Lanthanide(III)-bis(cyclopropylethinylamidinates): Synthesis, structure, and catalytic activity

New Lanthanide Alkynylamidinates and Diiminophosphinates

“…The bond lengths P1-N1 (1.593(2) Å), P1-N2 (1.594(2) Å), P2-N3 (1.597(2) Å) and P2-N3 (1.593(2) Å) are almost equal, confirming the delocalization of the negative charge in the N1-P1-N2 and N3-P2-N4 units, respectively. The bond angles N1-Ce-N2 (60.96(7)°) and N3-Ce-N4 (60.80(7)°) in 9 are somewhat larger than those observed in [{c-C3H5-C≡C-C(NR)2}2 Ce(µ-Cl)(THF)]2 (R = i Pr, Cy) [45]. The bond angles Ce-Cl1-Li, Cl1-Li-Cl2, and Cl1-Ce-Cl2 are 39.80(10)°, 97.7(2)° and 79.01(3)°, respectively, to form the rhomb-shaped Ce-Cl1-Li-Cl2 unit.…”

“…The molecular structure of 8 is depicted in Figure 4; the crystal and structural refinement data are summarized in Table 1 ion still leaves room for an additional THF ligand, resulting in a formal coordination number of seven around neodymium. It has been pointed out earlier [45], that in this respect the cyclopropylethynylamidinates differ from the related dimeric yttrium, ytterbium, and lutetium bis(guanidinato) complexes such as [{(Me3Si)2NC(N i Pr)2}2Y(µ-Cl)]2 [60] and [{(Me3Si)2NC(NCy)2}2Ln(µ-H)]2 [61]. In these compounds, the higher steric demand of the supporting guanidinate ligands prevents the formation of THF adducts, resulting in six-coordinate lanthanide ions.…”

“…The phenomenon of "ate" complex formation via retention of alkali metal halides in the products is quite common in organolanthanide chemistry [68]. It can be traced back to the strong tendency of the large Ln Pr, Cy) [45]. Likewise, the Ce-Cl distance (average 2.810 Å) is very similar.…”

“…All glassware was oven-dried at 120 °C for at least 24 h, assembled while hot, and cooled under high vacuum prior to use. The starting materials, anhydrous LnCl3 (Ln = Ce, Nd) [76] and Li[Ph2P(NSiMe3)2] [66,67], and compound 8 [45] were prepared according to the literature methods. n BuLi, phenylacetylene, and N,N′-dicyclohexylcarbodiimide were purchased from Aldrich and used as received.…”

“…In subsequent contributions, we described the first trivalent rare-earth metal complexes comprising the new cyclopropylethynylamidinate ligands and their use as guanylation, hydroamination, and hydroacetylenation catalysts [45][46][47].…”