Antimony(i) → Pd(ii) complexes with the (μ-Sb)Pd coordination framework.

The reaction of the antimony(i) compound ArSb (1) (where Ar = CH-2,6-(CH[double bond, length as m-dash]NtBu)) with various dimeric allyl palladium(ii) complexes [Pd(η-allyl)(μ-X)] (where allyl = CH or CHMe; X = Cl or CFCO) in a 1 : 1 stoichiometric ratio gave unique complexes with the μ-ArSb moiety bridging two palladium fragments, i.e. [{Pd(η-CH)Cl}(μ-ArSb)] (2), [{Pd(η-CHMe)Cl}(μ-ArSb)] (3) and [{Pd(η-CH)(CFCO)}(μ-ArSb)] (4). Compound 1 serves formally as a 4e donor in 2-4. The treatment of 2 with another equivalent of ArSb led to the formation of the [Pd(η-CH)(Cl)(μ-ArSb)] complex (5), proving that 1 is able to function as a 2e donor in target complexes as well. The structures of 2-5 were described in detail both in solution (NMR and mass spectrometry) and in the solid state (single crystal X-ray diffraction analysis). DFT methods were used to compare bonding in the 1 : 1 (5) and 1 : 2 (2) complexes. Furthermore, a comprehensive Sb Mössbauer spectroscopic investigation of complexes 2 and 5 along with parent ArSbCl (6) and 1 was performed. For comparison, complexes [Fe(CO)(ArSb)] (7) and [Mo(CO)(ArSb)] (8) were also included in this study.