10.1021/om980288p.s002 John William Benson John William Benson Richard L. Keiter Richard L. Keiter Ellen A. Keiter Ellen A. Keiter Arnold L. Rheingold Arnold L. Rheingold Glenn P. A. Yap Glenn P. A. Yap Vera V. Mainz Vera V. Mainz 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 American Chemical Society 1998 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 1998-08-19 00:00:00 Journal contribution 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.