Self-assembly of tetrametallic square [Re4(CO)12Br4(µ-pz)4] (pz = pyrazine) from [Re(CO)4Br(pz)]. A mechanistic approach

Abstract

Self-assembly of the tetranuclear square [Re₄(CO)₁₂Br₄(μ-pz)₄] (pz = pyrazine) from the monometallic complex [Re(CO)₄Br(pz)] in acetone at room temperature has been investigated. The mechanistic pathway is examined and proved by both in-situ¹H NMR and ES-MS studies. Both techniques are helpful to identify three species, Re₂(CO)₈Br₂(μ-pz), Re(CO)₃Br(pz)₂ and Re₂(CO)₇Br₂(μ-pz)(pz), as intermediates. The other intermediates, Re₃(CO)₁₁Br₃(μ-pz)₂, Re₃(CO)₁₀Br₃(μ-pz)₂(pz), Re₄(CO)₁₄Br₄(μ-pz)₃ and Re₄(CO)₁₃Br₄(μ-pz)₃(pz), detected by electrospray mass spectral techniques also support the proposed mechanistic pathway.