Solid Trident

L = C3H3, C H ) and then [Rh(acac)(CO),] to yield the tetranuclear species 180 (85ICA(i00)L5), where the heterocyclic ligands are tridentate. The product reacts with the rhodium(I) dimer [Rh(CO)2Cl]3 to give the trinuclear complex 181. In the solid state, the molecules of this complex form the intermolecular stacks along the z-axis. 

The synthesis of the first quadruply bonded tungsten(II) car-boxylate, W2(02CCF3)4 (hereafter referred to as V TFA) ), was reported by us last year (1). The structure of its diglyme adduct, W2(TFA)4 2/3 diglyme is shown in Figure 1. This particular view shows the partial contents of two unit cells and it emphasizes the tridentate nature of the axially coordinated polyether which "stiches" W2(TFA) units together in the solid state. We now have in hand several other adducts of W2(TFA) and one of these, W2(TFA)4 2PPh3 (an axial adduct), has been structurally characterized (2). Despite many attempts, X-ray quality crystals of unsolvated W2(TFA) have not been obtained. 

Recently, the crystal structure of a nickel(II) complex with a tridentate silyl ligand has been reported [20]. The structure in the solid state shows an //2-(Si-H) binding to nickel, with a Ni-H distance of 1.47 A NMR spectra of the complex in solution at -80 °C suggest the formation of a nickel(IV) hydride species through oxidative addition of the silyl-hydrogen to nickel [20]. 

Ai,Ai -Diphenylbenzamidine undergoes metaUation in toluene, the crystalline precipitate (232) is probably polymeric and contains solvating toluene (average 0.7 mol per Li atom). The lithium imidinate solid produced in the presence of HMPA is dimeric (233) whereas the solids obtained in the presence of bidentate and tridentate ligands (e.g. TMEDA and PMDTA) are monomeric (234 and 235). The products were characterized by H NMR spectra and XRD crystallography, except for 232, for which no crystals suitable for XRD could be prepared . 

Fig.6 The organo-platinum(II) complex containing N,C,N tridentate ligands reversibly binds gaseous SO2 in the solid state. The reversible reaction occurs at the Pt(ll) complex by Pt-S bond formation and cleavage. Uptake and release of SO2 does not destroy the crystalline ordering... 

Figure 6.11 Typical tridentate ligand structure incorporating a chiral amino alcohol and modified diamine-based tridentate ligand structure attached to the solid support for parallel catalyst library strategy.

CIS-VO2 complexes with tridentate Schiff-base ligands also appear, and they sometimes have five-coordinate square-pyramidal structures with one oxo-ligand at the apex. Many of these species have reversible features in their CVs at E = ca —0.07 V versus Ag/AgCl/MeOH and can undergo a photoreduction in the solid state which can be reversed by dissolution [110]. 

Information on the solid-state structures of cyclosilaphosphanes is lacking and there have been limited studies of their chemical behaviour. As might be expected, these ring systems may act as P-mono, -di- or -tridentate ligands towards transition metal centres, as illustrated by the examples given in Figure 10.10. ... 

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