Hexacyanometalate Molecular Chemistry: Heptanuclear Heterobimetallic Complexes; Control of the Ground Spin State

✍ Scribed by Valérie Marvaud; Caroline Decroix; Ariane Scuiller; Carine Guyard-Duhayon; Jacqueline Vaissermann; Florence Gonnet; Michel Verdaguer

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 388 KB
• Volume: 9
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200390192

✦ Synopsis

Abstract

Following a bottom‐up approach to nanomaterials, we present a rational synthetic route from hexacyanometalates [M(CN)~6~]^3−^ (M=Cr^III^, Co^III^) cores to well‐defined heptanuclear complexes. By changing the nature of the metallic cations and using a localised orbital model it is possible to control and to tune the ground state spin value. Thus, with M=Cr^III^, d^3^, S=3/2, three heptanuclear species were built and characterised by mass spectrometry in solution, by single‐crystal X‐ray diffraction and by powder magnetic susceptibility measurements, [Cr^III^(CNM′L~n~)~6~]^9+^ (M′=Cu^II^, Ni^II^, Mn^II^, L~n~=polydentate ligand), showing spin ground states S~G~=9/2 [Cu^II^], with ferromagnetic interactions J~Cr,Cu~=+45 cm^−1^, S~G~=15/2 [Ni^II^] and J~Cr,Ni~=+17.3 cm^−1^, S~G~=27/2 [Mn^II^], with an antiferromagnetic interaction J~Cr,Mn~=−9 cm^−1^, (interaction Hamiltonian ℋ︁=−J~Cr,M~ [S~Cr~Σ~i~S~M~(i)], i=1–6). With M=Co^III^, d^6^, S=0, the heptanuclear analogues [Co^III^(CN−M′L~n~)~6~]^9+^ (M′=Cu^II^, Ni^II^, Mn^II^) were similarly synthesised and studied. They present a singlet ground state and allow us to evaluate the weak antiferromagnetic coupling constant between two next‐nearest neighbours M′CoM′.