乙腈溶液中锇氮化合物电化学诱导桥氮偶联过程的原位FTIR反射光谱

采用原位红反射光谱（ｉｎ－ｓｉｔｕ－ＦＴＩＲＳ）结合紫外可见光谱（ＵＶ／Ｖｉｓ）和电化学徨伏安技术（ＣＶ）,研究了「Ｏｓ＾Ⅵ（Ｎ）（ＮＨ３）４」（ＣＦ３ＳＯ３）３的电化学诱导桥氮偶联过程。首次在Ｐｔ电极上检测到桥氮混合价锇物中「Ｏｓ－Ｎ≡Ｎ－ｏＳ」及其随电位的变化过程。在约２ｍ ｍｏｌ／Ｌ「Ｏｓ＾Ⅵ（Ｎ）（ＮＨ）」（ＣＦ要的乙腈溶液中,选取０．４－－１．０Ｖ电位区间１００ｍＶ／ｓ扫描速度,对Ｐｔ或     

MICROWAVE EFFECTS ON THE OXIDATIVE COUPLING OF MIETHANE OVER Li_2SO_4／BaCe_（0．93）La_（0．07）O_3

ＭＩＣＲＯＷＡＶＥＥＦＦＥＣＴＳＯＮＴＨＥＯＸＩＤＡＴＩＶＥＣＯＵＰＬＩＮＧＯＦＭＩＥＴＨＡＮＥＯＶＥＲＬｉ＿２ＳＯ＿４／ＢａＣｅ＿（０．９３）Ｌａ＿（０．０７）Ｏ＿３￥ＣｈａｎｇＬｉｎＣＨＥＮ；ＰｉｎＪｉｅＨＯＮＧ；ＳｈｕＳｈａｎＤＡＩ；Ｇｕａｎｇ...     

呋喃醛双缩二氨基硫脲腙的合成和结构测定

由ＣＳ＿２，Ｎ＿２Ｈ＿４和Ｃ＿４Ｈ＿３ＯＣＨＯ合成Ｃ＿（１１）Ｈ＿（１０）Ｎ＿４Ｏ＿２Ｓ·１／２ＤＭＦ，Ｍ＿ｒ＝２９８．７９，橙黄针状晶体，三斜晶系，空间群Ｐ１，ａ＝８．９１２（３），ｂ＝９．９８９（３），ｃ＝１６．１０７（４），ａ＝８３．６１８（６），β＝８７．１０５（５），γ＝８６．１１５（３）°，Ｖ＝１４２０．４，Ｚ＝４，Ｄ＿ｘ＝１．３９７ｇ／ｃｍ￣３，λ（ＭｏＫα）＝０．７１０７３，μ＝２．１７０ｃｍ￣（－１），Ｆ（０００）＝６１６。３２２６个可观察的独立反射（Ｉ＞３σ（Ｉ）使结构顺利解出，并精修到Ｒ＝０．０４８，△ρ＿（ｍａｘ）＝０．２８６。单晶体结构分析表明不对称单位含有二个非结晶学对称相关的独立分子和一个溶剂分子ＤＭＦ，通过ＤＭＦ中的ｏ原子和亚胺Ｈ形成Ｎ－Ｈ…Ｏ…Ｈ－Ｎ类型双氢键，使两个分立分子缔合一起而自成独立的结构单元。     

(η~2C_(60))Pt (PPh_3)_2 as the Catalystfor the Hydrosilylation of Olefins

（η￣２Ｃ＿（６０））Ｐｔ（ＰＰｈ＿３）＿２ａｓｔｈｅＣａｔａｌｙｓｔｆｏｒｔｈｅＨｙｄｒｏｓｉｌｙｌａｔｉｏｎｏｆＯｌｅｆｉｎｓＣＨＥＮＹｕａｎ－ｙｉｎ,ＳＨＥＮＧＲｏｎｇ－ｓｈｅｎａｎｄＬＩＵＹｉｎｇ（ＤｅｐａｒｔｒｎｅｎｔｏｆＣｈｅｒｎｉｓｔｒ...     

