Multinuclear and Dynamic NMR Study of trans-[Pt(Cl)(PHCy2)2(PCy2)], [Pt(Cl)(PHCy2)3][BF4], [Pt(Cl)(PHCy2)3][Cl], trans-[Pt(Cl)(PHCy2)2{P(S)Cy2}], and trans-[Pt(Cl)(PHCy2)2{P(O)Cy2}]. Influence of Intramolecular PO···H−P and Cl···H−P Interactions on Restricted Rotation about Pt−P Bond. X-ray Structure of trans-[Pt(Cl)(PHCy2)2{P(O)Cy2}]

Dynamic NMR experiments on trans-[Pt(Cl)(PHCy2)2{P(X)Cy2}] z where X is a lone pair (1, z = 0), H (2, z = +1), S (3, z = 0), or O (4, z = 0) show that the rotation around the P(X)−Pt bond is hindered for all molecules studied, with ΔG ⧧ ranging from 8.2 to 11.0 kcal/mol. The highest value of the series was calculated for trans-[Pt(Cl)(PHCy2)2{P(O)Cy2}] (4) where intramolecular PO···H−P interactions act as a molecular brake at room temperature. Single-crystal X-ray diffraction confirms the presence of both intra and intermolecular PO···H interactions in solid 4. In the case of [Pt(Cl)(PHCy2)3]Cl, multinuclear NMR analysis indicates the presence of a P−H···Cl- interaction in aromatic or halogenated solvents which could have also a minor effect on the rotational barrier around the P(X)−Pt bond.