Sterically encumbered metalla-diphosphines: unlocking alkyne rotation by PtII coordinationElectronic supplementary information (ESI) available: Synthetic procedures and characterization data of all new compounds, selected NMR and CV spectra. CCDC 1541341-1541346. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7dt01803g

We present the synthesis and coordination chemistry of a series of W II alkyne complexes with symmetric and asymmetric acetylene diphosphines. Chelate-like P , P ′-coordination of PtCl 2 cause a drastic potential change of the W centered oxidation proving intermetallic cooperativity. The choice of peripheric P-substituents has a measurable influence on the potential itself as well on the respective potential change upon coordination. The enlarged deviation of the diphosphino alkyne from linearity in the dinuclear complexes unlock alkyne rotation making different isomers accessible. Chelate coordination of a redoxactive metalla-diphosphine at PtCl 2 changes the electronic structure at the alkyne complex moiety significantly, which is reflected in the onset of rotational isomerism.