Application of the NOE experiment to the analysis of boron hydride derivatives: confirming the assignments of the pseudocloso-complex [1,2-Ph 2-3-{Cp*}-3,1,2-IrC 2B 9H 9] (Cp*=η 5-C 5Me 5) and the closo-compounds 1-Ph-1,2-C 2B 10H 11 and 1-Ph-2-Me-1,2-C 2B 10H 10

Abstract

The NOE experiment is demonstrated here as a viable tool in the NMR analyses of substituted borane and heteroborane compounds. We demonstrate that the saturation of 1H NMR signals assigned to a substituent ligand can give rise to enhancements of signals arising from B–H’s within a borane cage. These enhancements, though small (ca. 1–2%), are clearly detectable and have been used to confirm assignments for the pseudocloso-complex [1,2-Ph 2-3-{Cp*}-3,1,2-IrC 2B 9H 9] (Cp*=η 5-C 5Me 5), the mono-substituted closo-carbaborane 1-Ph-1,2-C 2B 10H 11 and the di-substituted closo-carbaborane 1-Ph-2-Me-1,2-C 2B 10H 10. We compare the results of applying three alternative experimental NOE procedures to these problems, namely phase sensitive 2D NOESY, 1D truncated driven NOE and 1D DPFGSE-NOE. The differences between the quality and relevance of these procedures to the study of borane and heteroborane derivatives are discussed.