Dinuclear compounds

The dinuclear compounds of molybdenum(II) have strong, quadmple, molybdenum—molybdenum bonds and ecHpsed stmctures, such as those of Mo2CF g (Fig- 6 ) Mo2(02CCH3)4 (Fig. 6b). These quadmply bonded complexes have been intensely studied from the point of view of their... 

Ruthenium provides more examples of dinuclear compounds in which the metal is present in a mixture of oxidation states (or in a non-integral oxidation state) than any other element. 

Dinitrogen monoxide reductase, 6, 727 Dinuclear compounds symmetrical nomenclature, 1,122 unsymmetrical nomenclature, 1,123 Dioctylamine... 

The interplay between magnetic coupling and ST in 2,2 -bipyrimidine (bpym)-bridged iron(ll) dinuclear compounds has been studied by magnetic susceptibility and Fe Mossbauer spectroscopy [24]. The molecular stmctures of [Fe(bpym) (NCS)2]2(bpym) and [[Fe(bt)(NCS)2]2(bpym) (bt = 2,2 -bithiazoline) are shown in Fig. 8.12. The magnetic behavior in the form of XmT versus Tplots, being the... 

These results obtained in applied field clearly prove that the ST in the dinuclear compounds under study proceeds via [HS-HS] O [HS-LS] O [LS-LS]. Simultaneous ST in both iron centers of the [HS-HS] pairs, leading directly to [LS-LS] pairs, apparently can be excluded, at least in the systems discussed above. This is surprising in view of the fact that these dinuclear complexes are centrosymmetric, that is, the two metal centers have identical surroundings and therefore, experience the same ligand field strength and consequently, thermal ST is expected to set in simultaneously in both centers. In other dinuclear iron(II) complexes, however, thermally induced direct ST from [HS-HS] to [LS-LS] pairs does occur and, indeed, has been observed by Mossbauer measurements [30, 31]. 

Triphos-derived tridentate ligands with mixed donor sets have been developed and subsequently used in Ni coordination chemistry. Nickel(II) complexes include dinuclear compounds (254) and (255) with P2S and P2O ligands, respectively.6... 

Compartmental pyrazole ligands (14) can be used to form bimetallic complexes (15).157 This ligand enforces a separation distance between the metal ions. Stability constants were calculated showing a stability for both mononuclear and dinuclear compounds that was less than Cu11 but greater than Nin. 

A particularly interesting question which remains unanswered is whether dinuclear photoproducts are produced directly from the photoexcited parent molecule or whether they are formed by reaction of free radicals within the solvent cage. In principle this question can be answered by making time-resolved IR measurements on the molecules in the gas phase, where no solvent cage can interfere. Thus, it may transpire that a full understanding of the photolysis of these dinuclear compounds will require complementary experiments in solution and in the gas phase. 

First examples of complexes of a,cj-digold alkylidenes have been prepared in moderate yields from the corresponding di-Grignard reagents with 2 equiv. of (Ph3P)AuBr as colorless, crystalline products. The structure of the dinuclear compound with the -(CH2)4- spacer has been determined (Equation (3)).19 Preparative efforts oriented at the synthesis of the analogous ethane, propane, and hexane derivatives were unsuccessful. 

Functions [R2Au] are also present in the large family of gold(i) complexes of phosphonium, arsonium, and sulfonium ylides . Section 2.05.6 is dedicated to this class of complexes, where dinuclear compounds with gold in the oxidation state +2 are also common. 

The most straightforward synthesis of compounds (L)AuAr uses the metathesis of (L)AuX precursors with aryllithium reagents, as, for example, executed for the preparation of (Ph3P)AuPh. The crystal structure of this benchmark complex has been determined. The linear coordination geometry is as expected. No aurophilic contacts are discernible in the crystal packing. Short Au- -Au contacts are observed, however, in the dinuclear compound (dppm)(AuPh)2 with an intramolecular intermetallic distance of 3.154(1) A. This complex shows a UV-VIS absorption at 290-300 nm and is luminescent in fluid solution at room temperature.1... 

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