Sandwich complexes nickel

Sandwich complexes nickel. 5, 35 Sapphyrins, 2, 888 demetallation, 2, 891 metallation, 2, 891 reactions, 2, 891 synthesis, 2, 889 Sarcoplasmic reticulum calcium/magnesium ATPase, 6, 566 skeletal muscle... 

Salicylic acid inhibitor binding dehydrogenases, 1016 Sandwich complexes nickel, 35 Schiff bases... 

TC-Cyclopentadienyl Nickel Complexes. Nickel bromide dimethoxyethane [29823-39-9] forms bis(cydopentadienyl)nickel [1271 -28-9] upon reaction with sodium cyclopentadienide (63). This complex, known as nickelocene, 7T-(C3H3)2Ni, is an emerald-green crystalline sandwich compound, mp 173°C, density 1.47 g/cm. It is paramagnetic and slowly oxidi2es in air. A number of derivatives of nickelocene are known, eg, methylnickelocene [1292-95-4], which is green and has mp 37°C, and bis( 7t-indenyl)nickel [52409-46-8], which is red, mp 150°C (87,88). 

Hydrated nickel(II) salts in the presence of the ligand p3 react with both white phosphorus and yellow arsenic, breaking up the structure of the tetraatomic P4 and As4 molecules to form triatomic cyclo-triphosphorus and cyc/o-triarsenic species. These fragments act as trihapto ligands yielding double sandwich complexes (equation 99).292 The compounds are air-stable both in the solid state and in solution. Upon reduction with NaBH the complexes of equation... 

A typical structure of these so called triple-decker sandwich complexes is that of the complex [(p3)Ni -(j)3-P3) Ni(p3)](BPh4)2-2.5Me2CO (73). In each complex the trihapto P3 (or trihapto As3) groups form a bridge between the two Ni(p3) residues.292 Each nickel atom is thus six-coordinated by three phosphorus atoms from the ligand p3 and by three phosphorus atoms from the cyclo-P3 (or arsenic atoms from the cyclo-As ), which acts as a three-electron-donor ligand. 

Mixed-sandwich complexes with cyclodextrins, 12, 787 iridium cyclopentadienyl complexes, 7, 368 with nickel, synthesis and reactivity, 8, 160 with vanadium, 5, 47... 

The above study has been extended to the synthesis of 4 which was prepared in a similar fashion to 1 and 3 starting from tris(l,4,7-triazacyclonon-l-ylmethyl)benzene [12], The X-ray structure of the [Ni2(4)(H20)3]4+ cation shows that both nickel ions adopt distorted octahedral coordination geometries, with one nickel being sandwiched between two tacn residues while the other is coordinated to the third tacn residue with the coordination sphere being completed by three water ligands. Electrochemical studies indicate that the sandwiched Ni(II) centres in this and the related nickel complexes mentioned above may the be reversibly oxidised to the Ni(III) state. In the case of the dinuclear bis-sandwich complex, [Ni2(4)](C104)4, the electrochemical results indicate that the two nickel centres behave in an essentially independent manner. 

Graham, B., Spiccia, L., Bond, A.M., Hearn, M.T.W., and Kepert, C.M. Structural, sepctroscopic and electrochemical studies of nickel(II) sandwich complexes with ligands featuring tethered 1,4,7-triazacyclononane, Dalton Trans. (2001), 2232-2238. 

The ligands triphos or/ and np in presence of compounds of iron, cobalt, nickel, rhodium, iridium and palladium, by reaction with THF solutions of white phosphorus, P, or yellow arsenic, As, form mononuclear or dinuclear sandwich complexes containing the cyclo-triphosphorus or cyclo-triarsenic units which behave as 3n-electrons rings. 

On the occasion of a visit to England to participate in the first post-war conference on nuclear and radiation chemistry, he was offered a research fellowship by Paneth which he eventually declined. Briscoe advised him that there might not be much future in this kind of nuclear chemistry since he would always be dependent on the physicists running the cyclotron. Wilkinson therefore accepted an offer from MIT to work as a research associate in 1950-1951 thereby returning to coordination chemistry. He prepared some unusual zer-ovalent nickel complexes, such as Ni(PCl3)4 and Ni(PF3)4, and also published a note on an intriguing haemoglobin-PF3 adduct. In September 1951, he was appointed Assistant Professor of Chemistry at Harvard, where he started his seminal work on sandwich complexes that laid the cornerstone of the Nobel Prize. 

Cocondensation of nickel atoms, generated by metal vapor synthesis techniques with t-BuC=P, affords equal amounts of the isomeric sandwich complexes 94 and 95. The former compound features an T -phosphirenyl ligand in addition to an T -l -triphospholyl ring, whereas in 95 the metal is sandwiched between two i74-l,3-diphosphete units see Eq. (19).5,c... 

A bis(2,3-dihydro-l,3-diborole)nickel sandwich complex (27) is formed when Ni(C3H5)2 or Ni(C2H4)3 react with the corresponding 1,3-diborole <85AG(E)943>. 

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