氯霉素在Pt/GC离子注入修饰电极上的伏安行为及其测定

氯霉素在浓度为０．１ ｍ ｏｌ／Ｌ 的ＮａＯＨ 溶液中,Ｐｔ／ＧＣ 离子注入修饰电极上有一还原峰,峰电位为 － ０．８０ Ｖ（ｖｓ．ＳＣＥ）,氯霉素的浓度在 １．０×１０－ ５～１．０×１０－ ３ ｍ ｏｌ／Ｌ 范围内与峰电流成正比。检出限为５．０×１０－ ６ ｍ ｏｌ／Ｌ。已用于氯霉素眼药水的测定。用线性扫描和循环伏安法研究体系的性质。实验表明,是注入的Ｐｔ催化了氯霉素的还原;体系属准可逆过程。     

氰尿酸镍的晶体结构

标题化合物Ｎｉ（Ｃ＿３Ｈ＿２Ｎ＿３Ｏ＿３）＿２（Ｈ２Ｏ）＿４属正交晶系，空间群为Ｆｍｍｍ（编号６９）。晶胞参数：ａ＝７．２８２（４），ｂ＝１２．０５７（２），ｃ＝１６．０７２（２），Ｖ＝１４１１（１），Ｄ＿ｃ＝１．８２ｇ／ｃｍ￣３，Ｚ＝４，Ｍ＿ｒ＝３８６．８９，λ（ＭｏＫα）＝０．７１０６９，μ＝１４．４３ｃｍ￣（－１），Ｆ（０００）＝７９２。最终偏离因子Ｒ＝０．０４５，Ｒ＿ｗ＝０．０６０。独立可观测点数（Ｉ≥３σ（Ｉ））为３８５个。在配合物中，镍离子与来自氰尿酸的两个氮原子和来自水分子的四个氧原子配位。     

μ－4，4＇－联吡啶桥联三核Cu（Ⅱ）配合物的合成和磁性

合成了３种以４，４＇－联吡啶为桥联配体的三核环状Ｃｕ（Ⅱ）配合物［Ｃｕ＿３（４，４＇－ｂｐｙ）＿３·（ｐｈｅｎ）＿３］（ＣｌＯ＿４）＿６·２Ｈ＿２Ｏ（１）、［Ｃｕ＿３（４，４＇－ｂｐｙ）＿３］（ｂｐｙ）＿３］（ＣｌＯ＿４）＿６·Ｈ＿２Ｏ（２）和［Ｃｕ＿３（４，４＇－ｂｐｙ）＿３·（ＮＯ＿２－ｐｈｅｎ）＿３］（ＣｌＯ＿４）＿６·６Ｈ＿２Ｏ（３）。经元素分析、电导、ＩＲ、电子光谱、ＥＳＲ、磁化率等方法进行了表征，推定该配合物具有以４，４＇－联吡啶为扩展桥的结构。利用Ｈｅｉｓｅｎｂｅｒｇ模型求得交换参数Ｊ值为－０．２３ｃｍ－１（１）和－０．９０ｃｍ－１（３），表明配合物中金属离子间仅有很弱的反铁磁交换作用．     

