Phosphides with Complex Anions

In the compound Ba3Sn2P4 continuous covalently linked chains are formed by edge sharing of (Sn2P4) units [34] (8.23a), while in Sr3ln2P4, continuous chains are formed by corner sharing of InP units [35] (8.23b). Similar InP units form infinite chains in the structure of KjNahiPj [36] (8.23c). 

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The different types of crystal structure found amongst the ternary phosphides are far too numerous to be systematically dealt with here [43-45]. When one component is an alkali or alkaline earth metal, complex anions are liable to be formed (Section 8.4). Most of the ternary phosphides already cited involve replacement one metal atom by alternative atoms while retaining the original type of structure (Figures 8.3, 8.4 and 8.11). 

In accordance with the electropositive nature of the bridgehead atoms, all di(pyridyl) substituted anions behave like amides with the electron density accumulated at the ring nitrogen atoms rather than carbanions, phosphides or arsenides. The divalent bridging atoms (N, P, As) in the related complexes should in principle be able to coordinate either one or even two further Lewis acidic metals to form heterobimetallic derivatives. According to the mesomeric structures, (Scheme 7), it can act as a 2e- or even a 4e-donor. However, theoretical calculations, supported by experiments, have shown that while in the amides (E = N) the amido nitrogen does function as... 

Research has shown that when polychlorpinen, ammonium nitrate, and superphosphate are present together in the soil, phosgene, carbon monoxide, nitric oxide, hydrochloric acid, ammonia, hydrocyanic anions, ozone, hydrogen fluoride and phosphide, etc. could appear in the air over the beet fields. Photooxidants could also appear. Airborne toxic compounds over this crop were noted in areas after precipitation with little wind, and with an air temperature of over 2CP . The combined and complex activity of pesticides and other chemical compounds led people who manually sowed beets to develop symptoms of poisoning. [21]... 

In 1989 we reported on the synthesis and structure of the first l,3-diphospha-2-sila-allylic anion 3a [4], mentioning its value as a precursor for phosphino-silaphosphenes. In analogy to 3a we obtained the anions 3b-f [5] by treatment of 4 equivalents of the lithium phosphide 1 with the adequately substituted RSiC, of which 3b and 3c were investigated by X-ray analyses. The very short P-Si bond lengths (2.11-2.13 A) of 3a-c and the almost planar arrangement of Pl-Sil-P2-Lil indicate the cr-character of the Lithium P-Si-P allyl complex. 

Once mineral-bound aluminum is recovered from ores, it forms metal complexes or chelates. Examples of the different forms of aluminum include aluminum oxide, aluminum chlorhydrate, aluminum hydroxide, aluminum chloride, aluminum lactate, aluminum phosphate, and aluminum nitrate. The metal itself is also used. With the exception of aluminum phosphide, the anionic component does not appear to influence toxicity, although it does appear to influence bioavailability. Aluminum phosphide, which is used as a pesticide, is more dangerous than the other forms however, this is because of the evolution of phosphine gas (a potent respiratory tract and systemic toxin) rather than to the exposure to aluminum. 

The chemistry of ruthenium and osmium bears little resemblance to that of iron except in compounds such as sulfideror phosphides, and in complexes with ligands such as CO, PR3, or A5-C5H5. The higher oxidation states, VI and VIII, are much more readily obtained than for iron and there is an extensive and important chemistry of the tetraoxides, M04, oxohalides and oxo anions. There are analogies between the chemistries of Ru, Os and Re especially in oxo, nitrogen and nitrido compounds. 

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