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Synthesis and Structural Studies of Rhenium( V ) Complexes Stabilized by a Monoanionic Cyclen Ligand
Author(s) -
Xavier Catarina,
Paulo António,
Domingos Angela,
Santos Isabel
Publication year - 2004
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200300490
Subject(s) - cyclen , chemistry , rhenium , ligand (biochemistry) , amine gas treating , crystallography , octahedron , nuclear magnetic resonance spectroscopy , stereochemistry , cationic polymerization , crystal structure , inorganic chemistry , polymer chemistry , biochemistry , receptor , organic chemistry
Abstract The novel cationic (oxo)Re V complexes [ReO(cyclen‐H)Cl]X [X = Cl ( 3a ), BPh 4 ( 3b )] and [ReO(cyclen‐H)I]I ( 4 ) have been prepared by treating cyclen (1,4,7,10‐tetrazacyclododecane) with (Bu 4 N)[ReOCl 4 ] ( 1 ) and cis ‐[ReO 2 I(PPh 3 ) 2 ] ( 2 ), respectively. The X‐ray structural analyses of 3a and 4 , as well as 1 H NMR spectroscopy, showed that the macrocyclic ligand is coordinated in the unprecedented monoanionic form. 1 H and 13 C NMR spectroscopy also demonstrated that 3a , b and 4 exist in solution as single isomers. To the best of our knowledge, 3a and 4 are the first examples of structurally characterized oxo complexes of d transition elements with cyclen bound to the metal atom through one amido and three amine groups. In both complexes, the geometry around the Re V center is best described as distorted octahedral. The terminal oxo and halo ligands are coordinated in relative cis positions, and the amido and three amino nitrogen atoms from cyclen occupy the four remaining coordination positions. The Re−N(amido) bonds [1.894(9) Å in 3a and 1.888(12) Å in 4 ] are trans to the halo ligands and, as expected, are considerably shorter than the Re−N(amine) bonds, which span from 2.110(6) to 2.246(8) Å and from 2.124(8) to 2.268(10) Å for cations the cations of 3a and 4 , respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)