Nitride complex

Another type of osmium(VI) compound involving multiple bonds can be viewed as a derivative of OsN. The nitrides have attracted interest as they are often photoluminescent 

The Os=N group has a strong troni-influence, reflected in both the labiliza-tion of the franj-chloride (a similar reaction occurs with OsNBrs ) and in the pronounced lengthening of the rra 5-Os—Cl bond (2.605 A versus 2.362 A). 

With large organic cluster ions (e.g. Ph4As ) pink 5-coordinate OsNX (X = Cl, Br) is obtained. Red OSNI4 is made  

All the OSNX4 complexes are distorted square pyramids (with N—Os—X angles of 103.7 to 104.5°) [188]. The stability of an osmium(VI) to iodine bond is unusual and is presumably owing to the extensive OssN rr-bonding reducing the positive charge on the metal and stabilizing it to reduction. 

IR and structural data for these species are given in Table 1.15 [189]. 

---

A variety of routes is available for the preparation of metal-thionitrosyl complexes. The most common of these are (a) reaction of nitride complexes with a sulfur source, e.g., elemental sulfur, propylene sulfide or sulfur halides, (b) reaction of (NSC1)3 with transition-metal complexes, and (c) reaction of [SN]" salts with transition-metal complexes. An example of each of these approaches is given in Eq. 7.1,... 

The ligands that have been used in the preparation of metal nitride complexes are quite varied. They include halides, carbogenic groups (alkyl moiety and Cp ), pnic-togens (amine, amide, imide, phosphine, and arsine), and chalcogens (ether, alkox-ide, oxo, thioalkoxide, and selenides). Chart 1 provides a listing of the various ligands and the associated nitrido metal complexes. 

The reduction of MoVI nitrides with iodide has also been reported. As shown in Eq. (22), reaction of nitrido MoVI nitrides with MePh3PI afforded the corresponding Mov nitride complex 65 [30]. In a related process, treatment of a nitrido MoVI complex with sodium naphthalide leads not only to the Mov nitride but also to the formation of a Moiv2Mov2 (p-N)4 tetramer [31]. The structure of the latter product has been firmly established via single crystal X-ray crystallography. 

---