Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, Universidad de Zaragoza-C.S.I.C., E-50009 Zaragoza, Spain.
Inorg Chem. 2013 May 6;52(9):5493-506. doi: 10.1021/ic4004005. Epub 2013 Apr 18.
The dinuclear anionic complexes [NBu4][(RF)2M(II)(μ-PPh2)2M'(II)(N(^)O)] (RF = C6F5. N(^)O = 8-hydroxyquinolinate, hq; M = M' = Pt 1; Pd 2; M = Pt, M' = Pd, 3. N(^)O = o-picolinate, pic; M = Pt, M' = Pt, 4; Pd, 5) are synthesized from the tetranuclear [NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-Cl)}2] by the elimination of the bridging Cl as AgCl in acetone, and coordination of the corresponding N,O-donor ligand (1, 4, and 5) or connecting the fragments "cis-(RF)2M(μ-PPh2)2" and "M'(N(^)O)" (2 and 3). The electrochemical oxidation of the anionic complexes 1-5 occurring under HRMS(+) conditions gave the cations (RF)2M(μ-PPh2)2M'(N(^)O), presumably endowed with a M(III),M'(III) core. The oxidative addition of I2 to the 8-hydroxyquinolinate complexes 1-3 triggers a reductive coupling between a PPh2 bridging ligand and the N,O-donor chelate ligand with formation of a P-O bond and ends up in complexes of platinum(II) or palladium(II) of formula [(RF)2M(II)(μ-I)(μ-PPh2)M'(II)(P,N-PPh2hq)], M = M' = Pt 7, Pd 8; M = Pt, M' = Pd, 9. Complexes 7-9 show a new Ph2P-OC9H6N (Ph2P-hq) ligand bonded to the metal center in a P,N-chelate mode. Analogously, the addition of I2 to solutions of the o-picolinate complexes 4 and 5 causes the reductive coupling between a PPh2 bridging ligand and the starting N,O-donor chelate ligand with formation of a P-O bond, forming Ph2P-OC6H4NO (Ph2P-pic). In these cases, the isolated derivatives [NBu4][(Ph2P-pic)(RF)Pt(II)(μ-I)(μ-PPh2)M(II)(RF)I] (M = Pt 10, Pd 11) are anionic, as a consequence of the coordination of the resulting new phosphane ligand (Ph2P-pic) as monodentate P-donor, and a terminal iodo group to the M atom. The oxidative addition of I2 to [NBu4][(RF)2Pt(II)(μ-PPh2)2Pt(II)(acac)] (6) (acac = acetylacetonate) also results in a reductive coupling between the diphenylphosphanido and the acetylacetonate ligand with formation of a P-O bond and synthesis of the complex [NBu4][(RF)2Pt(II)(μ-I)(μ-PPh2)Pt(II)(Ph2P-acac)I] (12). The transformations of the starting complexes into the products containing the P-O ligands passes through mixed valence M(II),M'(IV) intermediates which were detected, for M = M' = Pt, by spectroscopic and spectrometric measurements.
双核阴离子配合物 [NBu4][(RF)2M(II)(μ-PPh2)2M'(II)(N(^)O)]（RF = C6F5，N(^)O = 8-羟基喹啉酸盐，hq；M = M' = Pt 1；Pd 2；M = Pt，M' = Pd，3；N(^)O = 邻-吡啶甲酸，pic；M = Pt，M' = Pt，4；Pd，5）是通过消除桥接 Cl 作为 AgCl 在丙酮中从四核 [NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-Cl)}2]合成的，并配位相应的 N,O-供体配体（1、4 和 5）或连接“顺式-(RF)2M(μ-PPh2)2”（2 和 3）片段。在 HRMS(+)条件下，阴离子配合物 1-5 的电化学氧化产生了 (RF)2M(μ-PPh2)2M'(N(^)O)阳离子，推测其具有 M(III),M'(III)核。碘 2 对 8-羟基喹啉酸盐配合物 1-3 的氧化加成引发了 PPh2 桥连配体和 N,O-供体螯合配体之间的还原偶联，形成 P-O 键，并最终生成式为 [(RF)2M(II)(μ-I)(μ-PPh2)M'(II)(P,N-PPh2hq)]，M = M' = Pt 7，Pd 8；M = Pt，M' = Pd，9 的铂(II)或钯(II)配合物。配合物 7-9 显示出一种新的 Ph2P-OC9H6N（Ph2P-hq）配体以 P,N-螯合模式键合到金属中心。类似地，向邻-吡啶甲酸配合物 4 和 5 的溶液中加入 I2 会导致 PPh2 桥连配体和起始 N,O-供体螯合配体之间发生还原偶联，形成 P-O 键，形成 Ph2P-OC6H4NO（Ph2P-pic）。在这些情况下，分离得到的衍生物 [NBu4][(Ph2P-pic)(RF)Pt(II)(μ-I)(μ-PPh2)M(II)(RF)I]（M = Pt 10，Pd 11）是阴离子的，这是由于新膦配体（Ph2P-pic）作为单齿 P-供体与生成的配位以及末端碘基团与 M 原子配位的结果。碘 2 对 [NBu4][(RF)2Pt(II)(μ-PPh2)2Pt(II)(acac)]（6）（acac = 乙酰丙酮）的氧化加成也导致二苯基膦和乙酰丙酮配体之间发生还原偶联，形成 P-O 键，并合成了配合物 [NBu4][(RF)2Pt(II)(μ-I)(μ-PPh2)Pt(II)(Ph2P-acac)I]（12）。起始配合物转化为含有 P-O 配体的产物的过程经过了混合价态 M(II),M'(IV)中间体的检测，对于 M = M' = Pt，通过光谱和光谱测量进行了检测。