三羰基环戊二烯基钼负离子与1，3－二卤丙烷的反应

三羰基环戊二烯基钼负离子与１，３－二卤丙烷在一缩二乙二醇二甲醚介质中反应，生成环卡宾配合物ＣｐＭｏＸ（ＣＯ）＿２ＣＯ（ＣＨ＿２）＿２ＣＨ２（Ｘ＝Ｂｒ，Ｉ）．硅桥连双环戊二烯基三羰基钼负离子与１，３－二卤丙烷顺利地进行类似反应，生成相应的硅桥连双［环卡宾钼配合物］──Ｅ［Ｃ＿５Ｈ＿４ＭｏＸ（ＣＯ）＿２］ＣＯ（ＣＨ＿２）＿２ＣＨ＿２］＿２（Ｅ＝Ｍｅ＿２Ｓｉ，Ｍｅ２ＳｉＳｉＭｅ＿２，Ｍｅ２ＳｉＯＳｉＭｅ＿２）．化合物硅氧硅桥联二茂二钼环卡宾配合物１１的晶体结构经Ｘ射线衍射测定，晶体属三斜晶系，Ｐ１空间群，晶体学数据：ａ＝０．８１８８（１）ｎｍ，ｂ＝１．０４５（３）ｎｍ，ｃ＝２．３２５２（４）ｎｍ，α＝９４．１４（２）°，β＝９４．０９（１）°，γ＝１０２．４８（２）°，Ｖ＝１．９３０６ｎｍ￣３，Ｚ＝２，Ｄ＿ｃ＝１．８５４ｇ／ｃｍ￣３。     

铜（Ⅱ）－聚丙烯酰胺和铜（Ⅱ）－聚乙烯醇配位聚合物的配位数

配位聚合物ＰＡＡｍ－ＣｕＣｌ＿２和ｃｕＣｌ＿２·２Ｈ＿２Ｏ的Ｃｕ￣（２＋）２ｐＸＰＳ谱上都有Ｓｈａｋｅ－ｕｐ峰，其与各自的Ｃｕ￣（２＋）２ｐ３／２肩峰或主峰距离ΔＥｓ２或ΔＥｓ分别为８．７和８．６ｅＶ；但配位聚合物Ｃｕ（Ⅱ）－ＰＶＡ却无此峰．由此推定，前者的Ｃｕ￣（２＋）是以ｓｐ￣３杂化轨道接受ＰＡＡｍ４个链节单元Ｃ－Ｎ上Ｎ的孤对电子部分转移形成配位键；而Ｃｕ（Ⅱ）－ＰＶＡ配位聚合物中的Ｃｕ￣（２＋）却以ｄｓｐ￣２杂化轨道接受ＰＶＡ４个链节单元侧基Ｏ的孤对电子部分转移，产生配位键，即Ｃｕ￣（２＋）与ＰＡＡｍ或ＰＶＡ的链节单元配位比均是１：４，此结果与电导率法测定ＰＡＡｍ－ＣｕＣｌ＿２的配位比相同．     

Synthesis and Crystal Structural Characterization of （NH＿4）＿5H＿3Mn＿3V＿（12）O＿（40）·15H＿2O

ＳｙｎｔｈｅｓｉｓａｎｄＣｒｙｓｔａｌＳｔｒｕｃｔｕｒａｌＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆ（ＮＨ＿４）＿５Ｈ＿３Ｍｎ＿３Ｖ＿（１２）Ｏ＿（４０）·１５Ｈ＿２ＯＷＡＮＧＺｕｏ－Ｐｉｎｇ;ＬＩＵＪｉｎｇ－ｆｕａｎｄＷＡＮＧＥｎ－ｂｏ（Ｄｅｐａｔｍｅｎ...     

