Miller Warren K, Gilbertson John D, Leiva-Paredes Carmen, Bernatis Paul R, Weakley Timothy J R, Lyon David K, Tyler David R
Bend Research, Inc., 64550 Research Road, Bend, OR 97701, USA.
Inorg Chem. 2002 Oct 21;41(21):5453-65. doi: 10.1021/ic025774q.
The reactions of the water-soluble chelating phosphines 1,2-bis(bis(hydroxyalkyl)phosphino)ethane (alkyl = n-propyl, DHPrPE; n-butyl, DHBuPE; n-pentyl, DHPePE) with FeCl(2).4H(2)O and FeSO(4).7H(2)O were studied as routes to water-soluble complexes that will bind small molecules, dinitrogen in particular. The products that form and their stereochemistry depend on the solvent, the counteranion, and the alkyl chain length on the phosphine. In alcoholic solvents, the reaction of FeCl(2).4H(2)O with 2 equiv of DHBuPE or DHPePE gave trans-Fe(L(2))(2)Cl(2). The analogous reactions in water with DHBuPE and DHPePE gave only cis products, and the reaction of FeSO(4).7H(2)O with any of the phosphines gave only cis-Fe(L(2))(2)SO(4). These results are interpreted as follows. The trans stereochemistry of the products from the reactions of FeCl(2).4H(2)O in alcohols is suggested to be the consequence of the trans geometry of the Fe(H(2)O)(4)Cl(2) complex, i.e., substitution of the water molecules by the phosphines retains the geometry of the starting material. The formation of cis-Fe(DHPrPE)(2)Cl(2) is an exception to this result because the coordination of two -OH groups forms two six-membered rings, as shown in the X-ray structure of the molecule. DHBuPE and DHPePE reacted with FeSO(4).7H(2)O in water to initially yield cis-Fe(P(2))(2)SO(4) compounds, but subsequent substitution reactions occurred over several hours to give sequentially trans-Fe(DHBuPE)(2)(H(2)O)(SO(4)) and then trans-[Fe(DHBuPE)(2)(H(2)O)(2)]SO(4). The rate constants and activation reactions for these aquation reactions were determined and are consistent with dissociatively activated mechanisms. The cis- and trans-Fe(L(2))(2)X (X = (Cl)(2) or SO(4)) complexes react with N(2), CO, and CH(3)CN to yield trans complexes with bound N(2), CO, or CH(3)CN. The crystal structures of the cis-Fe(DHPrPE)(2)SO(4), trans-Fe(DHPrPE)(2)(CO)SO(4), trans-Fe(DHBuPE)(2)Cl(2), trans-[Fe(DHBuPE)(2)(CO)(Cl)][B(C(6)H(5))(4)], trans-Fe(DMeOPrPE)(2)Cl(2), trans-Fe(DMeOPrPE)(2)Br(2), and trans-[Fe(DHBuPE)(2)Cl(2)]Cl complexes are reported. As expected from using water-soluble phosphines, the complexes reported herein are water soluble (generally greater than 0.5 M at 23 degrees C).
研究了水溶性螯合膦1,2 - 双（双（羟烷基）膦基）乙烷（烷基 = 正丙基，DHPrPE；正丁基，DHBuPE；正戊基，DHPePE）与FeCl₂·4H₂O和FeSO₄·7H₂O的反应，以此作为制备能结合小分子（特别是二氮）的水溶性配合物的途径。形成的产物及其立体化学取决于溶剂、抗衡阴离子以及膦上的烷基链长度。在醇类溶剂中，FeCl₂·4H₂O与2当量的DHBuPE或DHPePE反应生成反式Fe(L₂)₂Cl₂。在水中与DHBuPE和DHPePE进行的类似反应仅生成顺式产物，而FeSO₄·7H₂O与任何一种膦的反应仅生成顺式Fe(L₂)₂SO₄。这些结果的解释如下。FeCl₂·4H₂O在醇中反应产物的反式立体化学被认为是Fe(H₂O)₄Cl₂配合物反式几何构型的结果，即膦取代水分子保留了起始原料的几何构型。顺式Fe(DHPrPE)₂Cl₂的形成是此结果的一个例外，因为两个 -OH基团的配位形成了两个六元环，如该分子的X射线结构所示。DHBuPE和DHPePE在水中与FeSO₄·7H₂O反应最初生成顺式Fe(P₂)₂SO₄化合物，但随后的取代反应在数小时内发生，依次生成反式Fe(DHBuPE)₂(H₂O)(SO₄)，然后是反式[Fe(DHBuPE)₂(H₂O)₂]SO₄。测定了这些水合反应的速率常数和活化反应，它们与离解活化机制一致。顺式和反式Fe(L₂)₂X（X = (Cl)₂或SO₄）配合物与N₂、CO和CH₃CN反应生成带有结合的N₂、CO或CH₃CN的反式配合物。报道了顺式Fe(DHPrPE)₂SO₄、反式Fe(DHPrPE)₂(CO)SO₄、反式Fe(DHBuPE)₂Cl₂、反式[Fe(DHBuPE)₂(CO)(Cl)][B(C₆H₅)₄]、反式Fe(DMeOPrPE)₂Cl₂、反式Fe(DMeOPrPE)₂Br₂和反式[Fe(DHBuPE)₂Cl₂]Cl配合物的晶体结构。正如使用水溶性膦所预期的那样，本文报道的配合物是水溶性的（在23℃时通常大于0.5 M）。
