Studies of a Reluctant Ligand. An X-ray Crystallographic and NMR Spectroscopic Analysis of (OC)<sub>5</sub>W(η<sup>1</sup>-PPh<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>) and Its (OC)<sub>5</sub>W(μ-PPh<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>)W(CO)<sub>5</sub> Derivative John William Benson Richard L. Keiter Ellen A. Keiter Arnold L. Rheingold Glenn P. A. Yap Vera V. Mainz 10.1021/om980288p.s002 https://acs.figshare.com/articles/journal_contribution/Studies_of_a_Reluctant_Ligand_An_X-ray_Crystallographic_and_NMR_Spectroscopic_Analysis_of_OC_sub_5_sub_W_sup_1_sup_-PPh_sub_2_sub_CH_sub_2_sub_PPh_sub_2_sub_and_Its_OC_sub_5_sub_W_-PPh_sub_2_sub_CH_sub_2_sub_PPh_sub_2_sub_W_CO_sub_5_sub_Derivative/3782424 Tungsten pentacarbonyl complexes, (OC)<sub>5</sub>W(η<sup>1</sup>-PPh<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>) (<b>1</b>) and (OC)<sub>5</sub>W(μ-PPh<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>)W(CO)<sub>5</sub> (<b>2</b>), have been synthesized from (OC)<sub>5</sub>WNH<sub>2</sub>Ph and Ph<sub>2</sub>PCH<sub>2</sub>PPh<sub>2</sub> in toluene, and their solid-state structures have been determined by single-crystal X-ray diffraction. The lone pair of electrons on the dangling phosphine in <b>1</b> is oriented toward the W(CO)<sub>5</sub> unit in the solid state, and <sup>13</sup>C{<sup>1</sup>H} and <sup>31</sup>P{<sup>1</sup>H} NMR data suggest that this conformation may also be dominant in solution. Phosphorus−phosphorus coupling in <b>1</b> (<sup>2</sup><i>J</i><sub>PP</sub> = 106 Hz) is significantly larger than in any previously reported complex of Ph<sub>2</sub>PCH<sub>2</sub>PPh<sub>2</sub> and is highly dependent on changes in temperature and solvent. Also observed is an unprecedented long-range phosphorus−carbon coupling (<sup>4</sup><i>J</i><sub>PC</sub> = 3.0 Hz) between the dangling phosphine and the equatorial carbonyl carbons of <b>1</b>, which is attributed to a conformational and/or “through-space” enhancement. On the basis of the structural and spectral data, the reluctance of <b>1</b> to react with (OC)<sub>5</sub>WNH<sub>2</sub>Ph to give <b>2</b> is explained in terms of the substantial ligand conformation change required. 1998-08-19 00:00:00 Ph 2 PCH 2 PPh 2 OC ligand conformation change 2 J PP NMR Spectroscopic Analysis 5 WNH 2 Ph 4 J PC 1 H Tungsten pentacarbonyl complexes PPh 2 CH 2 PPh 2