Binuclear (salen)osmium phosphinidine and phosphiniminato complexes

The preparation of a number of binuclear (salen)osmium phosphinidine and phosphiniminato complexes using various strategies are described. Treatment of [Os(VI)(N)(L(1))(sol)](X) (sol = H(2)O or MeOH) with PPh(3) affords an osmium(IV) phosphinidine complex [Os(IV){N(H)PPh(3)}(L(1))(OMe)](X) (X = PF(6)1a, ClO(4)1b). If the reaction is carried out in CH(2)Cl(2) in the presence of excess pyrazine the osmium(III) phosphinidine species [Os(III){N(H)PPh(3)}(L(1))(pz)](PF(6)) 2 can be generated. On the other hand, if the reaction is carried out in CH(2)Cl(2) in the presence of a small amount of H(2)O, a μ-oxo osmium(IV) phosphinidine complex is obtained, [(L(1)){PPh(3)N(H)}Os(IV)-O-Os(IV){N(H)PPh(3)}(L(1))](PF(6))(2)3. Furthermore, if the reaction of [Os(VI)(N)(L(1))(OH(2))]PF(6) with PPh(3) is done in the presence of 2, the μ-pyrazine species, [(L(1)){PPh(3)N(H)}Os(III)-pz-Os(III){N(H)PPh(3)}(L(1))](PF(6))(2)4 can be isolated. Novel binuclear osmium(IV) complexes can be prepared by the use of a diphosphine ligand to attack two Os(VI)≡N. Reaction of [Os(VI)(N)(L(1))(OH(2))](PF(6)) with PPh(2)-C≡C-PPh(2) or PPh(2)-(CH(2))(3)-PPh(2) in MeOH affords the binuclear complexes [(MeO)(L(1))Os(IV){N(H)PPh(2)-R-PPh(2)N(H)}Os(IV)(L(1))(OMe)](PF(6))(2) (R = C≡C 5, (CH(2))(3)6). Reaction of [Os(VI)(N)(L(2))Cl] with PPh(2)FcPPh(2) generates a novel trimetallic complex, [Cl(L(2))Os(IV){NPPh(2)-Fc-PPh(2)N}Os(IV)(L(2))Cl] 7. The structures of 1b, 2, 3, 4, 5 and 7 have been determined by X-ray crystallography.     

Iminic N-bound iminophosphorano versus nitrilic n-bound iminophosphorano Os(IV) complexes: a new double derivatization of the nitrido ligand

The reactions between trans-[Os(IV)(tpy)(Cl)(2)(NCN)] (1) and PPh(3) and between trans-[Os(IV)(tpy)(Cl)(2)(NPPh(3))](+) (2) and CN(-) provide new examples of double derivatization of the nitrido ligand in an Os(VI)-nitrido complex (Os(VI)N). The nitrilic N-bound product from the first reaction, trans-[Os(II)(tpy)(Cl)(2)(NCNPPh(3))] (3), is the coordination isomer of the first iminic N-bound product from the second reaction, trans-[Os(II)(tpy)(Cl)(2)(N(CN)(PPh(3)))] (4). In CH(3)CN at 45 degrees C, 4 undergoes isomerrization to 3 followed by solvolysis and release of (N-cyano)iminophosphorane, NCNPPh(3). These reactions demonstrate new double derivatization reactions of the nitrido ligand in Os(VI)N with its implied synthetic utility.     

C--N bond formation on addition of aryl carbanions to the electrophilic nitrido ligand in TpOs(N)Cl(2).

The osmium(VI) nitrido complex TpOs(N)Cl(2) (1) has been prepared from K[Os(N)O(3)] and KTp in aqueous ethanolic HCl. It reacts rapidly with PhMgCl and related reagents with transfer of a phenyl group to the nitrido ligand. This forms Os(IV) metalla-analido complexes, which are readily protonated to give the analido complex TpOs(NHPh)Cl(2) (4). The nitrido-phenyl derivatives TpOs(N)PhCl and TpOs(N)Ph(2) react more slowly with PhMgCl and are not competent intermediates for the reaction of 1 with PhMgCl. Reactions of 1 with alkyl- and arylboranes similarly result in transfer of one organic group to nitrogen, leading to isolable borylamido complexes such as TpOs[N(Ph)(BPh(2))]Cl(2) (11). This is an unprecedented insertion of a nitrido ligand into a boron--carbon bond. Hydrolysis of 11 gives 4. Mechanistic studies suggest that both the Grignard and borane reactions proceed by initial weak coordination of Mg or B to the nitrido ligand, followed by migration of the carbanion to nitrogen. The hydrocarbyl group does not go to osmium and then move to nitrogen--there is no change in the atoms bound to the osmium during the reactions. It is suggested that there may be a general preference for nucleophiles to add directly to the metal--ligand multiple bond rather than binding to the metal first and migrating. Ab initio calculations show that the unusual reactivity of 1 results from its accessible LUMO and LUMO + 1, which are the Os = N pi* orbitals. The bonding in 1 and its reactivity with organoboranes are reminiscent of CO.     

