Complexes homoleptic

In 1956 it was found that europium and ytterbium dissolve in liquid ammonia with the characteristic deep blue color known for the alkali and alkaline earth metals [36-40]. This behavior arises from the low density and high volatility of those metals compared to the other lanthanide elements [41]. Samarium, which normally also occurs in the divalent oxidation state, does not dissolve under 

The initially formed ammoniates Ln(NH3)6 (Eq. la) can be isolated by evaporation of NH3 as gold metallic solids and low temperature X-ray studies at 200 K reveal a body-centered cubic array of octahedral molecules [38a]. Eu(NH3)6 can easily be converted to pure Eu(NH2)2 by catalytical (Fe203) [40a] and thermal (50 °C) treatment [40b] (Eq. lb,c). In the case of ytterbium 

Microcrystalline imides, e.g., Lao.eeeNH [44b] and imide-nitrides, e.g., Ce3(NH)3N [49b] were obtained by thermal decomposition of amide precursors. 

What is the message of these inorganic metal amides As hydroxides are never classified to alkoxides, NH2 amides seem to be treated separately from the 

---

Hahde ligands are found in homoleptic complexes as well as in mixed ligands systems. HaUde complexes of Ir(IV) such as [IrCy [16918-91-5] are readily reduced to Ir(III) species, eg [IrCy [14648-50-1], in neutral or basic solution, or in the presence of reducing agents such as KI, oxalate, or photochemical activation (173). 

Hydrocarbyl Complexes. Stable homoleptic and heteroleptic uranium hydrocarbyl complexes have been synthesized. Unlike the thorium analogues, uranium alkyl complexes are generally thermally unstable due to P-hydride elimination or reductive elimination processes. A rare example of a homoleptic uranium complex is U(CH(Si(CH2)3)2)3, the first stable U(I11) homoleptic complex to have been isolated. A stmctural study indicated a triganol... 

Chromium alkyls [(>j -(3-t-Bu-5-Mepz)3B)CrR] (R = Et, CH2SiMc3, Ph) follow from the corresponding homoleptic complexes and alkyllithium compounds (97CEJ1668). 

In a similar fashion, the homoleptic complex [Pd(ITmt) ] lb readily reacts with O2 to form the corresponding peroxo-complex 2b (Scheme 10.1). This complex, npon exposure to CO, leads to the peroxo-carbonate complex 3b [10]. Under the same reaction conditions, the formation of 3a does not occur, presumably due to the larger steric hindrance of the Mes ligand. 

The four-coordinate homoleptic complexes [Ag(EPh3)4]+ (E = P, As, Sb) have been characterized structurally with several anions for PPh3, with N03-,664 rSnPh2(N03)2(Cl,N03)]- (disordered distribution between Cl and NOD,679 C104, 680 PF<, , 682 and BPh4 683 for AsPh3, with... 

Homo- and heteroleptic complexes of Cd alone and of Cd and Hg with the ligand dicyanamide (dca) N(CN)2-, homologous to cyanamide NCN2-, have been studied in various solvents (formation constants of the complexes [M(dca) ](" 2> (M = Cd, Hg l < n < 4)), with the result that the complexes of Hg are more stable than those of Cd. Otherwise, obviously no studies on the isolated compounds M(dca)2 or on homoleptic complexes derived therefrom have been published. 

Homoleptic complexes have been obtained also with tetrakis(l-pyrazolyl)borates, e.g., [ B(pz)4 2Cd] and [ B(3-Mepz)4 2Cd] (both P2 jc, Z = 2) in both compounds structure analyses the ligands have been shown to coordinate trihapto, i.e., with one pz ring free. In both cases Cd has a distorted octahedral environment, with averaged structural data very similar to those for the tris(l-pyrazolylhydridoborate complexes.201 Variable-temperature 3H NMR studies of these and of mixed complexes with tris- and bis(l-pyrazolylhydridoborates indicate fluxional behavior (coalescence temperatures and barriers for the dynamic processes are given). 

Figure 2.8 is a partial snapshot of the recent progress in the construction of this general library, taken from Ref. [23]. Only the homoleptic complexes which can be fitted by the REC model are included. In the case of the halides F-, Cl-, Br-, energy levels were used [21]. For oxygen, two series of a total of 10 POM complexes were used, but in this case only xT data were available. For nitrogen, a combination of simultaneous fits, xT data and spectroscopic data, was used [22, 24]. In this comparison we chose to depict the position... 

Scheme 8.1 Three key methods of the synthesis of lanthanide(lll) bis(phthalocyanine) complexes. Homoleptic complexes symmetrical (A, B) and unsymmetrical (C1 and C2, D1). Thereby, the thermal fusion group A can be subdivided into (A1) solvent free fusion (A2) refluxing in the mixture of protic solvents in the presence of organic base - DBU and (A3) MW assisted fusion.

Like I+ (vide infra), H+ can form bis(carbene) complexes, 9 (13). These homoleptic complexes, which feature C-H-C interactions, were formed by treatment of 4 (R = Mes R = H) with the corresponding... 

Particularly interesting are the homoleptic complexes 46 to 49 (Figure 2.3-7) in which Ni or Pt atoms are tetrahedrally coordinated by four Ga-R or In-R ligands [71, 72]. These compounds are analogues of Ni(CO)4. They have relatively short M-Ga or M-In bond lengths, and quantum-chemical calculations verify an effective 71-back bonding of electron density from the transition metal atom into the empty p-orbitals of the E-R groups. 

Inspection of Table 7.13 leads to the conclusion that the Fe-EMe BDEs of the homoleptic complexes Fe(EMe)5 are higher than their counterparts predicted for the (CO)4Fe-EMe bonds. The homoleptic group-13 complexes M(EMe)4 are also predicted to have high bond energies, except for the Pt-AlCp and Pt-GaCp BDEs in Pt(dhpe) (ECp)2 that are rather low. 

Scheme 12.13 (a) Proposed surface species 48 via route 6, R = Me or (AlMe ) (b) of hybrid materials resulting from different proposed surface species of hybrid materials consecutive graftings of homoleptic complex 51a and 51b after immobilization of the Nd(AlMei)3 and EtjAICl onto MCM-48280 heteroleptic complex Cp Nd(AlMe4)2 on... 

Plummer, D.T. and Angelici, R.J. (1983) Synthesis and characterization of homoleptic complexes of the chelating bidentate isocyano ligand tert-BuDiNC. Inorg. Chem., 22, 4063. 

As discussed above, lanthanides and group 3 homoleptic complexes are attractive initiators because of their moderate Lewis acidities, good activities of polymerization, and low toxicity [94, 111, 112, 115-118]. A list of lanthanide initiators and their polymerization activity is listed in Table 5. 

---