Structural studies of hexacoordinate silicon. Tris(o-phenylenedioxy) siliconate

P[N(iBu)CH2CH2]3N: A versatile non-ionic base for the synthesis of higher coordinate silicates

“…unit with two independent phosphatrane cations. The structural features of the silicate anion are similar to those in other catecholato silicates that contain different cations [12,17,[19][20][21], indicating that the phosphatrane cation did not exert significant structural influence on the dianion, although it is reported that the cations do influence the thermal stability of these higher coordinated silicates [10][11][12]. In the present case, an extended hydrogen bonding network, a prominent feature of hypervalent silicates with alkyl ammonium cations [10][11][12]15,16] was not observed, despite the presence of a P-H linkage in the azaphosphatranium cation.…”

“…Removal of solvents and subsequent washing with ether and pentane gave a colorless powdery solid in each case. The success of these reactions highlights the advantage of using a proazaphosphatrane as a superior base for the synthesis of hypervalent silicon compounds in terms of faster reaction time, ease of workup, higher yields, high purity and the anhydrous nature of the resultant silicates compared to those described in previous literature reports [17][18][19][20][21]. Ours is also the first example of a phosphine-assisted synthesis of higher coordinate silicates.…”

Crystal chemistry of six-coordinated silicon: a key to understanding the earth's deep interior

“…Single crystals of MnSiO3 garnet were first synthesized by Fujino, Momoi, Sawamoto & Kumazawa (1986), who determined the space group to be tetragonal (14~/a). Mn and Si atoms were found to be fully ordered in two symmetrically distinct octahedral sites (Table 11).…”

“…0 atoms are two-coordinated), thus leading to framework structures quite distinct in character from the high-pressure silicates of the earth's deep interior, all of which have O atoms in at least three coordination. Octahedral corner sharing also occurs in a variety of organic molecular crystals with [VUsi (see, for example, Flynn & Boer, 1969) and there are several dozen silicon-organic compounds for which [Wlsi occurs in aqueous solution (Liebau, 1985). Molecular crystals with six-coordinated silicon are not considered in this review.…”

Complexes of the Early Transition Metals with o-Mercaptophenol and 1,2-Dihydroxybenzene

“…It was argued that for complexes of Si(IV), containing water of crystallization, instead of the simple tris-chelated octahedral geometry, a structure like 4 would be observed (12). However a recent single crystal X-ray structure determination of the anhydrous (C,H6N),[Si(0,C6H4),] (C,H,N = pyridinium) complex (13) disproved the above postulate and established the occurrence of the tris-chelated octahedral geometry, a similar result was also obtained for a P(V) complex, [(C,H,),NH]-[P(02C6H4),] ((C,H,),NH = triethylammonium) (14). Whether the implications of these studies can be applied to complexes of the transition metals is not yet known since there is a total absence of structural work in this area.…”