Polynuclear compounds, inert metal

Polynuclear complexes, 32 56 osmium, electrochemistry, 37 321-323 X-ray diffraction, 39 217-225 Polynuclear compounds, inert metal complexes, 34 186... 

The carbonyls are in general volatile compounds with an extensive chemistry which presents many problems as regards valence and stereochemistry. Some are reactive and form a variety of derivatives, as shown in Chart 22.1 for the iron compounds, while others are relatively inert, as for example, Cr(CO)6 etc. and Re2(CO)iQ. This rhenium compound, although converted to the carbonyl halides by gaseous halogens, is stable to alkalis and to concentrated mineral acids. A few carbonyls may be prepared by the direct action of CO on the metal, either at atmospheric pressure (Ni(C0)4) or under pressure at elevated temperatures (Fe(CO)s, Co4(CO)i2)- Others are prepared from halides or, in the case of Os and Re, from the highest oxide. The polynuclear carbonyls are prepared photo-synthetically, by heating the simple carbonyls, or by other indirect methods. 

An obvious problem that was of interest to workers in the field of metal carbonyl clusters was the prospect of predicting the structures of the compounds obtained. The principle of the attainment of the inert gas configuration by the metal atoms was one of the guiding rules applied in all the early considerations of the structure of these compounds. A major development occurred when Wade drew an analogy between the structures of the metal carbonyls and boron hydride compounds whose structure were well established. Using this approach Wade was able to predict the correct structure for a number of polynuclear metal carbonyls many of which had been rationalised in terms of the effective atomic number rule. One of the early successes of the Wade approach was the structure of [Os6(CO)ig], Fig. 2, which was... 

In general, the sensitivity towards hydrolysis of metal phosphides depends on the metal content. Metal-rich compounds undergo relatively straightforward hydrolysis while the behavior of those with higher phosphorus content resembles more that of the elementary phosphorus, specially with respect to their inertness toward water. As observed in Table 4.16, many polynuclear metal phosphide undergo hydrolysis giving rise to corresponding phosphor hydrides or phosphanes. 

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