Hapto compounds

The magnitude of the chemical shift anisotropy depends on the bonding situation and the nucleus gyromagnetic ratio. Since the bonds formed by lithium in organolithium compounds or other lithiated systems are mainly ionic, the anisotropy of the lithium chemical shift is generally small. It is more pronounced for Li than for Li. Li spectra are dominated by the quadrupolar effect and the CSA contribution to the Li lineshape is often negligible. Exceptions are compounds with poly-hapto bound lithium, such as... 

B. Diorganomagnesium Compounds Containing Multi-hapto-bonded... 

F. Donor-Acceptor Complexes of Diorganomagnesium Compounds with Multi-hapto-bonded Groups... 

Another type of ligand, capable of forming multi-hapto interactions with metals, are boron and boron-carbon cage compounds of which in particular the carboranes have been used extensively in organometallic chemistry . The structures in the solid state of a few magnesacarboranes have been determined by X-ray crystallographic studies. 

B. Diorganozinc Compounds Containing Multi-hapto Bonded Groups... 

The ligand-based chemistry and metal-ligand bonding of this class of ligand will be detailed in Chapter 7. However, by far the majority of compounds involving such ligands employ them as spectators rather than direct participants. A cyclic unsaturated ligand bound in an n-hapto manner, r n-CRn, provides VE to the electron count (Table 1.1). The... 

The hapto-type is used for organometallic compounds, where delocalized hydrocarbon systems are coordinated to a metal-center. Formally, there are no electrons assigned to the hapto-bonds, but the metal-center is included in the number of atoms, among which the delocalized electrons (and the charge, if present) are distributed. 

The uranium is hapto coordinated to the benzene and joined by two chlorine bridges to each AlCU unit. The coordination environment of the uranium is approximately a pentagonal bipyramid, considering the benzene to occupy only one site. The compound decomposes in polar solvents. 

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