Homonuclear Bonds between Transition Metals

Homonuclear Bonds between Transition Metals.—Titanium. 

Homonuclear Bonds between Transition Metals.—Tables 1 and 2 list structural determinations carried out since the end of the last report on dinuclear and polynuclear compounds containing metal-metal bonds. 

The term Zintl phase is applied to solids formed between either an alkali- or alkaline-earth metal and a main group p-block element from group 14, 15, or 16 in the periodic table. These phases are characterized by a network of homonuclear or heteronuclear polyatomic clusters (the Zintl ions), which carry a net negative charge, and that are neutralized by cations. Broader definitions of the Zintl phase are sometimes used. Group 13 elements have been included with the Zintl anions and an electropositive rare-earth element or transition element with a filled d shell (e.g. Cu) or empty d shell (e.g. Ti) has replaced the alkali- or alkaline-earth element in some reports. Although the bonding between the Zintl ions and the cations in the Zintl phases is markedly polar, by our earlier definition those compounds formed between the alkali- or alkaline-earth metals with the heavier anions (i.e. Sn, Pb, Bi) can be considered intermetallic phases. 

Mixed transition metal-main group element clusters are ultimately related to either homonuclear metal or main group element clusters. Although there are similarities between the bonding within these two limiting types of clusters, there are also significant differences, ft is these differences in the mixed... 

Parallel to the development of the chemistry of dinuclear transition metal complexes with metal-metal bonds, studies related to bimetallic complexes, hetero- and homonuclear, without metal-metal bonds are appearing in the literature at ever increasing frequency (10-13). In these complexes, two or more metals are separated by a common ligand which acts as a bridge between them. Two metal centers acting in a joint fashion could enhance the activation of an organic substrate considerably and in... 

Rogl and Nowotny (1978) have observed that the type of homonuclear linkage in borides can be correlated in simple form with the metal boron ratio of the compound. All ternary rare earth-transition metal borides are listed in table 20, arranged according to decreasing metal boron ratio, and the observed homonuclear linkage of the B atoms. One notes that if the ratio is larger than 1.75 only isolated B atoms occur. Boron dumbbells are found with values between 1,3 and 1.0. Two homonuclear bonds occur first with a metal to boron ratio of 1 and three... 

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