Formation of μ-dinitrogen (salen)osmium complexes via ligand-induced N···N coupling of (salen)osmium(VI) nitrides

Treatment of [N(n)Bu(4)][Os(VI)(N)Cl(4)] with a stoichiometric amount of H(2)L (L = N,N'-bis(salicylidene)-o-cyclohexylenediamine dianion) in the presence of PF(6)(-) or ClO(4)(-) in MeOH affords [Os(VI)(N)(L)(OH(2))](PF(6)) 1a and [Os(VI)(N)(L)(CH(3)OH)](ClO(4)) 1b, respectively. The structure of 1b has been determined by X-ray crystallography and the Os≡N bond distance is 1.627(3) ?. In the presence of a N-donor heterocyclic ligand in CH(3)CN, 1a reacts at room temperature to afford the mixed-valence μ-N(2) (salen)osmium species [(X)(L)Os(III)-N≡N-Os(II)(L)(X)](PF(6)), 2-14 (X = py 2; 4-Mepy 3; 4-(t)Bupy 4; pz 5; 3-Mepz 6; 3,5-Me(2)pz 7; Im 8; 1-MeIm 9; 2-MeIm 10; 4-MeIm 11; 1,2-Me(2)Im 12; 2-Meozl 13; 4-MeTz 14). These complexes are formed by ligand-induced N···N coupling of two [Os(VI)≡N](+) to give initially [Os(III)-N(2)-Os(III)](2+), which is then reduced to give the more stable mixed-valence species [Os(III)-N(2)-Os(II)](+). Cyclic voltammograms (CVs) of 2-14 show two reversible couples, attributed to Os(III,III)/Os(III,II) and Os(III,II)/Os(II,II). The large comproportionation constants (K(com)) of (5.36-82.3) × 10(13) indicate charge delocalization in these complexes. The structures of 3 and 14 have been determined by X-ray crystallography, the salen ligands are in uncommon cis-β configuration. Oxidations of 4 and 14 by [Cp(2)Fe](PF(6)) afford the symmetrical species [(X)(L)Os(III)-N≡N-Os(III)(L)(X)](PF(6))(2) (X = 4-(t)Bupy 15; 4-MeTz 16). These are the first stable μ-N(2) diosmium(III,III) complexes that have been characterized by X-ray crystallography.     

Oxidation of ammonia in osmium polypyridyl complexes

The oxidations of cis- and trans-[OsIII(tpy)(Cl)2(NH3)](PF6), cis-[OsII(bpy)2(Cl)(NH3)](PF6), and [OsII(typ)(bpy)(NH3)](PF6)2 have been studied by cyclic voltammetry and by controlled-potential electrolysis. In acetonitrile or in acidic, aqueous solution, oxidation is metal-based and reversible, but as the pH is increased, oxidation and proton loss from coordinated ammonia occurs. cis- and trans-[OsIII(tpy)(Cl)2(NH3)](PF6) are oxidized by four electrons to give the corresponding OsVI nitrido complexes, [OSVI(typ)(Cl)2(N)]+. Oxidation of [Os(typ)(bpy)(NH3)](PF6)2 occurs by six electrons to give [Os(tpy)(bpy)(NO)](PF6)3. Oxidation of cis-[OsII(bpy)2(Cl)(NH3)](PF6) at pH 9.0 gives cis-[OsII(bpy)2(Cl)(NO)](PF6)2 and the mixed-valence form of the mu-N2 dimer [cis-[Os(bpy)2(Cl)2[mu-N2)](PF6)3. With NH4+ added to the electrolyte, cis-[OsII(bpy)2(Cl)(N2)](PF6) is a coproduct. The results of pH-dependent cyclic voltammetry measurements suggest OsIV as a common intermediate in the oxidation of coordinated ammonia. For cis- and trans-[OsIII(tpy)(Cl)2(NH3)]+, OsIV is a discernible intermediate. It undergoes further pH-dependent oxidation to [OsVI(tpy)(Cl)2(N)]+. For [OsII(tpy)(bpy)(NH3)]2+, oxidation to OsIV is followed by hydration at the nitrogen atom and further oxidation to nitrosyl. For cis-[OsII(bpy)2(Cl)-(NH3)]+, oxidation to OsIV is followed by N-N coupling and further oxidation to [cis-[Os(bpy)2(Cl)2(mu-N2)]3+. At pH 9, N-N coupling is competitive with capture of OsIV by OH- and further oxidation, yielding cis-[OsII(bpy)2(Cl)(NO)]2+.     

