Zn-X bonds

The broken bonds (boldface = dissociated fragment) BDEs (boldface = recommended data reference in parentheses) kcal/mol kj/mol Methods (reference in parentheses) References 

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In order to study the effect of disorder between two atoms, single crystals composed of pairs of the complexes [TpBut]ZnCl, [TpBut]ZnI, and [TpBut]ZnMe, over a range of compositions, were studied. In each case, only a single atom was observed at the disordered site, and the Zn-X bond length that was measured corresponded to a composite for the... 

Fig. 10. The three best COSMOS-NMR force field results of a peptide-zinc complex obtained with NOE as well as chemical shift pseudo-forces. Zn-X bonds are shown if the distance is shorter than 2.5 A. The force field search for the most stable complex was run with a free Ziv ion.

The reactivity of three-coordinate [BpBut]ZnR is summarized in Scheme 12. The Zn-C bonds of [BpBut]ZnR are readily cleaved by H20 and MeC02H to give the hydroxo and acetato complexes [BpBut]Zn(/i-OH) 3 and [BpBut]Zn(7j2-02CMe), respectively. The structure of [BpBut]Zn(/u-OH) 3, determined by x-ray diffraction, is a cyclic trimer, with Zn-OH bond lengths in the range 1.89-1.99 A (Fig. 29). The... 

The structure of [TpBut Me]ZnOH has been determined by x-ray diffraction, confirming the presence of a terminal zinc hydroxide functionality, with a Zn-OH bond length of 1.850(8) A (Fig. 40). The Zn-OH moiety has also been characterized by a variety of spectroscopic techniques, including IR, 1H, 2H, and 170 NMR spectroscopies, as summarized in Table VI. For example, the H NMR spectrum of [TpBut,Me]ZnOH, shown in Fig. 41, illustrates that the [Zn-OH] moiety is observed as a sharp signal at 8 - 0.07 ppm in C6D6. The importance of using a sterically... 

The X-ray structure of zinc naphthalocyanate has been determined with Zn—N bond lengths of 1.983(4) A.829 Pentanuclear complexes with a zinc phthalocyanine core and four ruthenium subunits linked via a terpyridyl ligand demonstrate interaction between the photoactive and the redox active components of the molecule. The absorbance and fluorescence spectra showed considerable variation with the ruthenium subunits in place.830 Tetra-t-butylphthalocyaninato zinc coordinated by nitroxide radicals form excited-state phthalocyanine complexes and have been studied by time-resolved electron paramagnetic resonance.831... 

Chelating aldehydes such as 2-pyridine carbaldehyde and 2-dimethylamino benzaldehyde improve the stability of the aldehyde complexes via N,0 chelation. NMR studies show that the complexes are present in solution without an excess of aldehyde and can be formed in the presence of donor ligands. The X-ray structures showed longer and weaker Zn—O bonds when more than one chelating ligand was present. IR demonstrates the variation in C=0 bond strengths and how the environment of the zinc ion will influence potential catalytic activity via reaction rates or pathways. Tetrahedral chelate complexes, and octahedral bis- and tris-chelate complexes, were isolated.843... 

Acetylacetone was deprotonated with diethylzinc in toluene to afford [EtZn(acac)]2 (Figure 65, 140) which crystallized in dimeric form. The quality of the X-ray data was too low to obtain reliable bond parameters, but the coordination environment about zinc is distorted tetrahedral, with two intramolecular and one intermolecular Zn-O bond.200... 

An X-ray crystal structure determination of the [f-Bu3Zn] anion present in 21 has an almost perfect trigonal planar arrangement [Zn—C bond distances 2.080(7), 2.059(7) and 2.057(8) A C-Zn-C angles 118.1(2), 120.7(3) and 120.6(3)°]. Compound 21 was prepared by reacting l,3,4,6,7,8-hexahydro-2//-pyrimido[l,2]pyrimidine, Me2Zn and f-BuLi (equation 9). It is notable that the methyl groups initially bound to zinc all become... 

The structures of 39, 42 °, 43 ° and 44 in the solid state were determined by X-ray crystal structure determinations. The Zn—C bond distances and angles in these compounds are comparable (Table 3). As a representative example the structure of 39 is shown in Figure 20. 

The X-ray crystal structure determination of bis[2,2,4,4,6,6-hexamethyl-2,4,6-trisilacy-clohexyljzinc (45) shows that this compound exists as a monomer in the solid state (Figure 22). The observed Zn—C bond distance of 1.937(2) A is remarkably short. The zinc atom is located at a crystallographic inversion centre and consequently enforces a perfectly linear C—Zn—C arrangement. The Zn—C(l)—Si and Si—C—Si bond angles of 110 and 117°, respectively, indicate that a considerable planarization of C(l) has occurred. That such a planarization of the carbon atoms bound to zinc is most likely also present in the structure of 45 in solution was concluded from their exceptional low field shift of 13 ppm and the small J( C- H) and 7( C- Si) coupling constants observed in its C NMR spectrum. 

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