Issue 5, 2005

Linear and cyclic tetranuclear copper(i) complexes containing anions of N,N′-bis(pyrimidine-2-yl)formamidine

Abstract

The reaction of Kpmf (pmf = anion of N,N′-bis(pyrimidyl-2-yl)formamidine, Hpmf) with CuSCN afforded the complexes K[Cu4(pmF)3(SCN)2], 1, and Cu4(pmf)4, 2. Reaction of 1 with [(n-Bu)4N]PF6 in THF gave the complex [(n-Bu)4N][Cu4(pmf)3(SCN)2], 3. Their structures were characterized by X-ray crystallography. Complexes 1 and 3 are the first linear tetranuclear complexes containing only Cu(I) atoms, while complex 2 is cyclic. The four Cu(I) atoms of complexes 1 and 3 are helically bridged by three tetradentate pmf ligands. The [Cu4(pmf)3(SCN)2] anions of 1 show weak interactions with adjacent [K(THF)5]+ cations through the sulfur atoms, forming infinite chains which are subjected to a series of intermolecular π–π interactions. In complex 2, the pmf ligands are coordinated to the copper atoms in bidentate fashion through the two central amine nitrogen atoms, leaving the pyrimidine nitrogen atoms uncoordinated. Unexpected fluxional behaviors were observed for complexes 1 and 3 in solution. By the DNMR analysis, the free energy of activationGc) for the exchange is 12.8 kcal mol−1 at 278 K (Tc), and the rate constant of exchange (Kc) is 470 s−1 for 1. The ΔGc and Kc are 12.6 kcal mol−1 at 273 K and 433 s−1, respectively, for 3.

Graphical abstract: Linear and cyclic tetranuclear copper(i) complexes containing anions of N,N′-bis(pyrimidine-2-yl)formamidine

Supplementary files

Article information

Article type
Paper
Submitted
26 Nov 2004
Accepted
11 Jan 2005
First published
26 Jan 2005

Dalton Trans., 2005, 985-990

Linear and cyclic tetranuclear copper(I) complexes containing anions of N,N′-bis(pyrimidine-2-yl)formamidine

Z. Chan, Y. Wu, J. Chen, C. Yeh, C. Wang, Y. Tsai and J. Wang, Dalton Trans., 2005, 985 DOI: 10.1039/B417911K

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