer-(CO)3(Me3P)(Ph2MeSi)Fe-AuPPh2Tol (Fe-Au 252.7(3) pm), mer-(CO)3(Me3P)(Ph2MeSi)Fe-AgPh2Tol (Fe-Ag 258.1(1) pm) and mer-(CO)3(Me3P)-(Ph2MeSi)FeHgBr) (Fe-Hg 251.5(3) pm) show that the Fe-metal bond is cis to both the PMe3 and the SiMePh2 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).