Reaction of an osmium(VI) nitrido complex with cyanide: formation and reactivity of an osmium(III) hydrogen cyanamide complex

Reaction of [Os(VI)(N)(L(1))(Cl)(OH(2))] (1) with CN(-) under various conditions affords (PPh(4))[Os(VI)(N)(L(1))(CN)(Cl)] (2), (PPh(4))(2)[Os(VI)(N)(L(2))(CN)(2)] (3), and a novel hydrogen cyanamido complex, (PPh(4))(2)[Os(III){N(H)CN}(L(3))(CN)(3)] (4). Compound 4 reacts readily with both electrophiles and nucleophiles. Protonation and methylation of 4 produce (PPh(4))[Os(III)(NCNH(2))(L(3))(CN)(3)] (5) and (PPh(4))[Os(III)(NCNMe(2))(L(3))(CN)(3)] (6), respectively. Nucleophilic addition of NH(3), ethylamine, and diethylamine readily occur at the C atom of the hydrogen cyanamide ligand of 4 to produce osmium guanidine complexes with the general formula [Os(III){N(H)C(NH(2))NR(1)R(2)}(L(3))(CN)(3)](-) , which have been isolated as PPh(4) salts (R(1) = R(2) = H (7); R(1) = H, R(2) = CH(2)CH(3) (8); R(1) = R(2) = CH(2)CH(3) (9)). The molecular structures of 1-5 and 7 and 8 have been determined by X-ray crystallography.     

Osmium phosphiniminato complexes: synthesis,protonation, structure,and redox-coupled hydrolytic scission of N-p bonds

The osmium(VI) nitrido complex TpOs(N)Cl(2) [1, Tp = hydrotris(1-pyrazolyl)borate] reacts with triarylphosphines to afford the Os(IV) phosphiniminato complexes TpOs(NPAr(3))Cl(2) [Ar = p-tolyl (tol) (2a), phenyl (2b), p-CF(3)C(6)H(4) (2c)] in nearly quantitative yield. Protonation of 2a-c with 1 equiv of HOTf in MeCN occurs at the phosphiniminato nitrogen to give [TpOs(IV)(NHPAr(3))Cl(2)]OTf (3a-c) in 68-80% yield. Solutions of 2a-c in CH(2)Cl(2) react with excess H(2)O over 1 week to form the disproportionation products 1 (28%), TpOs(III)(NHPAr(3))Cl(2) (4a-c) (60%), and OPAr(3) (35%). Treatment of solutions of 3a-c with H(2)O also affords 1, 4a-c, and OPAr(3). X-ray structures of 2b, 3b, and 4b are presented. Cyclic voltammograms of compounds 2a-c exhibit Os(V)/Os(IV) and Os(IV)/Os(III) couples at approximately 0.3 and -1 V versus Cp(2)Fe(+/0). Protonation to give 3 makes reduction easier by approximately 1.2 V, so that these compounds show Os(IV)/Os(III) and Os(III)/Os(II) couples. In the hydrolytic disproportionation of 2a-c, labeling studies using (18)O-enriched O(2) and H(2)O establish water as the source of the oxygen atom in the OPAr(3) product. The conversions are accelerated by HOTf and inhibited by NaOD. The relative rates of hydrolytic disproportionation of 2a-c vary in the order tol > Ph > p-CF(3)C(6)H(4). The data indicate that protonation of the phosphiniminato nitrogen is required for hydrolysis. The mechanism of the hydrolytic disproportionation is compared to that of the related reaction of the osmium(IV) acetonitrile complex [TpOs(NCMe)Cl(2)](+).     

