5/30/2023 0 Comments Main group elements![]() 1.849 Å) are at the very upper limit of a P III−C(sp 2) bond. Similar to 3 and 4, the P−C distances of the bis(acyl)phosphide substituents (av. demonstrated that heavier analogues of acac − and BAP −, [E 4 (3.053(1) Å) 30 and Bi 2Mes 4 (3.087(3) Å). However, in these compounds the bis(acyl)phosphido ligand was synthesized in the coordination sphere of the metal by acylation of a M(CO) 2(Cp*)(P(SiMe 3) 2) precursor with a preformed M−P bond. There are some few examples of complexes in which the metal is coordinated via phosphorus such as M(CO) 2(Cp*)(BAP) (M=Fe, Ru, Os). 4, 7- 9 Generally, the coordination occurs in the chelating κ 2-O,O′ mode.Ī) Keto-enol tautomerism of BAPH (R=Me, tBu, Cy, Ph, Mes) and acacH and b) reported metal complexes with BAP − ligands. 6 Analogously, several transition, main group metal, yttrium and uranium complexes incorporating the BAP − ligand have been synthesized (Scheme 1b). 3, 4 A similar situation is encountered in β-diketones, the anions of which are versatile ligands, for example acetylacetonate, acac −. 5 They exist in solution in a keto-enol equilibrium according to Scheme 1a, whereas in the solid state the enol form is favoured. ![]() 2 The first bis(acyl)phosphanes have been prepared and investigated in the 1980s by Becker and co-workers from silylphosphides and acylchlorides 3, 4 and the development of alternative synthetic routes continues to attract interest. 1 Especially, bis(acyl)phosphanes (BAPHs), (RCO) 2PH, (R=Ph, Mes), have gained much attention as precursors for the synthesis of highly reactive bis(acyl)phosphane oxide photoinitiators. Acylphosphanes and their oxides are important ligands and UV-Vis initiators for the hardening of photopolymerizable materials.
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