Synthesis and Structural Characterization of the\n{[Rh₅(CO)₁₄]−(H₂N(CH₂)₄NH₂)−[Rh₅(CO)₁₄])}^2- and\n[Rh₅(CO)₁₃(H₂N(CH₂)₂NH₂)]^- Anions (as [PPh₄]⁺ Salts): \nAn Unprecedented Example of Carbonyl Substitution by Alkylamines in\na Homoleptic Metal Carbonyl Cluster Anion

Abstract

The substitution of one or two carbonyls by many different primary and secondary alkylamines and -diamines has\nbeen established for the first time in a homoleptic carbonyl cluster anion, the trigonal bipyramidal [Rh₅(CO)₁₅]^-.\nTwo derivatives, the bis-monosubstituted {[Rh₅(CO)₁₄]−(H₂N(CH₂)₄NH₂)−[Rh₅(CO)₁₄]}^2- dianion (<b>1</b>) and the\ndisubstituted chelated [Rh₅(CO)₁₃(H₂N(CH₂)₂NH₂)]^- monoanion (<b>2</b>), have been structurally characterized, both in\nthe solid state (as [PPh₄]⁺ salts) and in solution, revealing that the sites of the substitution are the cluster apexes.\n¹³C NMR spectra of <b>2</b> revealed localized fluxionality of the CO ligands over the temperature range 298−183 K.