Bonds dative

It should be noted that dative bonds, like metal complexes and charge transfer species, in general have RHF wave functions which dissociate correctly, and the equilibrium bond lengths in these cases are normally too long. 

The HF wave funetion eontains equal amounts of ionie and eovalent eontributions (Section 4.3), For covalently bonded systems, like H2O, the HF wave funetion is too ionie, and the effect of electron correlation is to increase the covalent contribution. Since the ionic dissociation limit is higher in energy than the covalent, the effect is that the equiUbrium bond length increases when correlation methods are used. For dative bonds, such as metal-ligand compounds, the situation is reversed. In this case the HF wave function dissociates correctly, and bond lengths are normally too long. Inclusion of... 

With one dative bond from carbonyl and n = 1.67, the average bond angle for Fe(CO)3 is predicted from Eq. 1 to have the value 94.5°. Most of the numerous experimental values lie within about 2° of this value, and their average, 95.6°, with mean deviation 1.2° (Table 2), is in acceptable agreement with it. 

Additional computational studies [16] provided detailed information about the nature of the dative bond, the strength of the acid-base interaction and the... 

The only structurally characterized In—Sb adduct is (Me3SiCH2)3 In—Sb(Tms)3 19 [38], featuring an In—Sb bond distance of 300.8(1) pm. Due to the lack of other structurally characterized In—Sb adducts, no structural comparisons can be made. The In—Sb bond length found in 19 is supposed to be at the lower end of the In—Sb dative bond range since the covalent radius of In (r ov 143 pm) is about 17 pm larger than those of the lighter elements Al and Ga. Therefore, In—Sb dative bonds are expected to... 

The two selenium atoms are attached to the low-coordinated phosphorus atom, with two lengthened dative bonds (2.788 and 2.637 A). Interestingly the phosphorus atom is here strongly pyramidalized, the Z SePSe angle was 80.6°. In other words the lone pair orbital at the electrophilic phosphorus atom remains stereo chemically active, as one would expect on the basis of the quantum chemical theory of bonding within this species. 

The N—>P dative bonds are weak and different in lengths (1.800 A on average), and the triflate anions are effectively extended to consider interaction with the counter ion. Again the phosphorus atom is strongly pyramidalized and features the aspects of an inert nonbonding electron pair. 

The existence of a Pd° >Mo" dative bond elongates the quadruple Mo2 bond to some extent. This complex has two Pd° centers that can react with a variety of olefinic compounds, shown schematically in Figure 111 such reactions give Mo2Pd2(pyphos)4(L)2 [L = acrylonitrile, fumar-onitrile, tetracyanoethylene] in moderate yields. Unlike the previous compounds which have a strictly trans arrangement of the P-donor atoms, the last compound has a cis arrangement and thus the four metals are not linear.959... 

We should note that the formation of this bond confers formal charges on the B and N atoms. In this bond and many similar Lewis acid-base complexes both the electrons forming the bond come from the same atom rather than from different atoms, as in the formation of a bond between two chlorine atoms. This type of bond is often called a donor-acceptor bond, a dative bond, or a coordinate bond, and is sometimes given a special symbol—an arrow denoting the direction in which the electron pair is donated ... 

In the hydrolysis of neutral tricyclic hexacoordinate spirophosphorane 143 with internal N—>P dative bonds, the six-membered phosphorinane ring is retained during the first stage of hydrolysis. Five-, seven-, and eight-membered rings were preferentially hydrolysed (Equation 4) <1998POL3643>. 

Hexacoordinate spirocyclic phosphorus compounds have been prepared in which the spirocyclic system involves dative bonds from the dimethylamino-l-naphthyl ligand <1996JOM173, 1997PS181, 1999IC1336> for example 113 (Equation 29). Spirophosphoranide 122 was synthesized by deprotonation of the acid precursor 121 with triethyl-amine (Equation 30) <2001IC6229, 2002IC1645>. 

Thiol-containing molecules can interact with metal ions and metal surfaces to form dative bonds. Dative bonds also are known as coordinate covalent bonds. They differ from normal... 

Figure 2.2 A number of small thiol-containing molecules have proven useful for modification of gold or metallic surfaces. The dithiol derivatives provide better dative bond stability and can t be displaced easily by competing thiols or oxidation. Most thiol-containing compounds used for surface modification also contain terminal functional groups or reactive groups for coupling affinity ligands.

Figure 9.60 Many different thiol-containing linkers can be used to prepare water-soluble QDs. The monothiol compounds suffer from the deficiency of being easily oxidized or displaced off the surface, thus creating holes for potential nonspecific binding. The dithiol linkers are superior in this regard, as they form highly stable dative bonds with the semiconductor metal surface that do not get displaced. The PEG-based linkers are especially effective at creating a biocompatible surface for conjugation with biomolecules.

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