Linear Trimeric Hafnium Clusters in Hf 0
The reduction of hafnium tetraiodide, HfI4, with aluminum at 600 °C or 850 °C in the presence of a NaI flux resulted in black single crystals of Hf0.86(1)I3. This composition corresponds well to the upper end of the non-stoichiometry range 0.89 ≤ x ≤ 1.00 previously reported for HfxI3. The crystal structure (a = 1250.3(2), c = 1999.6(3) pm, R-3m, Z = 18) is made up of hexagonal closest packed layers of iodide ions. One third of the octahedral holes would be filled as in TiI3 or ZrI3 if it were Hf1.00I3. In Hf0.86(1)I3, one out of six octahedral holes along [001] are, however, only occupied by 16%. In contrast to TiI3-I and ZrI3, one striking structural feature is in the formation of linear hafnium trimers with identical Hf―Hf distances of 318.3(2) pm rather than the formation of dimers. These may be associated with Hf―Hf bonding although only 2.64 electrons are available for one Hf5.16I18 column.
Kristallstruktur von Zirkoniumtetrajodid ZrI4: ein neuer AB4‐strukturtyp
The crystal structure of ZrI 4 was determined from Xray diffractometer data and was refined by full-matrix least-squares methods to an R index of 0-045 for 1985 observed reflexions. The crystals are monoclinic, space group P2/c with a = 8.356 (2), b = 8.326 (2), c = 17.926 (4) A, fl = 103.21 (3) ° , V = 1214. I A 3, D x = 4.914 Mg m -3, Z = 6 ZrI 4. The structure consists of infinite chains of ZrI 6 octahedra sharing non-opposite edges in such a way that a helical arrangement with an identity period of six octahedra along the chain results. It appears to be the first AB 4 structure of its type, different from the ct-NbI 4, ZrCI4, and fl-ReCl 4 chain structures. Z r I distances range from 2 . 6 9 2 ( 1 ) t o 3.030 (1) A, Z r Z r separations along the chains are 0567-7408/79/020274-05501.00 uniform [4.394 (1) and 4.416 (1) AI; I I distances within the c.c.p, anion arrangement are 3 .8994.199 (1) A within the chains and 4.103-4.413 (1) A between the chains.
Catalytic removal of tert-butyldimethylsilyl (TBS) ether by PVP-I
Abstract A mild, efficient and rapid protocol the deprotection of alcoholic TBDMS ethers using PVP-1 as catalyst in methanol, the procedure of deprotection of various TBDMS ethers were found to be very convenient, easy work-up, high yielding.