Mechanism and molecular-electronic structure correlations in a novel series of osmium(V) hydrazido complexes

Reaction between the Os(VI) nitrido (OsVI identical to N+) complexes [OsVI(L3)(Cl)2(N)]+ (L3 is 2,2':6',2"-terpyridine (tpy) or tris(1-pyrazolyl)methane (tpm)) and secondary amines (HN(CH2)4O = morpholine, HN(CH2)4CH2 = piperidine, and HN(C2H5)2 = diethylamine) gives Os(V)-hydrazido complexes, [OsV(L3)(Cl)2(NNR2)]+ (NR2 = morpholide, piperidide, or diethylamide). They can be chemically or electrochemically oxidized to Os(VI) or reduced to Os(IV) and Os(III). The Os-N bond lengths and Os-N-N angles in the structures of these complexes are used to rationalize the bonding between the dianionic hydrazido ligand and Os. The rate law for formation of the Os(V) hydrazido complexes with morpholine as the base is first order in [OsVI(L3)(Cl)2(N)]+ and second order in HN(CH2)4O with ktpy(25 degrees C, CH3CN) = (581 +/- 12) M-2 s-1 and ktpm(25 degrees C, CH3CN) = 2683 +/- 40 M-2 s-1. The proposed mechanism involves initial nucleophilic attack of the secondary amine on the Os(VI) nitrido group to give a protonated Os(IV)-hydrazido intermediate. It is subsequently deprotonated and then oxidized by OsVI identical to N+ to Os(V). The extensive redox chemistry for these complexes can be explained by invoking a generalized bonding model. It can also be used to assign absorption bands that appear in the electronic from the visible-near-infrared spectra including a series of d pi-->d pi interconfigurational bands at low energy.     

The remarkable reactivity of high oxidation state ruthenium and osmium polypyridyl complexes

There is a remarkable redox chemistry of higher oxidation state M(IV)-M(VI) polypyridyl complexes of Ru and Os. They are accessible by proton loss and formation of oxo or nitrido ligands, examples being cis-[RuIV(bpy)2(py)(O)]2+ (RuIV=O2+, bpy=2,2'-bipyridine, and py=pyridine) and trans-[OsVI(tpy)(Cl)2(N)]+ (tpy=2,2':6',2' '-terpyridine). Metal-oxo or metal-nitrido multiple bonding stabilizes the higher oxidation states and greatly influences reactivity. O-atom transfer, hydride transfer, epoxidation, C-H insertion, and proton-coupled electron-transfer mechanisms have been identified in the oxidation of organics by RuIV=O2+. The Ru-O multiple bond inhibits electron transfer and promotes complex mechanisms. Both O atoms can be used for O-atom transfer by trans-[RuVI(tpy)(O)2(S)]2+ (S=CH3CN or H2O). Four-electron, four-proton oxidation of cis,cis-[(bpy)2(H2O)RuIII-O-RuIII(H2O)(bpy)2]4+ occurs to give cis,cis-[(bpy)2(O)RuV-O-RuV(O)(bpy)2]4+ which rapidly evolves O2. Oxidation of NH3 in trans-[OsII(tpy)(Cl)2(NH3)] gives trans-[OsVI(tpy)(Cl)2(N)]+ through a series of one-electron intermediates. It and related nitrido complexes undergo formal N- transfer analogous to O-atom transfer by RuIV=O2+. With secondary amines, the products are the hydrazido complexes, cis- and trans-[OsV(L3)(Cl)2(NNR2)]+ (L3=tpy or tpm and NR2-=morpholide, piperidide, or diethylamide). Reactions with aryl thiols and secondary phosphines give the analogous adducts cis- and trans-[OsIV(tpy)(Cl)2(NS(H)(C6H4Me))]+ and fac-[OsIV(Tp)(Cl)2(NP(H)(Et2))]. In dry CH3CN, all have an extensive multiple oxidation state chemistry based on couples from Os(VI/V) to Os(III/II). In acidic solution, the OsIV adducts are protonated, e.g., trans-[OsIV(tpy)(Cl)2(N(H)N(CH2)4O)]+, and undergo proton-coupled electron transfer to quinone to give OsV, e.g., trans-[OsV(tpy)(Cl)2(NN(CH2)4O)]+ and hydroquinone. These reactions occur with giant H/D kinetic isotope effects of up to 421 based on O-H, N-H, S-H, or P-H bonds. Reaction with azide ion has provided the first example of the terminal N4(2-) ligand in mer-[OsIV(bpy)(Cl)3(NalphaNbetaNgammaNdelta)]-. With CN-, the adduct mer-[OsIV(bpy)(Cl)3(NCN)]- has an extensive, reversible redox chemistry and undergoes NCN(2-) transfer to PPh3 and olefins. Coordination to Os also promotes ligand-based reactivity. The sulfoximido complex trans-[OsIV(tpy)(Cl)2(NS(O)-p-C6H4Me)] undergoes loss of O2 with added acid and O-atom transfer to trans-stilbene and PPh3. There is a reversible two-electron/two-proton, ligand-based acetonitrilo/imino couple in cis-[OsIV(tpy)(NCCH3)(Cl)(p-NSC6H4Me)]+. It undergoes reversible reactions with aldehydes and ketones to give the corresponding alcohols.     

