Related Complexes

The cationic allene complexes (32) (R, R , R , R = H or Me) undergo rotation about the n -bond with barriers that increase with increasing alkyl substitution of the allene - particularly at the syn-C-3 position. Intramolecular syn-anti isomerization of (32) is a higher-energy process but becomes easier with increasing substitution e.g. AC = 23.1 kcalmol-i (R = R = R = H, R =Me) and AG = 16.3 kcal mol (R = R = R = R = Me). The mechanism for this isomerization involves a series of 1,2-shifts and a planar intermediate cannot be formed since chirality is retained in optically active j -cyclopentadienyl-( -cyclonona-l,2-diene)dicarbonyliron cation. 

An increasing volume in the literature is devoted to pseudo-cyclopentadienes and pseudo--arenes. A general paper describes complexation of the cyclo-Ps anion. The synthesis of the first diazacobaltocene has been described. Tert-butyl-substituted diazaferrocenes have been prepared from substituted pyrroles. Bis-(borole)nickel complexes have been prepared from dilithium txnelediides. Carborane stabilised iron indole and iron thiophene complexes have been made. The electrophilic stacking of borataferrocene and bis(borole)cobaltate ions with -Cr(CO)3 and Mn(00)3 has been described. The synthesis and crystal structure of 

Wright, Chapter 14, in Organonetallic Chealstry , Eds. E.U. Abel and F.G.A. Stone, SPR. The Royal Society of Chemistry, Cambridge, 1991, 

G6mez-Sal, B. Royo, P. Royo, R. Serrano, I. Sdez and S. Hartinez- 

Organomet. Chem., Winter and S. Woodward, J. Organomet. Chem. 

Haclejewskl Farmer, R.C. Haltlwanger, F. Kvietok and M. Rakowski Du Bols, Organometallics, 1991, 10, 4066. 

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The structure of the metallocene cation energy minimised with the Car-Parrinello method agrees well with the experimentally obtained crystal structures of related complexes. Typical features of the structure as obtained from X-ray diffraction on crystals of very similar neutral complexes (e.g., the dichlorides), such as small differences in distances between C atoms within a cyclopentadienyl (Cp) ring, as well as differences in distances between the C atoms of the Cp ring and the Zr atom, were revealed from the simulations. 

Tris(2,4-pentanedionato)iron(III) [14024-18-1], Fe(C H202)3 or Fe(acac)3, forms mby red rhombic crystals that melt at 184°C. This high spin complex is obtained by reaction of iron(III) hydroxide and excess ligand. It is only slightly soluble in water, but is soluble in alcohol, acetone, chloroform, or benzene. The stmcture has a near-octahedral arrangement of the six oxygen atoms. Related complexes can be formed with other P-diketones by either direct synthesis or exchange of the diketone into Fe(acac)3. The complex is used as a catalyst in oxidation and polymerization reactions. 

Many related complexes, such as the platenomycin complex (initially YL-704) from S. platensis suhsp. malvinus have been obtained (201—206). A series designated by abbreviations (DHP, DOA) was obtained from another strain of S. platensis (207) the midecamycin complex (initially SF-837) was produced by S. mjcarojaciens (208—212) the espinomycin factors were produced by S. Jungicidicus var. espinomjceticus (213,214) the turimycin series of fifteen components, isolated from culture broths of S. hjgroscopicus are identical to other members of the leucomycin group (215). Niddamycin (42, R = H, R = butyryl) was isolated from cultures of S. djakartensis (216). 

Another dideoxypyrimidine nucleoside active against human immunodeficiency vims is 3 -azido-2/3 -dideoxyuridine [84472-85-5] (AZDU or CS-87, 64) C H N O. Since its synthesis, (167) CS-87 has been identified as a promising antiHIV agent (168) and is currentiy undergoing phase I clinical trials in patients with AIDS and AIDS-related complex. It appears to be less potent than AZT against HIV in a peripheral blood mononuclear (PBM) cell screening system and in MT-4 cell lines. This lower activity in PBM cells appears to be related to a lower affinity of CS-87 for the enzyme responsible for its initial phosphorylation (169). However, CS-87 has significantly lower toxicity on bone marrow cells than AZT (170) and penetration of the CNS as a 5 -dihydropyridine derivative. 

Piezochromic effects have been observed in a variety of other Cu(II) complexes. In some cases it can be shown that the stmctures of a series of related complexes foUow a reaction pathway with the stmcture of one complex at, for example, 8 GPa (80 kbar) corresponding to that of a related complex at, for example, 2 GPa (20 kbar). The changes in color of the complex, of course, foUow the same sequence. 

H. W. Roesky and K. K. Pandey, Transition-Metal Thionitrosyl and Related Complexes, Adv. Inorg. Chem. Radiochem., 26, 337 (1983). 

Similar structural diversity has been established for the heavier alkali metals also but it is unnecessary to deal with this in detail. The sUTictural chemistry of the organometallic compounds in particular, and of related complexes, has been well reviewed. 

Mechanism of the Catalysis of the Bis(N-octyl-2-imidazolyl)-carbinol(38c)-Zn2 + ion and of Related Complexes... 

Using the chelating phosphine bis(diphenylphosphino)ethane (dppe) a related complex Ir(dppe)Jcan be made [123]... 

Metal 1,2-dithiolene and related complexes. J. A. McCleverty, Prog. Inorg. Chem., 1968, 10, 49-221 (188). 

Iron(II) diimine and related complexes. P. Krumholz, Struct. Bonding (Berlin), 1971, 9, 139-174 (233). 

Thiocarbonyl and related complexes of the transition metals. P. V. Yaneff, Coord. Chem. Rev.,... 

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