Square-pyramidal geometry

X = F, Cl, and Br, contains the oxochromium(V) cation [23411-25-8], CrO ", exhibits a square pyramidal geometry. Compounds containing this cation are among the most stable Cr(V) compounds. 

SF4 is unusual in apparently acting both as an electron-pair acceptor and an electron-pair donor (amphoteric Lewis acid-base). Thus pyridine forms a stable 1 1 adduct C5H5NSF4 which presumably has a pseudooctahedral (square-pyramidal) geometry. Likewise CsF (at 125°) and Me4NF (at —20°) form CsSFs and [NMe4]+[SFs] (Fig. 15.21a). By contrast, SF4 behaves as a donor to form 1 1 adducts with many Lewis acids the stability decreases in the sequence SbFs > AsFs > IrFs > BF3 > PF5 > ASF3. In view of the discussion on... 

In nickel and palladium dithiobenzoato complexes, four-membered chelate rings are formed (366), whereas, in the corresponding phenyl-dithio acetates [M2(S2CCH2Ph)4], the dithio ligands act as bridging groups between the two metal atoms, with the formation of binuclear units (367). The molecular structure of the latter compounds shows that each metal atom is coordinated to four sulfur atoms and to the other metal atoms in a square-pyramidal geometry. Other evidence for... 

Additional results indicate that the formation of (XV) is the result of the fact that S-coordinate Ir(III) complexes prefer a square-pyramidal geometry with the vacant octahedral site trans to the most strongly trani-labilizing ligand (COEt) [R. J. Mawby, private communication (March 1972)]. 

The square pyramidal geometry of CIF5 completes our inventory of molecular shapes. Figure 9-26 summarizes the characteristics of atoms with steric number 6. 

With its empty 3 d orbitals, SF4 also acts as a Lewis acid. This molecule forms adducts with pyridine and with fluoride ion. Each adduct has square pyramidal geometry, with a lone pair of electrons completing an octahedral... 

The dark red Ir11 binuclear complex [Ir(CO)(P(/i-tolyl)3)(mnt)]2, formed via one-electron oxidation of [Ir(CO)(P(/ -tolyl)3(mnt)] by ferrocenium, contains chelating mnt ligands bridging the Ir—Ir bond.639 The X-ray crystal structure shows square-pyramidal geometry at each Ir, and an Ir—Ir bond length of 2.706(2) A. 

The square-planar Ir1 thiolate complex (391) has been prepared by the reaction of Pr(NO)Cl2(PPh3)2] with NaSmes (mes = C6H2Me3-2,4,6).635 reaction of (391) with propylene sulfide affords the Ir111 complex (392), as shown in Reaction Scheme 42. The X-ray structure of (392) confirms the square-pyramidal geometry of the Ir center and the bent nature of the Ir—N=0 linkage. 

With P-donors a variety of different structures are formed. Two complexes (359a,b) with a five-coordinate square pyramidal geometry and one S-donor in the apical position are reported.934,933 In a related complex (360) the nickel center reveals a distorted square planar geometry, because one xanthate ligand switched to a monodentate coordination mode. 6 By reaction of [NiL2] complexes with Ph2P(CH2)2P(Ph)(CH2)2PPh2, compound (362) is formed, which consists of a five-coordinate cation and a hexacoordinate anion. 7... 

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