A new, interdisciplinary research area has emerged known as bioorganometallic chemistry. It focuses on the introduction of organometallic fragments into biomolecules (see, for example, structure on the right). "Classical" α-amino acid and peptide ligands have proven particularly versatile, and provide access to compounds that display interesting stereochemistry. α-Amino acids and peptides can be synthesized, labeled, stabilized, or activated by organometallic fragments.

o-Formylaryl)palladium complexes [Pd{C 6 H(CHO)-6-R 3 -2,3,4}X(N-N)] [R ) OMe; X ) Cl; N-N ) bpy (2,2′-bipyridine) (1a), tmeda (N,N,N′,N′-tetramethylethylenediamine) (1b). R ) H; X ) Br; N-N ) bpy (2a), tmeda (2b)] react with ylides PhCHdPPh 3 , pyCHdPPh 3 (py ) 2-pyridyl), or ClCHdPPh 3 to give the (o-alkenylaryl)palladium derivatives [Pd{C 6 -The compounds 3a, 4, and 6a,b are obtained as mixtures of E and Z isomers, whereas the formation of 3b and 5 is stereoselective (E isomer). The reaction of the (o-acetylaryl)palladium complexes [Pd{C 6 HC(O)Me-6-(OMe) 3 -2,3,4}Cl(tmeda)] ( 7) and [Pd{C 6 H 4 (C(O)Me)-2}Br(bpy)] (8) with bases results in the formation of the 3-palladaindan-1-ones [Pd(κ 2 -{C 6 HC(O)CH 2 -6-(OMe) 3 -2,3,4})(tmeda)] (9) and [Pd(κ 2 -{C 6 H 4 C(O)CH 2 -2}(bpy)] (10). Complexes 3b and 6a,b react with alkynes RCtCR′ to give indenylpalladium complexes [Pd{η-C 9 HBn-1-R-2-R′-3-(OMe) 3 -5,6,7}(tmeda)]TfO [Bn ) benzyl, TfO ) CF 3 SO 3 , R ) R′ ) Me (11); R ) C(O)Me, R′ ) H (12)] and [Pd{η-C 9 H 4 Bn-1-R-2-R′-3}(N-N)]TfO [R ) R′ ) H, N-N ) bpy (13a), tmeda (13b); R ) R′ ) Me, N-N ) bpy (14a), tmeda (14b); R ) R′ ) Et, N-N ) bpy (15a), tmeda (15b); R ) R′ ) Ph, N-N ) bpy (16a), tmeda (16b); R ) Ph, R′ ) H and R ) H, R′ ) Ph, N-N ) bpy (17a); R ) H, R′ ) Ph, N-N ) tmeda (17b); R ) Ph, R′ ) Me, N-N ) bpy (18a), N-N ) tmeda (18b)]. Complex 3b reacts with Me 2 CdCdCH 2 , CS 2 , or MeNdCdS to give [Pd(η 3 -CMe 2 C{C 6 H(E-CHdCHPh)-6-(OMe) 3 -2,3,4}CH 2 )(tmeda)]Tf O (19), [Pd(S 2 C{C 6 H-(E-CHdCHPh)-6-(OMe) 3 -2,3,4})(tmeda)]TfO (20), or [Pd(SC(NMe){C 6 H(E-CHdCHPh)-6-(OMe) 3 -2,3,4})(tmeda)]TfO (21). The crystal structures of 12, 17b, and 18a have been determined; the hapticities of the indenyl five-membered rings are intermediate betwen η 3 and η 5 .

The reactions of [Pd(E-R)Cl(tmeda)] [R = C6H(E-CHCHPh)-6-(OMe)3-2,3,4; tmeda = N,N,N‘,N‘-tetramethylethylenediamine] with Tl(CF3SO3) and CH⋮CH, PhC⋮CPh, or PhC⋮CH selectively give compounds [Pd(η-Ind)(tmeda)]CF3SO3 [Ind = 1-benzyl-5,6,7-trimethoxyindenyl (2), 1-benzyl-2,3-diphenyl-5,6,7-trimethoxyindenyl (3), 1-benzyl-3-phenyl-5,6,7-trimethoxyindenyl (4)]. When a mixture of [Pd(E-R)Cl(bipy)] (bipy = 2,2‘-bipyridine) and [Pd(Z-R)Cl(bipy)] is reacted with Tl(CF3SO3) and MeC⋮CMe, the complex [Pd(η-Ind)(bipy)]CF3SO3 [1-benzyl-2,3-dimethyl-5,6,7-trimethoxyindenyl (5)] is obtained. The structures of 3 and 4 have been determined by X-ray studies at 203 and 173 K, respectively. According to the structural data for 3 and 4, the hapticity of the indenyl ligands is intermediate between η3- and η5-coordination.

Ein neues interdisziplinäres Forschungsgebiet ist die Biometallorganische Chemie; sie befaßt sich mit der Einführung von metallorganischen Fragmenten in Biomoleküle (siehe z. B. Struktur rechts). Die „klassischen”︁ α‐Aminosäure‐ und Peptidliganden haben sich dabei als besonders vielseitig erwiesen und eröffnen unter anderem einen Zugang zu stereochemisch interessanten Verbindungen. α‐Aminosäuren und Peptide können durch metallorganische Verbindungen synthetisiert, markiert, stabilisiert oder aktiviert werden.

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