Dinuclear structures

Figure 28.7 (a) Dinuclear structure of copper(II) acetate, and (b) spin singlet (25 +1 = 1) and spin triplet (25 +1=3) energy levels in dinuclear Cu carboxylates. 

The dinuclear rhodium(II) acetate is described in section 2.8.2 the dinuclear structure is retained on one-electron oxidation, but when ozone is used as the oxidant, a compound with a trinuclear Rh30 core is formed, analogous to those formed by Fe, Cr, Mn and Ru. (It can also be made directly from RhCl3.)... 

The role of steric influences on the formation of various vanadium amidinate complexes in the oxidation states +2 and +3 has been studied in detail. The reaction of VCl2(TMEDA)2 and of VCl3(THF)3 with 2 equivalents of formamidinate salts afforded dimeric V2[HC(NCy)2l4 (cf. Section IV.E) with a very short V-V multiple bond and [ [HC(NCy)2 V(/i-Cl)l2 which is also dimeric (Scheme 107). The formation of V2[HC(NCy)2l4 was shown to proceed through the intermediate monomeric [HC(NCy)2l2V(TMEDA), which was isolated and fully characterized. The dinuclear structure was reversibly cleaved by treatment with pyridine forming the monomeric [HC(NCy)2l2V(py)2. ... 

Dioxygen and its ions can bind in mononuclear and dinuclear structures in a number of ways,962 as illustrated in Scheme 1. The typical reaction of dioxygen with Co compounds involves a number of these binding forms, outlined in Scheme 2. Mononuclear Co111—peroxo complexes are relatively rare, but yellow trigonal bipyramidal complexes [Co(02)L2]+ (L = chelating phosphines dppe or dppp) have been characterized structurally where the 022 is bonded to the Co in the side-on r]2 form (Co—O 1.858(7) 1.881(4) A), with O—O stretching frequencies ( 870 cm-1) consistent with Coin-peroxo speciation.963... 

The general dinuclear structural motifs are of the weakly linked, 1, or covalently-bridged, 2, types shown in which... 

Sharpless suggested that epoxidation was catalyzed by a single Ti center in a dimeric complex with a C2 symmetric axis. Molecular weight measurement, infrared spectroscopy, and H, 13C, and 170 NMR spectrometry all suggest that such a dinuclear structure is dominant in the solution phase (Fig. 4-2).10... 

Formula TaCls MW 358.21 shows a dinuclear structure, Ta2Clio, but in vapor phase it exists as a mononuclear, TaCls, having a trigonal bipyramidal shape. 

Treatment of TiBr4 with B2[NMe2]4 produces B2Br2[NMe2]2-TiBr3, for which the dinuclear structure (50) is proposed.174 Complexes M2[TiBr5(H20)] (M = Cs, Rb, pyH) are known.175... 

When ammonia gas is bubbled through a suspension of the acetate in ethanol, ammonia molecules replace the water, but in liquid ammonia the dinuclear structure is destroyed to give the tetraammine (Scheme 17). Unless kept in an atmosphere of ammonia the tetraammine reverts to the dinuclear ammine adduct.161... 

The kinetics of the oxidative addition of nitriles to Ni(P—P)2 have been studied. The organocyano nickel(II) complexes presumably have a dinuclear structure with trans planar coordination for the nickel atom.270 Some of the [Ni(CN)(R)(PR3)2] compounds (R = alkyl, aryl) are unstable and therefore cannot be isolated in the solid state. Their decomposition in solution promotes the formation of alkanes, alkenes, diphenyl, etc.217... 

Deprotonated 1,3-diphenyltriazene, PhNNNPh-, gives a dinuclear complex [Ni2L4] which has been found to possess a dinuclear structure with bridging triazenato ligands reminiscent of (100).834 835... 

Ni(acac)2 reacts with a variety of monodentate donors giving mono and bis adducts Ni(acac)2B (n = 1,2 B = H20, primary and secondary amines, pyridine and substituted pyridines, pyridine iV-oxide, alcohols, dioxane, substituted benzaldehydes).1558,1563-1570 Details of the structures of some complexes are reported in Table 78. The chelate ring of the coordinated /3-diketones is nearly planar, and, in thl mononuclear complexes, the Ni—O bond distances (as well as the C—O and C—C bond distances within the chelate ring) are substantially similar. Two different dinuclear structures have been found in the two complexes Ni2(acac)4B [B = py (197),1540,1571,1530 Ph3AsO (198)1542,1572]. 

A homologous series of nickel(II) complexes with the general formula Ni2L(tren)2(BPh4)2 has been prepared with the dianionic ligands L which arise from the deprotonation of the neutral molecules (202)-(207).1604-1606 All of these complexes are assumed to exhibit the same dinuclear structure (208) as found in the complex with L = chloroanilate (202).1604... 

Dinuclear structure the molecule 1956 is folded about the bridging thiols Ni—S, 214-222 pm... 

The reaction of various monothiocarboxylic acids RC(S)OH (R = Ph, Et, Me) in alkaline solution with nickel(II) results in the isolation of complexes of general formula [ Ni(RCOS)2 2-EtOH] (,ueff = 2.3-2.4 BM).2476 These complexes have a dinuclear structure exemplified by that of [ Ni(PhC(S)0)2 2-Et0H] (340).2477 In this complex both nickel atoms have five neighbours one nickel is bound to four oxygen atoms of four different thiobenzoate anions, and to the oxygen atom of EtOH the other nickel is bound to four sulfur atoms of thiobenzoates and to an additional sulfur atom belonging to the centrosymmetrically related molecule. 

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