Arsane

Molecular Clusters of Dimetalated Primary Phosphanes and Arsanes Matthias Driess... 

MOLECULAR CLUSTERS OF DIMETALATED PRIMARY PHOSPHANES AND ARSANES... 

Reaction of the phosphane la and the arsane 2a with freshly sublimed BuLi in the molar ratio of 1 2 in toluene as solvent at —80°C... 

The synthesis of crystalline disodium derivatives of primary phos-phanes and arsanes turned out to be more difficult than that of dilithium compounds. The reaction of NaN(SiMe3)2 with 2c led, as in its lithiation with BuLi, under redox reaction (H2 elimination, As-As bond formation) to the Na2As6 dimer 12 (Eq. 5). The latter has been... 

Instead of giving a comprehensive summary on M-E and E-E distances (M = Li, Na E = P, As) for the compounds discussed earlier, this section mainly presents considerable structural features. A comprehensive discussion of the characteristic structural aspects of main group metalated phosphanes and arsanes has been published in an excellent review (2). 

A facile method to form M-P and M-As bonds (M = Al, Ga, In) is represented by the reaction of primary phosphanes and arsanes with E-H containing organometal reagents, which takes place with elimination of H2. Thus, stepwise reaction of iBu2A1H with the primary... 

An important result of the multinuclear NMR investigations of 23— 25, 27, 28, and 31-35 is that the structures, in contrast to aggregates of monometalated secondary phosphanes and arsanes, are retained in solution. Thus, the phosphandiide derivatives here discussed show resonance signals in their 31P NMR spectra that are independent of concentration and temperature (see Table III). The 31P and 27A1 NMR chemical shifts of 23-25, 27, and 31-35 differ with respect to ring size of the clusters and electronic influences by the substituents at phosphorus and aluminum. 

The structure of 32 (62) is remarkable since it possesses, at the same time, three- and four-coordinated Ga centers (Fig. 26), whereas 28 represents the first example of a partially metalated arsane-... 

A convenient route to andiides, where Li and A1 centers are, at the same time, involved is represented by the reaction of LiAlH4 with primary silylphosphanes and silylarsanes (Scheme 4) (67). However, the outcome of such reactions is dependent on the stoichiometry. The silylarsane 2c reacts with LiAlH4 in the molar ratio of 4 1 in 1,2-dimethoxyethane, under evolution of H2, resulting in the corresponding tetrakis(arsaneyl)-substituted lithium alanate 36c in quantitative yield. The similar transformation of the arsane 2a with LiAlH4 in the... 

In summary, the solubility and the degree of aggregation of dimeta-lated phosphanes and arsanes can be controlled by employing appropriate lipophilic substituents at phosphorus and arsenic. Triorganosi-lyl substituents fulfill this requirement especially well. The tendency... 

Over the past few years, a large number of novel and fascinating classes of meta-lated phosphanes and arsanes with group 1, 2, 3 and 4 metals have been developed. The purpose of this survey is to present the main structural features thereof. 

The metalation of trialkylsilylphosphane and -arsane with the alkaline earth metal bis[bis(trimethylsilyl)amides] of calcium, strontium, and barium yields the mixed phosphanides and phosphanediides as well as arsanides and arsanediides depending on the stoichiometry and the demand of the trialkylsily] substituents according to Scheme 3.6-11. The main feature is the M2E3 bipyramid with the metal atoms in apical positions. These cages are often interconnected via common faces (61, 63, 64, 65, 67, and 69). A substitution of the phosphanide substituents by other Lewis bases such as THF or benzonitrile is not possible for these compounds and, consequently, homoleptic phosphanediides and arsanediides with inner M4E4 heterocubane moieties are so far unknown for M = Ca, Sr, and Ba. In all these cases a further metalation to obtain homoleptic phosphanediides failed. 

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