10.1021/om030411z.s001 Houston Byrd Houston Byrd Jeremiah D. Harden Jeremiah D. Harden Jennifer M. Butler Jennifer M. Butler Michael J. Jablonsky Michael J. Jablonsky Gary M. Gray Gary M. Gray Nucleophilic Displacement Reactions of <i>cis</i>-Bis((2,2‘-biphenylylene)phosphochloridite ester)tetracarbonylmolybdenum(0). The First Example of an Unusual Hydrolysis Reaction Yielding Unsymmetrically Substituted Products American Chemical Society 2003 nucleophilic displacement reactions ligand RX NMR studies Unusual Hydrolysis Reaction Yielding Unsymmetrically Substituted Products Ligands diastereomer solution dioxaphosphepin PO Mo conformation Pr n H 2 nucleophilic substitution reactions NH chloride disubstituted complexes cis XR hydrolysis SC bulkier biaryl groups OMe PXR nucleophile Nucleophilic Displacement Reactions NPr n 2003-10-13 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Nucleophilic_Displacement_Reactions_of_i_cis_i_Bis_2_2_biphenylylene_phosphochloridite_ester_tetracarbonylmolybdenum_0_The_First_Example_of_an_Unusual_Hydrolysis_Reaction_Yielding_Unsymmetrically_Substituted_Products/3361561 Ligands containing groups derived from bis(aryl)diols are widely used in asymmetric catalysis; however, few studies of the conformations of these ligands in transition-metal complexes have been reported. In this paper, the nucleophilic displacement reactions of <i>cis</i>-Mo(CO)<sub>4</sub>(2,2‘-C<sub>12</sub>H<sub>8</sub>O<sub>2</sub>PCl)<sub>2</sub> (<b>1</b>) have been used to prepare a variety of complexes with [1,3,2]dioxaphosphepin ligands, and the conformations of these ligands have been studied by NMR spectroscopy and X-ray crystallography. The nucleophilic substitution reactions yield both the expected disubstituted complexes <i>cis</i>-Mo(CO)<sub>4</sub>(2,2‘-C<sub>12</sub>H<sub>8</sub>O<sub>2</sub>PXR)<sub>2</sub> (XR = NPr<sup>n</sup> (<b>2</b>), OMe (<b>4</b>), SC<sub>6</sub>H<sub>4</sub>-4-Me (<b>6</b>)) and the unexpected hydrolysis products [R‘<sub>3</sub>NH][<i>cis</i>-Mo(CO)<sub>4</sub>(2,2‘-C<sub>12</sub>H<sub>8</sub>O<sub>2</sub>PO)(2,2‘-C<sub>12</sub>H<sub>8</sub>O<sub>2</sub>PXR)] (R‘<sub>3</sub> = Pr<sup>n</sup>H<sub>2</sub>, XR = NPr<sup>n</sup>, <b>3</b>; R‘<sub>3</sub> = Et<sub>3</sub>; XR = OMe, <b>5</b>). NMR studies have demonstrated that the hydrolysis product is the major product when more than a minute amount of water is present, even in the presence of a large excess of the nucleophiles. This reaction is complete in approximately 90 min at 25 °C. A very surprising feature of this reaction is that substitution of one chloride in <b>1 </b>by the RX<sup>-</sup> nucleophile greatly enhances the rate of substitution of the second chloride either by water or by another RX<sup>-</sup> nucleophile. NMR studies of the [1,3,2]dioxaphosphepin complexes in chloroform-<i>d</i> solution suggest that the <i>R</i>* and <i>S*</i> enantiomers of the ligands interconvert via a low-energy pathway. Crystal structures of the complexes demonstrate that both the <i>R</i>*<i>S</i>* diastereomer (<b>1</b>) and racemic mixtures of the <i>R</i>*<i>R</i>* and <i>S</i>*<i>S</i>* diastereomers (<b>2</b>−<b>4</b>) are observed in the solid state. These results suggest that bulkier biaryl groups are needed to prevent the racemization of the [1,3,2]dioxaphosphepin ligands in solution.