Synthesis and Structure of Unprecedented Samarium Complex with Bulky Bis-iminopyrrolyl Ligand via Intramolecular C=N Bond Activation

An unprecedentate samarium complex of the molecular composition [{κ3-{(Ph2CH)N=CH}2C4H2N)}{κ3-{(Ph2CHN=CH)(Ph2CHNCH)C4H2N}Sm}2] (2), which was isolated by the reaction of a potassium salt of 2,5-bis{N-(diphenylmethyl)-iminomethyl}pyrrolyl ligand [K(THF)2{(Ph2CH)N=CH}2C4H2N)] (1) with anhydrous samarium diiodide in THF at 60 °C through the in situ reduction of imine bond is presented. The homoleptic samarium complex [[κ3-{(Ph2CH)–N=CH}2C4H2N)]3Sm] (3) can also be obtained from the reaction of compound 1 with anhydrous samarium triiodide (SmI3) in THF at 60 °C. The molecular structures of complexes 2 and 3 were established by single-crystal X-ray diffraction analysis. The molecular structure of complex 2 reveals the formation of a C–C bond in the 2,5-bis{N-(diphenylmethyl)iminomethyl}pyrrole ligand moiety (Ph2Py–). However, complex 3 is a homoleptic samarium complex of three bis-iminopyrrolyl ligands. In complex 2, the samarium ion adopts an octahedral arrangement, whereas in complex 3, a distorted three face-centered trigonal prismatic mode of nine coordination is observed around the metal ion