Organometallic complexes, salt

The selective insertion of diphenylacetylene in the cyciopaiiadated sulfide complex 1 leads to the stable organometallic complex 2, which can be depalladated with silver(I) tetrafluoroborate to give a mixture of the dibenzothiepinium salt 3 and the dibenzo[Z>,z ]thiepin 4.91 Demethyla-tion of 3 to yield 4 is complete after refluxing overnight in chlorobenzene. The synthetic scope of this method for thiepin derivatives is limited due to their thermal instability, but the method is very suitable for the synthesis of 1//-2-benzothiopyrans.91... 

Scheme 11). Alternatively the quaternary salts can be converted thermally into acyliron chelate complexes which can then be oxidized to azetidinones (Scheme 12). Extension of the method to the synthesis of a condensed azetidinone is illustrated in Scheme 13, but the scope of the procedure has not been evaluated. It will also be of interest to assess the utility of other cationic organometallic complexes preliminary studies have shown that molybdenum complexes behave in an analogous manner but the oxidative cyclization is inefficient (Scheme 14). 

Cafionic photoinitiation is based on the ring opening of the oxirane group. The photoinitiators of practical importance belong to three main classes of compounds diazonium salts, onium (e.g., iodonium and sulfonium) salts, and organometallic complexes, which upon irradiation by UV light decompose and yield an acid catalyst. 

Chemical routes involving the use of tungsten salts have been reported. W2C was claimed to be formed by the pyrolysis of an organometallic complex containing cyclopentadiene and carbonyl groups.8 The W2C formed was useful for ceramic applications such as wear resistant surfaces and cutting tools. The same phase was also prepared by the reduction of WC14 with sodium triethylborohydride.9 The material was formed as 1-5 nm-sized crystallites as shown by SEM and TEM. 

Eisenberg and co-workers (135-137) investigated dithiolene-containing organometallic complexes of Rh and Ir. Addition of an alkyl halide to [Rh(CO)-(PPh3)(mnt) forms a Rh(III) halo acyl complex. The halide can be stripped off by Ag+ salts (135) (Eqs. 30 and 31). 

---