Reactions of cyclic bis(amino)germylenes and -stannylenes with [CpFe(CO)2]2 and CpFe(CO)2Me (Cp = .eta.5-C5H5) : syntheses and single-crystal x-ray structures of four new insertion compounds

Abstract

The interaction of El(NtBu)2SiMe2, El = Ge, Sn with CpFe(CO)2Me in toluene has yielded CpFe(CO)2[El(NtBu)2SiMe2]Me, El = Ge (2) and El = Sn (3), respectively. Both compounds have been characterized by NMR, IR, MS, elemental analysis, and single crystal X-ray methods. Compound 2 crystallizes in the monoclinic system, space group P21/m, Z = 2, a = 9.330(6) A°, b = 12.552(9) A°, c = 9.939(7) A°, ß = 105.01(2)°, V = 1124(1) A°3. The isostructural 3 forms orthorhombic crystals of space group Pnma, Z = 4, a = 17.871(9) A°, b = 12.998(7) A°, c = 9.838(5) A°, V = 2285(2) A°3. The refinement of 2 with 1431 unique, observed (I > 2s(I)) reflections led to final agreement indices of R = 0.043, Rw = 0.048. The structure of 3 was refined to R = 0.027 (Rw = 0.027) by using 1397 unique and observed (I > 2s(I)) reflections. Treatment of [CpFe-(CO)2]2 with 2 equiv. of El(NtBu)2SiMe2 under identical reaction conditions afforded [CpFe(CO)2]2Ge(NtBu)2SiMe 2, 4, for the cyclic germylene, whereas in the case of the tin homolog the tetranuclear complex {[CpFe(CO)2Sn(NtBu)2SiMe2] 2·C7H8}, 5, was isolated. Complete characterizations (NMR, IR, MS, EA, single crystal X-ray determination) were carried out on both compounds. The solid state structure of 5 contains one of the longest (2.992(2) A°) unbridged tin-tin bonds known to date. The trinuclear compound 4 is triclinic, space group P1, Z = 2. Its lattice parameters are: a = 9.549(5) A°, b = 10.102(5) A°, c = 16.438(8) A°, a = 81.98(4)°, ß = 74.00(3)°, ? = 62.80(3)°, V = 1355(1) A°3. Refinement of this structure using 3100 unique, observed (I > 2s(I)) data led to agreement indices of R = 0.023 and Rw = 0.023. The tetranuclear 5 crystallizes as a toluene solvate. Crystal data: monoclinic, space group P21/n, Z = 2, a = 10.547(7) A°, b = 19.944(11) A°, c = 11.366(7) A°, ß = 92.36(5)°. Of 3024 collected data 2724 were considered unique and observed (I > 3s(I)) and used in the refinement. Final agreement indices are R = 0.031, Rw = 0.033.