Nitride chlorides

Many vinylogous amidinium salts, e.g. (185) and (186) (Scheme 25), are readily available by double formylation of CHa-acidic or alkenic compounds. Reviews on the chemistry of vinylogous amidinium salts are available. The first azavinylogous foimamidinium salt (187 Scheme 26) was prepared in 1960 by reaction of DMF with cyanuric chloride. The mechanism of this reaction has been estab-lished. Based on these findings new methods for the synthesis of these compounds were developed, e.g. the reaction of isocyanatomethyleneiminium salts with tertiary formamides affords salts (187). In the synthesis of the salts (187) cyanuric chloride can be replaced by phosphorus nitride chloride (PNCl2)3. ... 

CICN[g] CARBON NITRIDE CHLORIDE (GAS) 526 CrCI4[g] CHROMIUM TETRACHLORIDE (GAS) 564... 

Two tetrahedra with one common edge were first observed with Gd3NCl6 (Simon and Koehler 1986). From this nitride-chloride (Gd )3(N )(Cr)6, with the connection pattern [(Gd2/i Gd2/2)(N)]2Cl2Clg Cl272Cl Clg/3 one is directly led to such with linear chains of trans edge-connected [R4N] tetrahedra, analogous to the chains known from the structure of SiS2(anh-type). 

Zirconium nitride chloride ZrNCl has two polymorphs low-temperature a form with a FeOCl type layer structure and high-temperature 3 form with a CdBr2 type layer structure.The a form is very unstable to hydrolysis and easily attacked by moisture in air, whereas the 3 form used is stable even in water. A schematic structural model of 3-ZrNCl is shown in Figure 1. As seen from the figure, the zirconium... 

Zirconium nitride chloride was prepared by the reaction of zirconium tetrachloride with ammonia at elevated temperatures according to a similar method reported by Juza and Herners.The procedure was partly modified as follows zirconium tetrachloride purified by sublimation was placed in a quartz tube installed horizontally in an electric furnace. 

ThjZn,- or ThjNi,7-type 5.1.2. Nitride chlorides, bromides and ... 

Rare-earth nitride chlorides have been reported essentially for the early lanthanides and for yttrium with the three main stoichiometries R2NCI3 (R = La, Ce, Pr, Nd, Gd, Y), R3NCI6 (R = La, Ce, Gd) and RNCl where R=Ce, however a great richness of structural arrangements has already been found. 

All the crystal structures of the nitride chlorides have as a common feature that they contain N -centered tetrahedra, the electroneutrality of the compound being assured by the chlorine ligands. This dominating structural feature, underlined recently by Schleid (1996), is common to (oxy)nitride bromides and iodides and also to nitride sulfides and nitride sulfide chlorides. 

The borderline between cluster and valence compounds is clearly crossed with the scandium nitride chlorides which are unambiguously cluster compounds. Scandium shows here its difference in behavior, with compounds such as SC4CI6N, SC7CI12N (Hwu and Corbett 1986) or ScsClgN (Hwu et al. 1987), where nitrogen is an interstitial element. 

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