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

Self-assembly of the tetranuclear square [Re-4(CO)(12)Br-4(mu -pz)(4)] (pz = pyrazine) from the monometallic complex [Re( CO) 4 Br( pz)] in acetone at room temperature has been investigated. The mechanistic pathway is examined and proved by both in-situ H-1 NMR and ES-MS studies. Both techniques are helpful to identify three species, Re-2(CO)(8)Br-2(mu -pz), Re(CO)(3)Br(pz)(2) and Re-2(CO)(7)Br-2(mu -pz)(pz), as intermediates. The other intermediates, Re-3(CO)(11)Br-3(mu -pz)(2), Re-3(CO)(10)Br-3(mu -pz)(2)(pz), Re-4(CO)(14)Br-4(mu -pz)(3) and Re-4(CO)(13) Br-4(mu -pz)(3)(pz), detected by electrospray mass spectral techniques also support the proposed mechanistic pathway.