Metal Complexes of Alkyne-Bridged α-Amino Acids

Abstract

The palladium‐mediated coupling of p‐ethynylphenylalanine (p‐epa) with different halogenated benzenes yielded alkyne‐bridged α‐amino acids. A series of cationic mono‐ to hexanuclear (Ph3P)2Pt complexes with the anions of p‐ethynylphenylalanine and alkynyl‐ or benzene‐bridged di‐, tri‐, tetra‐ and hexa‐ethynyl phenylalanines as N,O‐chelate ligands was prepared. N‐t‐Boc‐p‐ethynylphenylalanine methyl ester was metal‐substituted to give complexes of the types Ph3PAu‐C≡C–R and (Et3P)2Pt(C≡CR)2. The benzene‐bridged di‐, tri‐, tetra‐ and hexa‐p‐ethynylphenylalanine methyl esters form Schiff bases with ferrocene aldehyde and a tripodal ligand was obtained from Ph2PCH2CH2CH2NH2 and the benzene‐bridged tri‐ethynylphenylalanine. The structure of (Ph3P)2Pt[NH2C(H)(CH2C6H4C≡CH)CO2]+ BF4− was determined by X‐ray diffraction.

Star-Shaped Conjugated Systems

“…The carboranes are the wheels at the rigid scaffold to form nanocars which are proposed to show defined motions at smooth surfaces. Tripodal small stars with peripheral amino acids have been synthesized and their complexation with metals has been investigated [130,131]. Such supramolecular interacting molecules with defined structure may be of interest in pharmacology or as chiral catalyst.…”

“…Methylsulfanyl and methylsulfanylethynyl capped derivatives have been also employed to mediate the self-assembly of gold nanoparticles [186]. The scaffold was substituted by amino acid derivatives in order to generate new ligands and pharmaceutical active compounds [130,131]. Although the tetra arm substituted core is reminiscent of a disc only three compounds with liquid crystalline behavior has been published (Figure 21) [187,188].…”

“…For example, they were employed to design new ligands for multimetal complexes [131,230,231,232,233,234]. Especially the cobalt complexes, were subsequently used to prepare carbon nanomaterials by pyrolysis [235].…”

STRUCTURAL ASPECT OF PLATINUM COORDINATION COMPOUNDS: PART III. MONOMERIC SQUARE PLANAR (Pt A2XY AND PtABXY) AND TRIGONAL BIPYRAMIDAL PtII COORDINATION COMPOUNDS

“…Ten of them are cis with Υ = Ο [362][363][364][365][366][367][368][369][370]. In eight of these [362][363][364][365][366][367][368][369] there is a hetero-bidentate (0,N) divalent anionic ligand with two PPh 3 molecules. In seven of these [362][363][364][365][366][367][368] the chelate forms a five-membered metallocycle with O-Pt-N angles ranging from 77.6(2)° to 81.0(3)° (79.3° average).…”

“…In eight of these [362][363][364][365][366][367][368][369] there is a hetero-bidentate (0,N) divalent anionic ligand with two PPh 3 molecules. In seven of these [362][363][364][365][366][367][368] the chelate forms a five-membered metallocycle with O-Pt-N angles ranging from 77.6(2)° to 81.0(3)° (79.3° average). In the other case [368] there is a six-membered metallocycle with angles of 87.7(6)° and 86.5(5)°, respectively, for the two crystallographically independent molecules.…”