Mitigating repulsions in close quarters: Copper tells us how!

Destabilization due to d10-d10 repulsion in structurally characterized copper(I) diphosphinoamine (PPh2)2N(R) (R = H; dppa, R = iPr; dppipa) dimers such as [Cu2(dppa)2(CH3CN)(H2O)(OClO3)]ClO4 (1), is mitigated by charge transfer interaction promoted by unsymmetrical coordination. Cambridge Structural Database studies support the proposition.