Scandium group metals, complexes with

III. Complexes with Scandium, Titanium, and Vanadium Group Metals. 182... 

Single crystal X-ray structures of CpDoCp HScCl and CpDoCp HScMe were published. Both molecules showed a similar structure. The Cl complex is one of the very few examples of a di(cyclopentadienyl)scandium chloride without bridging chlorine atoms. This terminal Sc-Cl distance is 2.4574(12) A shorter than in a scandium chloride complex with bridging chlorine atoms like [Cp"2Sc(/r-Cl)]2 with 2.58 A. The scandium metal atom is surrounded by four ligands in a distorted tetrahedral geometry. The coordinated dimethylamino group decreases the Lewis acidity... 

In this article the term organometallic compound includes alkyl and aryl derivatives of the rare earths—the transition metals of group III, scandium, yttrium, lanthanum and the lanthanides cerium to liitetium with covalent metal-to-carbon a-bonds, as well as the so-called 77-complexes with more than monohapto metal-to-carbon bonds, for example cyclopentadienyl and olefin complexes, metal acetylides, but not carbonyls, cyanides and isocyanide complexes. Derivatives of scandium, yttrium and lanthanum are included and discussed together with the compounds of the lanthanides, because of many similarities in the synthesis and the chemistry of these organometallic derivatives of the rare earths. 

Transition metal p-diketiminate complexes are typically prepared by one of three routes. In one, these complexes are prepared by the reaction of a metal halide with an alkali metal P-diketiminate generated from the reaction of the p-diketiminate with an alkali metal base. An example of this synthesis is shown for the scandium system in Equation 4.51 In a second method, these complexes are prepared by the reaction of a transition metal complex containing a basic ligand, such as an alkyl or amido group, with the neutral p-diketimine. Two examples of this route for zirconium systems are shown in Equations 4.52 and 4.53, 3... 

Scandium group elements as well as the lanthanides form allyl complexes in which the central atom has H- 3 oxidation state, while the actinides give compounds possessing + 4 oxidation states (Table 7.14). These complexes are formed by reactions of metal halides with allyl compounds of magnesium, lithium, tin, etc. " " ... 

This chapter is devoted to the most significant developments of early-transition metal compounds ligated by N-heterocyclic carbene ligands (from group 3 to group 7 scandium to rhenium) [10]. When appropriate and available, the structural features of these metal complexes will be discussed. The synthetic pathways, bonding nature of the Ccarbene-M> reactivity, and applications of such derivatives (with a special emphasis on their use in catalysis) will be discussed [11]. 

In a systematic study, it was demonstrated that, using a specially designed bulky benzamidinate ligand, it is possible to isolate mono(amidinato) dialkyl complexes over the full size range of the Group 3 and lanthanide metals, i.e., from scandium to lanthanum. The synthetic methods leading to the neutral and cationic bis(alkyls) are summarized in Scheme 56. Figure 18 displays the molecular structures of the cations obtained with Sc, Gd, and La. ... 

Cyclopentadienylamine)scandium(2,3-dimethyl-l,3-butadiene) 7 was synthesized in good yield, as shown in Scheme 2. Complex 7 reacted with benzonitrile to form a /rz-imido complex 8, the structure of which was characterized by single crystal X-ray diffraction. This product 8 was proposed to be formed by nitrile insertion followed by an attack of another diene methylene group on the carbon atom of the imido intermediate.3 An unsaturated metal imido species was formed, which easily dimerized to produce 8. However, the yield of 8 was not reported. 

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