COORDINATION CHEMISTRY OF HIGHER OXIDATION-STATES .38. SYNTHESIS, SPECTROSCOPIC AND ELECTROCHEMICAL STUDIES OF SOME TRANS-DIHALOGENOOSMIUM COMPLEXES - CRYSTAL-STRUCTURE OF TRANS-[OS(PME3)4CL2]BF4
COORDINATION CHEMISTRY OF HIGHER OXIDATION-STATES .38. SYNTHESIS, SPECTROSCOPIC AND ELECTROCHEMICAL STUDIES OF SOME TRANS-DIHALOGENOOSMIUM COMPLEXES - CRYSTAL-STRUCTURE OF TRANS-[OS(PME3)4CL2]BF4
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DOI：
10.1039/dt9910002777
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发表时间：
1991-10-01
期刊：
影响因子：
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通讯作者：
WEBSTER, M
中科院分区：
文献类型：
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作者：
CHAMPNESS, NR;LEVASON, W;WEBSTER, M
由[Os(PPh_3)_3X_2]和PMe_3得到了反式[Os(PPh_3)_4X_2]和反式[OsL_4X_2][L=PMe_2Ph、AsMe_3、Sb_Ph_3或吡啶(Py)]配合物。在空气中氧化生成反式[OsL4X2]BF4(L=PMe3或AsMe3)，而生成反式[OsL4X2]BF4(L=PMe2Ph，SbPh或Py)和顺式[Os(PMe2Ph)4Cl2]BF4需要硝酸作为氧化剂。利用浓硝酸在溶液中生成反式[OsL4X2]2+(L=PMe3、Ame2Ph或AsMe3)，但尚未分离到它们。用红外光谱、紫外-可见光谱和核磁共振光谱对配合物进行了表征，并用循环伏安法探讨了立体化学和L、X对Os(II)-Os(III)和Os(III)-Os(IV)氧化还原电位的影响。测定了反式[Os(PMe3)4Cl]BF4的晶体结构：正交晶系，空间群Fddd，a=8.104(4)，b=32.195(11)，c=38.540(9)埃，Z=16。该阳离子具有Os-P 2.419(5)和2.398(5)埃，Os-Cl 2.352(4)埃，并且由于空间相互作用使OsP4单元偏离平面度。没有证据表明Mer-[IrL3Cl3](L=PEtPh2，AsMe2Ph，SbPh3或Sme2)可以被化学或电化学氧化成稳定的Ir(IV)阳离子。
The complexes trans-[Os(PMe3)4X2] (X = Cl or Br) have been obtained from [Os(PPh3)3X2] and PMe3, and trans-[OsL4X2] [L = PMe2Ph, AsMe3, SbPh3 or pyridine (py)] by reduction of appropriate osmium(III) complexes in the presence of L. The complexes cis-[Os(PR3)4X2] are formed by isomerisation of the trans analogues in chlorinated solvents, and in other ways. Air oxidation of the osmium(II) complexes gives trans-[OsL4X2]BF4 (L = PMe3 or AsMe3), but formation of trans-[OsL4X2]BF4 (L = PMe2Ph, SbPh3 or py) and cis-[Os(PMe2Ph)4Cl2]BF4 requires HNO3 as oxidant. Use of concentrated HNO3 gives trans-[OsL4X2]2+ (L = PMe3, AMe2Ph or AsMe3) in solution, but these have not been isolated. The complexes have been characterised by IR, UV-VIS, and NMR spectroscopies, and the effect of stereochemistry and L and X upon the Os(II)-Os(III) and Os(III)-Os(IV) redox potentials probed by cyclic voltammetry. The crystal structure of trans-[Os(PMe3)4Cl]BF4 has been determined: orthorhombic, space group Fddd, a = 8.104(4), b = 32.195(11), c = 38.540(9) angstrom, and Z = 16. The cation has Os-P 2.419(5) and 2.398(5) angstrom and Os-Cl 2.352(4) angstrom, and shows deviations of the OsP4 unit from planarity due to steric interactions. There is no evidence that mer-[IrL3Cl3] (L = PEtPh2, AsMe2Ph, SbPh3 or SME2) can be oxidised either chemically or electrochemically to stable iridium (IV) cations.