Polyphosphide

The existence of a variety of other polyphosphide anions has been demonstrated. For example, P and P have been identified in LaP2 (72). Infinite chain stmctures for the polyphosphide anion have been reported for compounds such as KP and thallium pentaphosphide [11093-99-5] TIP. Cage anions such as P that include triply linked phosphoms atoms are found in Li P. ... 

Characterization of extended rnryunfm-polyphosphide clusters (p. 491) and polyphosphanes (p. 492). 

Figure 12.11 Schematic representation of the structures of polycyclic polyphosphide anions (open circles P, shaded circles P") (a) Pj ", (b) fPj Xr, (c) P8 i. (d) Pii -...

Recent extensive structural studies by X-ray crystallography and by P nmr spectroscopy have revealed an astonishing variety of con/imcto-polyphosphides with quasi-ionic... 

Polycyclic polyphosphanes are often best prepared by direct protonation of the corresponding polyphosphide anions (Figs. 12.11 and 12.12)... 

Examples of the anionic structures in polyphosphides, polyarsenides and poly antimonides. For comparison, recall the structures of red and black phosphorus and of arsenic (pp. 108, 109 and 110). Stereo image for NaPs... 

A number of binary phosphides and polyphosphides (compounds containing P—P bonds), for instance those of Mn, Tc, Re, Fe, Ru, Os can be prepared, often in well crystallized form, by the tin-flux technique. The mixture generally containing an excess of P (red P) and a high excess of tin is heated, possibly at a slow rate, to the required temperature (600°-1000°C) and maintained at that temperature for several days and then slowly cooled. In several cases the products may be recovered by dissolving the tin-rich residue in hydrochloric acid. The preparation of several ternary phosphides and of arsenides and antimonides has also been described (see 6.11.3). 

Preparation methods of phosphides and polyphosphides have been systematically described and discussed by von Schnering and Honle (1988). The following techniques and remarks, which are also of general interest, may be quoted. 

In the review by Kanatzidis et al. (2005), the preparation by the tin-flux method is mentioned also for several ternary phosphides and polyphosphides of rare-earth and transition metals. Typically the components (R metal, T metal, P and Sn in an atomic ratio of about 1 4 20 50) in sealed silica tubes were slowly heated, to avoid violent reactions, up to 800°C, annealed at that temperature for 1 week and slowly (2 K/h) cooled to ambient temperature. The tin-rich matrix was dissolved in diluted hydrochloric acid. The authors described the preparation of compounds corresponding for instance to the formula MeT4P12 (Me = heavy rare-earth metals and Th and U, T = Fe, Ru, etc.) and to the series of phases MeT2P2 (Me is a lanthanide or an actinide and T a late transition metal) having a structure related to the BaAl4 or ThCr2Si2 types. 

It may finally be mentioned that molecular beam methods have been used for the preparation of semiconductors as GaP and of thin films of higher polyphosphides. 

Figure I. Some homoatomic phosphorus units in metal polyphosphides as examples for polyanionic clusters.

Polyphosphide compounds within the scope of this overview rely heavily on contributions by von Schnering et al. (for a review on polyphosphides, see [86]), and major results concerning the heavier homologues As, Sb, and Bi are due to Rohr et ah, Eisenmann et al., and Belin et al. 

The J( Sn- Sn) values are less affected by the nature of the counter cation. Strong ion pairing has also been documented in the polyphosphide Zintl ions, such as LisPy [37]. 

From the pioneering work of Rudolph (group 14 Zintl ions) and Baudler (polyphosphide Zintl ions) to the modem multidimensional techniques used in current research, multinuclear NMR has played a central role in evaluating stmctures. 

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