From Alkynols to Alkynol Complexes. A Molecular Assembly Study

The solid state supramolecular assembly of prop-2-yn-1-ol and alkynediol transition metal complexes of Pt and Ni has been examined in light of the intermolecular interactions and hydrogen-bonding patterns established by alkyne monoalcohols and diols in the solid state. The analysis has been based on the crystal structure determination of the alcohols 1,1-dimethyl-3- tert -butylprop-2-yn-1-ol ( 1 ), tert -butylbis(ethyl)prop-2-yn-1-ol ( 2 ), tert -butylcyclohexylprop-2-yn-1-ol ( 3 ), and tetramethylalkynediol ( 4 ), as well as of the complexes bis(t-butylcyclohexylprop-2-yn-1-ol)M(0) (M = Pt ( 6a ) and Ni ( 6b ) and bis(t-butylcyclopentylprop-2-yn-1-ol)Pt(0) ( 7 ), integrated with the data available in the Cambridge Structural Database. It has been shown that the most common hydrogen-bond pattern is that based on a tetramer of −OH groups forming a square, a rhombus, or an open butterfly, irrespective of the molecular complexity. Larger ring systems or chains are established depending on the steric bulk of the substituents on the prop-2-yn-1-ol. Intermolecular and intramolecular hydrogen bond distances have been shown to depend on the type of alcohols, differences having largely a steric origin. The change in the Raman/IR stretching frequency of the C⋮C bond upon coordination of alkynediols to the metal centers has been examined for the nickel compounds and shown to provide a diagnostic tool for recognition of hydrogen-bond formation and typology.