PREPARATION, STEREOCHEMISTRY AND REACTIVITY OF HYDRIDOSTANNYL COMPLEXES OF IRON AND CORRESPONDING ANIONIC COMPLEXES

Octahedral hydrido stannyl complexes of iron can be prepared by three different routes: (i) mer-(CO)3(PPh3)Fe(H)SnR3 (1a,b) or cis,cis-(CO)2 (dppe)Fe(H)SnR3 (1c,d) (R = Me, Ph) by treating the silyl complexes (CO)3(PPh3)Fe(H)SiMe3 or (CO)2(dppe)Fe(H)SiMe3 with the corresponding stannane, (ii) (CO)2[P(OPh)3]2-Fe(H)SnR3 (1f,g) by addition of HSnR3 to (CO)2[P(OPh)3]2Fe, and (iii) the SnCl3 derivatives cis,cis-(CO)2(dppe)Fe(H)SnCl3 (1e) and (CO)2[P(OPh)3]2Fe(H)SnCl3 (1h) by reaction of the corresponding dihydride complexes with SnCl4. In the complexes 1f,g the carbonyl ligands are mutually trans and the phosphite ligands are cis at room temperature. At -40°C another isomer is present which has ligands cis CO and trans phosphite ligands. This isomer is observed for 1h at room temperature. Deprotonation of the SnMe3- or SnPh3-substituted complexes by KH gives the corresponding anionic complexes K[(CO)3(PPh3)FeSnR3] (3a,b) and K[(CO)2L2FeSnR3] (3c,d: L2 = dppe; 3e,f: L = P(OPh)3). The anionic complexes react with methyl iodide or triorganyltin halides to yield methyl stannyl or bisstannyl complexes. The bisstannyl complex mer-(CO)3(Ph3P)Fe(SnMe2Cl)2 (4d) is obtained by reaction of the trimethylstannyl derivative 3a with an excess of Me2SnCl2. An X-ray diffraction study of 4d reveals that the two stannyl ligands do not interact with each other in the solid state. However, NMR spectra in nonpolar solvents indicate the presence of another isomer, which contains chloro bridges between both tin atoms. Attempts to eliminate R3ESnR′3 (E = C, Si, Sn) from iron complexes containing two main-group IV ligands on reaction with phosphines are only successful for methyl stannyl complexes. mer(CO)3(Ph3P)Fe(SnMe3)SiMePh2 eliminates the siloxy stannane Ph2MeSiOSnMe3 instead. The complexes mer-(CO)3(Ph3P)Fe(SnMe3)[Si(OEt)3] and mer-(CO)3(Ph3P)Fe(SnMe3)2 decompose under SnMe4 elimination to form [(CO)3(Ph3P)Fe(μ-SnMe2)]n. © 1990.