Department of Chemistry, 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.
Inorg Chem. 2011 Jun 6;50(11):5223-33. doi: 10.1021/ic2005248. Epub 2011 May 10.
The syntheses and reaction chemistry of two electron mixed-valence diphosphazane-bridged dirhodium and diiridium complexes M(2)(0,II)(tfepma)(2)(CN(t)Bu)(2)Cl(2) [M = Rh (1), Ir (2); tfepma = MeNP(OCH(2)CF(3))(2), CN(t)Bu = tert-butyl isocyanide] are described. 1 and 2 undergo addition and two-electron oxidation and reduction chemistries. In the presence of CN(t)Bu, the addition product with the stoichiometry M(2)(0,II)(tfepma)(2)(CN(t)Bu)(3)Cl(2) [M = Rh (3), Ir (3)] is generated; in the presence of 1 equiv of CN(t)Bu and 2 equiv of bis(pentamethyl-cyclopentadienyl)cobalt(II), 1 and 2 are reduced to furnish M(2)(0,0)(tfepma)(2)(CN(t)Bu)(3) [M = Rh (5), Ir (6)], which feature both four- and five-coordinate M(0) centers. Complexes 1, 2, 5, and 6 all possess coordinatively unsaturated square planar M(0) centers that are reactive: (1) 2 reacts with PhICl(2) to produce Ir(2)(II,II)(tfepma)(2)(CN(t)Bu)(2)Cl(4) (7); (2) protonation of 2 with HX yields Ir(2)(II,II)(tfepma)(2)(CN(t)Bu)(2)Cl(2)HX [X = Cl(-) (8), OTs(-) (9)]; (3) protonation of 5 with HOTs produces Rh(2)(I,I)(tfepma)(2)(CN(t)Bu)(3)(μ-H); and (4) the reversible hydrogenation of 2 proceeds smoothly, furnishing the cis-dihydride complex Ir(2)(II,II)(tfepma)(2)(CN(t)Bu)(2)(H)(2)Cl(2) (11). Substitution of tfepma in 2 with bis(diphenylphsophino)methane (dppm) yields the orthometalated complex Ir(2)(II,II)(dppm)(PPh(o-C(6)H(4))CH(2)PPh(2))(CN(t)Bu)(2)Cl(2)H (12). The X-ray crystal structures of 11 compounds are presented and discussed, and spectroscopic characterization by multinuclear and variable temperature NMR provides details about solution structures and in some cases the formation of isomeric products. The electronic spectra of the new complexes are also described briefly, with absorption and emission features derived from the bimetallic core.
本文描述了两种电子混合价二膦嗪桥联二铑和二铱配合物 M(2)(0,II)(tfepma)(2)(CN(t)Bu)(2)Cl(2) [M = Rh (1), Ir (2); tfepma = MeNP(OCH(2)CF(3))(2), CN(t)Bu = 叔丁基异氰化物]的合成和反应化学。1 和 2 经历加成和两电子氧化还原化学。在 CN(t)Bu 的存在下，生成具有化学计量比 M(2)(0,II)(tfepma)(2)(CN(t)Bu)(3)Cl(2) [M = Rh (3), Ir (3)]的加成产物；在 1 当量 CN(t)Bu 和 2 当量双(五甲基环戊二烯基)钴(II)的存在下，1 和 2 被还原为 M(2)(0,0)(tfepma)(2)(CN(t)Bu)(3) [M = Rh (5), Ir (6)]，其特征为四配位和五配位 M(0)中心。配合物 1、2、5 和 6 均具有配位不饱和的平面正方形 M(0)中心，具有反应性：(1) 2 与 PhICl(2)反应生成 Ir(2)(II,II)(tfepma)(2)(CN(t)Bu)(2)Cl(4) (7)；(2) 2 用 HX 质子化生成 Ir(2)(II,II)(tfepma)(2)(CN(t)Bu)(2)Cl(2)HX [X = Cl(-) (8), OTs(-) (9)]；(3) 5 用 HOTs 质子化生成 Rh(2)(I,I)(tfepma)(2)(CN(t)Bu)(3)(μ-H)；(4) 2 的可逆氢化顺利进行，生成顺二氢化物配合物 Ir(2)(II,II)(tfepma)(2)(CN(t)Bu)(2)(H)(2)Cl(2) (11)。在 2 中用双(二苯基膦基)甲烷(dppm)取代 tfepma 生成对位金属化配合物 Ir(2)(II,II)(dppm)(PPh(o-C(6)H(4))CH(2)PPh(2))(CN(t)Bu)(2)Cl(2)H (12)。介绍并讨论了 11 种化合物的 X 射线晶体结构，通过多核和变温 NMR 进行的光谱表征提供了有关溶液结构的详细信息，在某些情况下还提供了异构产物的形成情况。简要描述了新配合物的电子光谱，吸收和发射特征源自双金属核。
