Tridens

In view of the excellent donor properties of tertiary arsines, it is of interest to inquire whether these cyc/o-polyarsanes can also act as ligands. Indeed, (MeAs)s can displace CO from metal carbonyls to form complexes in which it behaves as a uni-, bi- or triden-tate ligand. For example, direct reaction of (MeAs)5 with M(CO)6 in benzene at 170° (M = Cr, Mo, W) yielded red crystalline compounds [M(CO)3( -As5Me5)] for which the structure... 

In our earlier efforts to synthesize dendritic amphiphiles, we described a triden-dron (43) which was prepared by a two-step (alkylation-amidation or triester-tris) reaction sequence applied to l,3,5-tris(bromomethyl)benzene [117]. TEM and light scattering experiments suggested that 43 aggregated by stacking of its hydrophilic exterior into a spherical array of ca. 20 nm (diameter) reminiscent of globular micelles. 

Die Boride zeigen also einerseits groBe Ahnlichkeiten mit den Ni-triden und Karbiden. Sie unterscheiden sich jedoch von diesen durch die groBe Tendenz der Boratome, Bor— Bbr-Bindungen auszubilden und zeigen darin eine Verwandtschaft mit den Siliziden, die im nachsten Ab-schnitt besprochen werden. 

Table 9 Linear Tridentate Polyamine Ligand Configurations in M(triden-...

Optical RecordingDyes (seeChapter 6). Mixtures of the nicke 1-complexed triden-tate formazans 50 are claimed to provide good light stability to optical recording layers and elements [87],... 

The rapid allocation of trace quantities of to external AM fungal hyphae provides independent support for the observations by Johnson et al. (2002a, b) that carbon transfer to mycorrhizas occurs very quickly. Staddon et al. (2003b) concluded that the turnover rate of AMF hyphae was likely to be just 5-6 days. This corresponds well with the turnover rates by absorptive hyphal structures of 5-7 days observed in Artemisia triden-tata and Oryzopsis hymenoides communities (Friese Allen, 1991). However, it is not known from the Staddon et al. (2003b) study if the carbon allocated to the AMF was used for production of mycelial biomass or allocated into compounds that are rapidly respired, in accordance with the observations of Johnson et al. (2002a, b). 

Zehnder, Inorg. Chem., 31, 4194 (1992). Transition Metal Complexes of the Novel Triden-tate Di-2-pyridylmethanamine (dipa). 

UMoi2042(Er-(H20)5)2] nH20 and (NH4)3[UThMoi2042]," " [UMoi2042] serves as a triden-tate ligand towards the other metal centers. 

There is no established, quantitative correlation between the contact shifts and the structure of the complex. However, it was observed that, for triden-... 

Highly enantioselective reduction of simple aliphatic ketones is difficult to achieve. However, when a Ru catalyst is prepared from [RuCl2(CgHg)]2, triden-tate ligand 25, and a base, reduction of pinacolone in 2-propanol occurs at room temperature to give a chiral alcohol in 92% ee and 85% yield (Scheme 34) [119]. 

An attempt to prepare triorganoantimony compounds containing triden-tate ligands failed as a result of their spontaneous decomposition to triorganostibenes R3Sb and 2-acetyl-3-methyl-4//-1,4-benzothiazine (106).148... 

The compound [Li(Tp )(Hpz )]-Hpz is the unique reported lithium compound, structurally characterized, containing a homoscorpionate ligand. It shows a UN4 distorted tetrahedral geometry with a triden-tate Tp (Fig. 2.1). The crystal packing is dominated by hydrophobic methyl-methyl interactions.1... 

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