Department of Chemistry and Laboratory for Research on the Structure of Matter, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
J Am Chem Soc. 2010 Mar 31;132(12):4107-9. doi: 10.1021/ja100894h.
Formally zerovalent, dinitrogen-bridged ruthenium complex, {[N(3)(Xyl)]Ru}(2)(mu-eta(1):eta(1)-N(2)) (1), where [N(3)(Xyl)] = 2,6-(XylN horizontal lineCMe)(2)C(5)H(3)N, reacts with excess H(2) to give the binuclear hydride species, {[N(3)]Ru(H)}(2)(mu-eta(1):eta(1)-N(2)) (2) bearing a single hydrogen per ruthenium. Complex 2 is an unusual example of a structurally characterized paramagnetic transition metal hydride, and the first such example for ruthenium. Structural data and DFT calculations suggest unpaired electron density is strongly delocalized onto the non-innocent [N(3)] ligand, with a relatively small degree of the metalloradical character implied by the Ru(I) formal oxidation state, and that the N(3)/Ru(II) formalism may be more informative. Consistent with an effective oxidation state greater than Ru(I), further reaction of 2 with excess H(2) to give metal dihydride species ([N(3)]RuH(2)(L)) is not observed. The magnetic moment of 2 (3.50 mu(B)) in solution is consistent with one unpaired electron per [N(3)]Ru moiety; however, 2 is diamagnetic in the solid due to close (3.26 A) head-to-tail contact between Ru pyridine planes of neighboring molecules. Although the geometry is reminiscent of the weak "pi-stacking" observed for closed-shell aromatic ring systems, DFT calculations indicate the structure and associated spin pairing result from in-phase overlap of the delocalized SOMOs on neighboring molecules-that is the interaction is best viewed as a weak covalent bond delocalized over 22 atoms.
形式上零价、桥联双氮的钌配合物，{[N(3)(Xyl)]Ru}(2)(mu-eta(1)：eta(1)-N(2))(1)，其中[N(3)(Xyl)]=2,6-(XylN 水平线 CMe)(2)C(5)H(3)N，与过量的 H(2)反应生成双核氢化物物种，{[N(3)]Ru(H)}(2)(mu-eta(1)：eta(1)-N(2))(2)，每个钌原子上带有一个氢。配合物 2 是结构表征的顺磁性过渡金属氢化物的一个不寻常例子，也是第一个这样的钌的例子。结构数据和 DFT 计算表明，不成对电子密度强烈离域到非配位的[N(3)]配体上，具有相对较小的金属自由基特征，暗示 Ru(I)形式氧化态，并且N(3)/Ru(II)形式可能更具信息性。与有效氧化态大于 Ru(I)一致，进一步与过量 H(2)反应生成金属二氢化物物种([N(3)]RuH(2)(L))没有观察到。2 在溶液中的磁矩(3.50 mu(B))与每个[N(3)]Ru 部分的一个未成对电子一致；然而，由于相邻分子的 Ru 吡啶平面之间的紧密(3.26 A)头尾接触，2 在固态中是抗磁性的。尽管几何形状类似于闭壳芳香环系统中观察到的弱“pi 堆积”，但 DFT 计算表明，结构和相关的自旋配对结果来自相邻分子上离域 SOMO 的同相重叠，即这种相互作用最好被视为在 22 个原子上离域的弱共价键。
