Homoleptic complexes structure

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... 

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). 

The homoleptic complex exists in the solid state as a dimer (CN of Th is 5), whose structure can be considered as two ThOs units (in a trigonal bipyramidal geometry) joined along a common axial-equatorial edge [281], At room temperature, in noncoordinating solvents, there is a monomer-dimer equilibrium (5.51) [308,311] ... 

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(CH3)3)2)3, the first stable U(III) homoleptic complex to have been isolated. A structural study indicated a triganol... 

There are roughly 50 homoleptic tris (dithiolene) complexes reported in the CSDC (5). The elemental distribution of these structures is outlined in Fig. 15. As opposed to bis(dithiolene) complexes, tris(dithiolene) complexes are based predominantly on early transition metal elements. Many of the tris(dithiolene) complexes are centered on V, Mo, and W. There are also complexes of Ti, Zr, Nb, Ta, Cr, Tc, Re, Ru, and Os. In addition, there are tris(dithiolene) complexes of Fe and Co, elements that also form homoleptic complexes with two dithiolene ligands. A detailed listing of the structural units along with references and geometrical parameters (to be discussed) is given in Table IV. 

The Cu ion is classified as a soft acid (see Hard Soft Acids and Bases), which predicts reasonably well the types of ligands that will be most stabilizing and are, thus, commonly observed in Cu complexes. The preference of Cu for softer ligands is quite apparent in the homoleptic complexes, for instance the halides discussed above. Polynuclear compounds are quite commonly seen in the chemistry of Cn. Thus, the solid-state structure cannot be reliably predicted from the reaction stoichiometry or from the empirical formula of the resulting compound. The careful selection of ligands, for instance, an appropriate macrocyclic ligand can ensnre the formation of a mononuclear complex if one is desired. 

The synthesis, structure, and physical and chemical properties of organo-lanthanide complexes containing only polyhaptocyclopentadienyl and cyclooctatetraenyl metal-carbon bonds are fully covered in other reviews (5-7). This section will focus on lanthanide-carbon single bonded species only. Ln—C single bonds are found almost exclusively in only two types of complexes homoleptic complexes, and heteroleptic... 

The reaction between Pd(acac)2 and lithium / -diketiminate, a nitrogen derivative of acac, gives a mixed-ligand and homoleptic complex. Interestingly, these complexes are stable at ambient temperature, but in acetonitrile solution they decompose to elemental Pd presumably due to reaction of Pd(II) and the acac ligand. Fmthermore, in pentane or ether solution the complex can isomerize into the thermodynamically stable form. Both isomers are similar, but their NMR spectra are inequivalent due to an asymmetric structure with nonrotating substituents. Since one of the imine groups is coordinated to the Pd ion, this isomerization results in the formation of a chiral center at the coordinated C atom. 

Trivalent homoleptic complexes An[N(SiMe3)2]3 have been generated for uranium, neptunium, and plutonium " by metathesis reactions (see Equations (1) and (2)). The molecular structure of U[N(SiMe3)2]3 has been determined ... 

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