Chiral osmium complexes with sterically bulky Schiff-base ligands. Crystal structures of Os(IV) derivatives and the reactivity and catalytic cyclopropanation of alkenes with EDA

The syntheses and reactivities of sterically encumbered trans-dioxoosmium(VI) complexes containing Schiff-base ligands bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-diamine (H2tBu-salch) and bis(3,5-dibromosalicylidene)-1,2-cyclohexane-diamine (H2Br-salch) are described. Reactions of [Os(VI)tBu-salch)O2] (1a) and [Os(VI)(Br-salch)O2] (1b) with PPh(3), p-X-arylamines (X = NO2, CN), N2H4 x H2O, Ph2NNH2, SOCl2, CF3CO2H, Br2, and I2 under reducing conditions gave [Os(II)(Br-salch)(OPPh3)2] (2), [Os(IV)(Br-salch)(p-X-C6H4NH)2] (3), [mu-O-{Os(IV)(tBu-salch)(p-NO2C6H4NH)}2] (4), [Os(II)(Br-salch)(N2)(H2O)] (5), [Os(IV)(tBu-salch)(OH)(Cl)] (6), [Os(IV)(tBu-salch)(OH)2] (7), [Os(IV)(tBu-salch)Cl2] (8), [Os(IV)(tBu-salch)(CF3CO2)2] (9), [Os(IV)(tBu-salch)Br2] (10), and [Os(IV)(tBu-salch)I2] (11), respectively. X-ray crystal structure determinations of [Os(IV)(Br-salch)(p-NO2C6H4NH)2] (3a), [Os(IV)(Br-salch)(p-CNC6H4NH)2] (3b), 6, 8, 9, and 11 reveal the Os-N(amido) distances to be 1.965(4)-1.995(1) A for the bis(amido) complexes, Os-Cl distances of 2.333(8)-2.3495(1) A for 6 and 8, Os-O(CF3CO2) distances of 2.025(6)-2.041(6) A for 9, and Os-I distances of 2.6884(6)-2.6970(6) A for 11. Upon UV irradiation, (1S,2S)-(1a) reacted with aryl-substituted alkenes to give the corresponding epoxides in moderate yields, albeit with no enantioselectivity. The (1R,2R)-6 catalyzed cyclopropanation of a series of substituted styrenes exhibited moderate to good enantioselectivity (up to 79% ee) and moderate trans selectivity.