Distortional Effects of Noncovalent Interactions in the Crystal Lattice of a Cp*Ir(III) Acylhydroxamic Acid Complex: A Joint Experimental–Computational Study

Abstract

[Cp*Ir­(μ-OH)₃IrCp*]­OH reacts with PhCONHOH to give [Cp*Ir­(η²-ONCOPh)], in which the doubly deprotonated −NHOH unit binds side-on via N and O, an otherwise unrecorded binding mode. The X-ray structure shows pyramidalization at Ir together with secondary bonding between the carbonyl oxygen and Ir (<i>d</i>_Ir···O = 2.873(8) Å). The related <i>o</i>-hydroxyphenyl­hydroxamic acid gives a conventional chelate structure in which both sp³ O atoms are bound in deprotonated form. In contrast, PhSO₂NHOH reacts with S–N cleavage to give the nitrosyl, [Cp*Ir­(NO)­(SO₂Ph)]. A detailed computational analysis identifies noncovalent interactions in the crystal lattice (crystal-packing effects) as responsible for the distortion in [Cp*Ir­(η²-ONCOPh)]