Homoleptic molecule

E = Sb. In the same paper [23] we reported also about the bonding situation in the mixed Cp/Es complexes FeCpCri -Es). The EDA results showed that there are no major changes in the relative contributions of the energy components in the mixed complexes compared with the homoleptic molecules. Therefore we do not give the data here. The interested reader may read the original publication [23]. 

The metal-methyl mean bond dissociation enthalpies in the main-group homoleptic molecules, MMe , vary from 131 kJmoF in ZnMc2 to 283kJmoF in AlMc3. Thus, the above value for Z) (M-Me) in a transition metal complex is not particularly high, suggesting that many cootdinatively unsaturated transition metal complexes would activate methane. 

A number of general features in Table 1-3 is apparent. Complexes may be cationic, neutral or anionic. Ligands may be simple monatomic ions, or larger molecules or ions. Many ligands are found as related neutral and anionic species (for example, water, hydroxide and oxide). Complexes may contain all of the same type of ligand, in which case they are termed homoleptic, or they may contain a variety of ligand types, whereby they are described as heteroleptic. Some ligands such as nitrite or thiocyanate can coordinate to a metal ion in more than one way. This is described as ambidentate behaviour. In such cases, we commonly indicate... 

Technetium complexes with thioethers in the strict sense, i.e., those without other donor groups in the ligand molecule, comprise homoleptic thioether nitridotechnetium(V) complexes [111], cationic mixed thioether/thiolate complexes of Tc(III) [112], and a cationic Tc(I) complex [113]. However, these latter compounds do not properly fall within the scope of Tc(V) compounds and are excluded from review. 

The Tc complex [TcI(N—Ar)s] (28) (see Section 5.2.2.1.2) can be reduced with Na° in THE to yield the green, nonbridged, dinuclear compound [Tc2(NAr)6] (46), in which three imido-ligands are bound to the Tc center and connected by a single bond to the second technetium. The molecule has a staggered, ethane-like structure and is diamagnetic. Reduction of (28) yields another homoleptic imido-complex of Tc, the imido-bridged, tetrahedral, dinuclear compound [Tc2(/u-NAr )2(NAr )4] (47) (Ar = 2,6-diisopropylphenyl). The conformation could be confirmed by X-ray structure analysis the assumption of a Tc Tc bond is confirmed by the... 

Neutral homoleptic transition amide molecules are for the most part soluble in commonly used aprotic solvents. They are, in effect, hydrocarbon-soluble soiuces of M"ions, and because of the polarity of the M—N bond they can readily be used for the synthesis of a wide variety of reagents. The most common reactions involve the insertion of unsamrated species into the M—N bond or M—N bond cleavage reactions with protic molecules. Their utility can be illustrated by the reactions of some divalent Co) ) amides, shown in Scheme 6.2. 

Typical examples of this reaction involve the heterocumulenes C02, CS2, COS, RNCO, RNCS and other related molecules such as S02, S03, RC=N and RNC, and activated alkynes bearing strongly electron-withdrawing substituents such as C02Me. These reactions find utility in the syntheses of homoleptic carbamates (equation 77),223 monothiocarbamates and dithiocarbamates from homoleptic amides though redox reactions can occur in some instances (equations 78102 and 79224). 

Fig. 5.7 Luminescence of homoleptic and heteroleptic [Ru(bipy)3]2+ complexes as a function of the number of oxygen atoms in the molecule - and hence of the steric shielding of the central ion (according to Balzani, Vogtle et al.)...

Adducts Ln(btsa)s(A). The availability of additional coordination sites was shown in Ln(btsa)3 complexes by isolation of their mono adducts OC(PPh3) [124] and OCPh2 [125], respectively, and their bis adducts of benzonitril [108], The stabilizing Ln - Si contacts in the homoleptic Ln(btsa)3 systems are obviously replaced by a stronger hard Ln <- donor atom coordination. Other adduct complexes include the donating molecules THF [84], NCtBu and CNtBu [109b]. 

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