Coordination organization

As an illustration of the phosphorus-carbon analogy, consider the result of replacing a carbon fragment (CR2) by a phosphorus moiety (PR) in each of the common low-coordinate organic compounds (1C-4C) shown in Fig. 1. For example, the replacement of a single carbon in an alkene (1C) results in a phos-phaalkene (IP). Similarly, the phosphaalkynes (2P) are isolobal relatives of the alkynes (2C), and terminal phosphinidene complexes (3P) can be related to the... 

Silicon-containing Bimetallics Fe-M (M = Ni, Pd, Pt) with M-Coordinated Organic Ligands... 

John, G.R. and Mane-Maguire, A.P, Kinetics of nucleophilic attack on coordinated organic moieties. Part 7. Mechanism of addition of tertiary phosphines to tricarbonyl(dienyl)iron cations, /. Chem. Soc., Dalton, 873, 1979. 

It will be seen from Table 5 that the variation of parameters with atomic number is by no means always monotonic. The explanation of this must again be connected with variation of coordination number along the series of lanthanides. If the strongly coordinating organic ligands are reasonably assumed to exert their full ligancy, then any variation must be in the extent of inner-sphere hydration of the various species, as it is rather unlikely that there is a... 

Alternatively, the azide anion can be added to coordinated organic isonitrile (211) or nitrile (60) ligands to give the same products. Coordination of RCN ligands greatly increases their susceptibility to attack by azide anions reactions typically go to completion in 15 minutes at 25°C (60). 

Other reports confirm similar reaction of C02 with metal alkoxide compounds. Benzene solutions of the alkoxide compounds Ti(OBu")4, Zr(OBu")4, Zr(OEt)4, Nb(OEt)5, and Fe(OEt)3 were found to absorb carbon dioxide in various amounts (151). Only Zr(OBu")4 reacted with an amount approaching one equivalent per metal complex. The solution ir spectra indicate formation of coordinated organic carbonates. From this evidence, equilibrium formation of the species M(0R) 1(02C0R) under 1 atm of C02 is inferred. 

As early as 1969, Pedersen was intrigued by the intense blue colour observed upon dissolution of small quantities of sodium or potassium metal in coordinating organic solvents in the presence of crown ethers. Indeed, the history of alkali metal (as opposed to metal cation) solution chemistry may be traced back to an 1808 entry in the notebook of Sir Humphry Davy, concerning the blue or bronze colour of potassium-liquid ammonia solutions. This blue colour is attributed to the presence of a solvated form of free electrons. It is also observed upon dissolution of sodium metal in liquid ammonia, and is a useful reagent for dissolving metal reductions , such as the selective reduction of arenes to 1,4-dienes (Birch reduction). Alkali metal solutions in the presence of crown ethers and cryptands in etheric solvents are now used extensively in this context. The full characterisation of these intriguing materials had to wait until 1983, however, when the first X-ray crystal structure of an electride salt (a cation with an electron as the counter anion) was obtained by James L. Dye and... 

Other synthetic routes involving mild conditions and not requiring specialized apparatus involve displacement of carbon monoxide from metal carbonyls (method I) or coordinated organic ligands (arenes,... 

ANSI was founded in 1918 to coordinate standardization activities in the private sector, and today it is the coordinating organization in the U.S. national standards system. In contrast with ASTM it does not develop standards, but it does provide the mechanism for determination of need and arranges for competent organizations to perform the standards development work. The membership of ANSI consists of about 1000 companies and more than 200 trade, technical, professional, labor, and consumer organizations (7). 

The stability of carbocations flanked by n-coordinated organic moieties is dramatically enhanced so that they react easily with nucleophiles [125]. Magnus et al. [126] applied this principle to the synthesis of the core structure (208) of the diynene antibiotics esperamicim and calicheamicins. As shown in Scheme 68, diynene 205 was converted to enol silyl ether which was treated with Co2(CO)g to give dicobalt hexacarbonyl adduct 206. Exposure of 206 to 3 equiv of TiCU and 1 equiv of DABCO at —43 to —35 °C gave macrocycle 207 in 50% yield. 

The cationic dinitrosyl complexes (146) are apparently much more electrophilic than (143). Studies of the reactivity of (146) have been focused on attack of coordinated organic ligands of other transition metal complexes, such as the cyclooctatetraene ligand in L3M(cot) complexes (M = Fe, Ru) and Cp Co(cot) complexes (Cp = Cp, Cp ), the cyclopenta-dienyl ligand of CpRh(cot) complexes, and the cyanide ligand... 

The absorption spectra of rare earth complexes are mainly determined by the coordinated organic ligands. 

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