Unusual Phosphoryl Donor Properties of OP(MeNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N

1998-09-05T00:00:00Z (GMT) by Xiao-Dong Liu John G. Verkade
The title compound (<b>4</b>) in which transannular bridgehead−bridgehead bonding is absent, reacts with phosphoryl and silyl chlorides to give the isolable salts [ZOP(MeNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N]Cl where Z = Ph<sub>2</sub>P(O), <b>6</b>(Cl); PhP(O)Cl, <b>7</b>(Cl); <sup>1</sup>/<sub>2</sub>PhP(O), <b>8</b>(Cl); MeSiCl<sub>2</sub>, <b>14</b>(Cl); and SiCl<sub>3</sub>, <b>15</b>(Cl). Spectroscopic evidence for [ROP(MeNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N]<sup>+</sup> cations, where R = H, <b>16</b>; Me, <b>17</b>; Et, <b>18</b>, and the isolation of the regioisomeric cations [OP(MeNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>NR]<sup>+</sup> (R = Me, <b>19</b>; Et, <b>20</b>; <i>n</i>-Pr, <b>21</b>; <i>n</i>-Bu, <b>22</b>) as their iodide salts is also reported. In the presence of Cl<sub>3</sub>PO, PCl<sub>5</sub>, or SOCl<sub>2</sub>, <b>4</b> gives the [ClP(MeNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N]<sup>+</sup> cation (<b>26</b>) which is also formed when P(MeNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N is oxidized with C<sub>2</sub>Cl<sub>6</sub>. The more sterically hindered analogue of <b>4</b>, namely OP(<i>i</i>-PrNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N (<b>28</b>) (whose synthesis is reported herein), reacts with MeI and EtI to afford the isolable salts [OP(<i>i</i>-PrNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>NR]I [R = Me, <b>29</b>(I); Et, <b>30</b>(I)]. Cations <b>29</b> and <b>30</b> display <sup>1</sup>H and <sup>13</sup>C NMR spectra at room temperature that are consistent with a quaternization-induced rigidity of the cage that renders the (CH<sub>3</sub>)<sub>2</sub>CH methyl groups inequivalent on the NMR time scale. Acyclic OP(NMe<sub>2</sub>)<sub>3</sub> reacts with [R<sub>3</sub>O]BF<sub>4</sub> (R = Me, Et) giving the corresponding isolated salts [MeOP(NMe<sub>2</sub>)<sub>3</sub>]BF<sub>4</sub> and [EtOP(NMe<sub>2</sub>)<sub>3</sub>]BF<sub>4</sub>. Reaction of HCl with OP(NMe<sub>2</sub>)<sub>3</sub> afforded sublimable (Me<sub>2</sub>N)<sub>3</sub>PO·HCl which represents the first protonated phosphoryl species structured by X-ray crystallography. The transannular bond lengths in <b>6</b>(Cl) and <b>26</b>(PCl<sub>6</sub>) [1.948(5) Å and 1.934(8) Å, respectively] are within experimental error of the corresponding link in the [HP(MeNCH<sub>2</sub>CH<sub>2</sub>)<sub>3</sub>N]<sup>+</sup> cation [1.967(8) Å].