Multinuclear copper(I) guanidinate complexes

A series of multinuclear Copper(I) guanidinate complexes have been synthesized in a succession of reactions between CuCl and the lithium guanidinate systems Li{L} (L = Me2NC(iPrN)2 (1a), Me2NC(CyN)2 (1b), Me2NC(tBuN)2(1c), and Me2NC(DipN)2 (2d) (iPr = iso-propyl, Cy = cyclohexyl, tBu = tert-butyl, and Dip = 2,6-disopropylphenyl) made in situ, and structurally characterized. The di-copper guanidinates systems with the general formula [Cu2{L}2] (L = {Me2NC(iPrN)2} (2a), {Me2NC(CyN)2} (2b), and {Me2NC(DipN)2} (2d) differed significantly from related amidinate complexes because of a large torsion of the dimer ring, which in turn is a result of transannular repulsion between adjacent guanidinate substituents. Attempts to synthesis the tert-butyl derivative [Cu2{Me2NC(tBuN)2}2] result in the separate formation and isolation of the tri-copper complexes [Cu3{Me2NC(tBuN)2}2(μ-NMe2)] (3c) and [Cu3{Me2NC(tBuN)2}2(μ-Cl)] (4c), both of which have been unambiguously characterized by single crystal X-ray diffraction. Cl...