Synthesis and Characterization of Aza-Trimetalla Tetrahedranes

Article abstract of DOI:10.1515/znb-1996-1116

The sulfimide complex Fe₂(CO)₆(μ-SNH) (1) reacts with Co₂(CO)₈ to form a 1:1 mixture of the known clusters FeCo₂(CO)₉(μ₃-S) (2) and FeCo₂(CO)₉(μ₃-NH) (3). The aza-tetrahedrane 3 may be used as a precursor for the synthesis of the new aza-trimetalla tetrahedranes Fe₂Co(CO)₉(μ-H)(μ₃-NH) (5), CpMoFeCo(CO)₈(μ₃-NH) (6). CpNiFeCo(CO)₆(μ₃-NH) (7) and (CpNi)₂Fe(CO)₃(μ₃-NH) (8) which were obtained from exchange reactions of 3 with Na₂[Fe(CO)₄], Na[CpMo(CO)₃] and [CpNi(CO)]₂. However, the reactions of 3 with Na₂[Fe(CO)₄] and Fe₃(CO)₁₂ gave Fe₃(CO)₉(μ-H)₂(μ₃-NH) (9) only as a minor product in addition to large amounts of Fe₃(CO)₉(μ-H)₂(μ₃-S) (10). The ¹H NMR spectra of 3 and 5 -9 show a broadened triplet for the NH proton between δ(¹H) 8.21 and 9.53. Chemical shifts δ(¹⁴N) were determined most efficiently by heteronuclear ¹H{¹⁴N} double resonance experiments. The δ(¹⁴N) values for aza-trimetalla tetrahedranes (-180 to -202) indicate delocalized bonding between the μ₃-bridging nitrogen atom and the metal triangle.