Metal phosphites

The water elimination reactions of Co3(P04)2 8 H20 [838], zirconium phosphate [839] and both acid and basic gallium phosphates [840] are too complicated to make kinetic studies of more than empirical value. The decomposition of the double salt, Na3NiP3O10 12 H20 has been shown [593] to obey a composite rate equation comprised of two processes, one purely chemical and the other involving diffusion control, for which E = 38 and 49 kJ mole-1, respectively. There has been a thermodynamic study of CeP04 vaporization [841]. Decomposition of metal phosphites [842] involves oxidation and anion reorganization. 

Nagoumey and Madan [20] have considered both AAS and ICP-AES as reliable measurement techniques for the determination of metal components in mixed-metal/phosphite stabiliser systems in PVC. For reasons given elsewhere (Section 8.3.2.4), in this case ICP-AES was considered the technique of choice for most metal stabiliser determinations, while AAS remains a useful method to corroborate the ICP-AES results. For the determination of tin in rigid PVC by means of HG-AAS, the main effort has been to develop a sample digestion procedure [118]. Tin and Ti from a PVC potable... 

IV.30 PHOSPHITES, HPO Solubility The phosphites of the alkali metals are soluble in water all other metallic phosphites are insoluble in water. 

Brill, T. B., Landon, S. J. Arbuzov-like dealkylation reactions of transition-metal-phosphite complexes. Chem. Rev. 1984, 84, 577-585. 

Alkali metal phosphite derivatives (RO)2P-OM are obtained from dialkyl H-phosphonates in two ways. The first one includes reaction of dialkyl H-phosphonates with alkali metals, usually in the presence of inert organic solvents such as diethyl ether or THF. 

Whilst almost all metals are included here in the treatment of metal phosphides (Sections 8.1 through 8.7), the treatment of metallophosphorus coordination complexes (Sections 8.9 through 8.20) deals mostly with transition metals. The discussion of metal phosphines and metal phosphites (Section 8.8) is largely confined to metals from Groups I through in while compounds with p-block metals are dealt with in Chapter 9 (Eigure 8.1). 

Ligand metallation. In early transition metal polymerization catalysis often metalation of the ligand occurs leading to inactive catalysts. In late transition metal chemistry the same reactions occur, but now the complexes formed represent a dormant site and catalyst activity can often be restored. Work-up of rhodium-phosphite catalyst solutions after hydroformylation often shows partial formation of metallated species, especially when bulky phosphites are used [50]. Dihydrogen elimination or alkane elimination may lead to the metallated complex. The reaction is reversible for rhodium and thus the metallated species could function as a stabilized form of rhodium during a catalyst recycle. Many metallated phosphite complexes have been reported, but we mention only two, one for triphenyl phosphite and rhodium [51, 52] (see Figure 19) and one for a bulky phosphite and iridium [53]. 

Phosphites. The deprotonation of (7,0-dialky 1 phosphites (25) with KH or NaH generates metal phosphites (26), which can be reacted with CS2 followed by the reaction with alkyl halides to afford (7, (3-dialkyl phosphonodithioformates (27) (eq 18). The deprotonation with JCH is carried out at 0 °C for 3 h, whereas the reaction withNaH is performedinTHFatrefluxforS min. As alkyl halides, methyl iodide, trityl, fluorenyl, and benzyl bromides are used, and the products (27) are obtained in 65-85% yields. 

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