Bioctahedral units

Each phosphate group provides an oxygen atom to bridge the vanadium sites of the confacial bioctahedral unit. Of the remaining three oxygen atoms, one is deployed as a donor to a neighboring comer-sharing binuclear unit and two link... 

M(OR)5 compounds are known to be monomeric or dimeric. Examples of the latter include [Nb(OMe)5]2203 and [U(OBut)s]22(M which have edge-shared octahedral M2O10 units (Figure 1). An interesting example of a mixed valence compound of U4+ and U5+, U2(OBu )9, has been found to have a confacial bioctahedral U209 moiety.204 In both [U(OBu )5]2 and U2(OBu )9, the long U---TJ distances, ca. 3.5 A, preclude any direct metal-metal bonding. 1... 

Type II bioctahedral molybdate unit [Cu(phen)(M02O5)(H2O)(O3PCH2PO3)] 1-D CuN203 Trinuclear unit (Mo205)(03PCH2P03) K2K-... 

The structure of the mixed hydroxo-alkoxide species consists of two face-sharing bioctahedral Zr2X9 units each bound to Ba2+ by four X groups. Recent studies28 have shown that for the system Al(OPr )3—M(OPr )4, M = Zr and Hf, in isopropanol there is only one type of complex formed, namely, [(OPr )2Al(p,-OPr )2]2M(OPr )2. A rare heterotermetallic alkoxide which contains Cd, Ba, and Zr has been prepared29 according to... 

SbCLt, square pyramidal SbCls ", and octahedral SbCle ". The successive additions of Cl are made trans to Cl in pyramidal SbCls, probably, using the vacant Sb-Cl a orbital as acceptor orbital. The resulting Cl-Sb-Cl units can be treated as 3 center, 4 electron systems. Octahedral coordination is also observed in the bifacial bioctahedral anions Sb2Cl9 (8). ... 

Just as the confacial bioctahedral dimer [TijXj] " provides the structural unit that is reproduced to form the j6-TiClj polymer chain, so [TijCl ] " and [TijCl,]" are the building blocks for the [TijClj j] and [TijCl j g] " complex anions prepared from redox reactions involving Pt(PPhj)j and TiCl Physical properties of these mixed Ti(III)/Ti(IV) anions suggest triple chloride bridges. The possibility of metal-metal interactions exists, but structures are not available. 

Conproportionation of ReCls and ReCls in a sealed tube at 300-600°C yields jS-ReCU containing dimeric confacial bioctahedral M2X9, units that share terminal chlorides as indicated by [Re2(/i-Cl3)Cl4]Cl2/2. Other routes to ReCU include heating Reds above 350 C under an N2 stream and hydrolyzing ReCU to Re02 prior to refluxing in thionyl chloride . In contrast to ReCU, the TcCU structure excludes metal-metal bonding. ... 

Fig. 43. (Top) Projected DOS for the Gd,oCI,8C4 unit with the Gd projection shaded (left) and C2 projection (middle the energy scheme for two free C2 units is also presented (right) the Fermi level is indicated by the dotted line. (Bottom) Representation of the Gd-Gd bonding orbital above the Fermi level marked by the arrow the orbital is drawn in the plane of the Gdi(, bioctahedral base (Gd circles Cl points).

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