New Benzyl(β-oxido)phosphorus and -arsenic Ylides: Reactivity and Stereoselectivity in the Wittig Reaction
✍ Scribed by Dr. Benaissa Boubia; Dr. André Mann; Dr. François D. Bellamy; Dr. Charles Mioskowski
- Book ID
- 101559073
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 359 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0044-8249
No coin nor oath required. For personal study only.
✦ Synopsis
pendent paramagnetism of xmo, = + 1.77 x lo-, emu mol-'r61 is obtained. This result is in agreement with the magnetic properties of C~~Se.1'1
The Cu:Se ratio is 2: 1 in both 4 and Cu,Se. Heating 4 to above 160°C results in loss of PEt, and formation of a (previously) unknown phase, which, on further warming, transforms into p-Cu,Se (cubic). Cooling to below about 130 "C affords cr-Cu,Se (monoclinic).[sl Accordingly, 4 may be regarded as a molecular precursor for the formation of binary copper selenides. This is consistent with findings made by Steigerwald et al. on the formation of NiTe from [(cod),Ni] and Et,PTe. ['] Apparently, 4 and 5 are formed via a previously unknown and rather complex reaction path. Remarkably, however, 4 contains a Cu, unit (Fig. 3: Cu32-Cu36) whose structure is nearly identical with that of a Pd cluster of composition [Pd,As,(PPh,),]. This compound is formed on reaction of [PdCI,(PPh,),] with As(SiMe,), as part of a mixture also containing [Pd,oAs,,(PPh,),,], the Pd analogue of 5.14* l o ] Possibly, the nine-atom metal cluster is an intermediate in the condensation to very large clusters. Further examples of metal clusters containing a large number of metal atoms are [Au I s Ag I 9Br i 1 (PP-TOl, t 2 12@ > "i3sPt6 (CO),sH, -1 " ' >