Synthesis, structure and bonding in pentagonal bipyramidal cluster compounds containing a cyclo-Sn5 ring, [(CO)3MSn5M(CO)3]4− (M = Cr, Mo)

Journal article

In this paper, we report the synthesis and structural characterisation of two hetero-metallic clusters, [(CO)₃CrSn₅Cr(CO)₃]⁴⁻ and [(CO)₃MoSn₅Mo(CO)₃]⁴⁻, both of which have a pentagonal bipyramidal core. The structures are similar to that of previously reported [(CO)₃MoPb₅Mo(CO)₃]⁴⁻ and our analysis of the bonding suggests that they are best formulated as containing Sn₅⁴⁻ rings bridging two zerovalent M(CO)₃ fragments. The electronic structure is compared to two isolobal M2E₅ clusters, [CpCrP₅CrCp]⁻ and Tl₇⁷⁻, both of which show clear evidence for trans-annular bonds between the apical atoms that is not immediately obvious in the title clusters. Our analysis shows that the balance between E-E and M-M bonding is a delicate one, and shifts in the relative energies of the orbitals on the E₅ and M₂ fragments generate a continuum of bonding situations linked by the degree of localisation of the cluster LUMO.

Authors: Mondal, S; Chen, W-X; Sun, Z-M; McGrady, JE

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: MDPI
• Journal: Inorganics
• Volume: 10
• Issue: 6
• Article number: 75
• Publication date: 2022-05-30
• Acceptance date: 2022-05-26
• DOI: 10.3390/inorganics10060075
• EISSN: 2304-6740
• Language: English
• Keywords: FFR; Zintl clusters; Density Functional Theory; X-ray crystallography