Octamethylpyrophosphoramide complexes

Octamethylpyrophosphoramide (ompa) has been shown to loosen ion pairs in solution178 and a 1 3 complex has been isolated with Mg(C104)2. The crystal structure shows that the ligand is bidentate and chelates to the cation through the phosphine oxide oxygens.179... 

Nephelauxetic parameter (ft) and SINHA s covalency parameter of (6) for the HMPA-complexes of the lanthanides, and a comparison with other complexes containing P -> O donor ligands. TBP = tributylphosphate, OMPA = octamethylpyrophosphoramide, HMPA = hexamethylpyhosphoramide. To emphasize the weak nephelauxetic effect produced by the P-0 donor ligands, some of the fi and S values are expressed with three or four places after the decimal without rounding off. Ref. [290]. 

Studies of the complex chemistry of the tervalent lanthanides show that coordination numbers higher than six are common, for example in the tetrakistropolonates 79), the complexes of the perchlorates with N,N-dimethylacetamide (DMA) (77) or octamethylpyrophosphoramide 61), of the iodides with N,IV-dimethylformamide (DMF) (76), the nitrates with triphenylphosphine (or arsine) oxide 46), and the -diketone... 

Complexes of Rare Earth Ions with Octamethylpyrophosphoramide... 

TJrevious work in this laboratory (5, 6, 14) has demonstrated the ver-- satility of octamethylpyrophosphoramide (OMPA) as a ligand. Stable complexes of OMPA... 

The rare earth complexes of octamethylpyrophosphoramide are the first examples of isolated complexes with rare earth ions coordinated to the pyrophosphate linkage. Experimental evidence supports the coordination of the phosphoryl oxygens to the metal ion with additional coordination positions occupied by water. 

Octamethylpyrophosphoramide, OMPA, (Me2N)2P(0)-0-P(0)(NMe2)2, is obtained if dimethyl-amine is used in place of ammonia in reaction (7.73). This colourless hygroscopic and very toxic compound has a melting point of 20°C and is ether-soluble. It can be distilled without decomposition and it is an effective insecticide if first absorbed by plants (Chapter 12.12). It is capable of forming numerous phosphoryl coordination complexes as, for example, Co(OMPA)3 CIO4, Cu(OMPA)2 CuCU, Fe(OMPA)3 (FeCUs. 

Few stable complexes of alkali metals have been reported. Complexes of the alkali metals with j -diketone derivaties, o-nitrophenol, and sali-cylaldehyde have been described in the literature.The sodium compounds ranged from hydrated ionic salts such as Na (acac)-2 H2O to adducts like Na(Sal) HSal (HSal = Salicylaldehyde). PfeiflFer and others have reported the isolation of a complex of sodium perchlorate with 1,10-phenan-throline. Brady and Badger have presented evidence for chelation in sodium salts of o-hydroxybenzaldehydes. More recently, Popp and Joesten have isolated and characterized a number of alkali metal and alkaline earth metal salts with the ligand octamethylpyrophosphoramide (OMPA). Gentile and co-workers have also reported complexes of diacetamide with alkali and alkaline earth metal salts. 

---