2011-08, Peters, Liv, Tepedino, Maria-Fatima, Haas, Thomas, Heinemann, Frank W., Wolf, Marion, Burzlaff, Nicolai

2009, Peters, Liv, Hübner, Eike, Haas, Thomas, Heinemann, Frank W., Burzlaff, Nicolai

The tripodal N,N,O ligands 3,3-bis(3,5-dimethylpyrazol-1-yl)propionic acid (Hbdmpzp) (1) and 3,3-bis(pyrazol-1-yl)propionic acid (Hbpzp) (2) form the “missing link” between the well-known bis(pyrazol-1-yl)acetic acids and related ligands with a longer “carboxylate arm”. To illustrate the reactivity of this ligand, manganese and rhenium complexes bearing the ligand bdmpzp are reported. The complexes are compared to related compounds bearing other tripod ligands such as bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) and 3,3-bis(1-methylimidazol-2-yl)propionate (bmip). Spectroscopic and structural data are used as a basis for comparison, as well as DFT calculations. Both ligands 1 and 2 and the complexes fac-[Mn(bdmpzp)(CO)₃] (3) and fac-[Re(bdmpzp)(CO)₃] (4) were characterised by X-ray crystallography.

2011-02, Haas, Thomas, Kaspar, Katrin, Forner, Konstanze, Drexler, Matthias, Fischer, Helmut

2005, Drexler, Matthias, Haas, Thomas, Yu, Sze-Man, Beckmann, Henning, Weibert, Bernhard, Fischer, Helmut

Pentacarbonyl dimethylamino(methoxy)allenylidene tungsten, [(CO)5Wdouble bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashC(OMe)NMe2] (1b), reacts with one equivalent of primary amines, H2NR, by selectively replacing the methoxy group to give dimethylamino(amino)allenylidene complexes, [(CO)5Wdouble bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashC(NHR)NMe2]. When the amine is used in excess both terminal groups, OMe as well as NMe2, are replaced by the primary amino group giving [(CO)5Wdouble bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashC(NHR)2 ]. The NHR substituent in these complexes may be modified by deprotonation with LDA followed by alkylation. The replacement of the methoxy group in 1b by a secondary amino group, NR2, can be achieved by a stepwise process. Addition of Li[NR2] to the Cγ atom of 1b affords an alkynyl tungstate. Subsequent OMe− elimination induced by TMS-Cl/SiO2 yields the allenylidene complexes [(CO)5Wdouble bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashC(NR2)NMe2]. When bidentate diamines are used instead of monoamines both substituents, OMe and NMe2, are replaced and allenylidene complexes are formed in which Cγ constitutes part of a 5-, 6-, or 7-membered heterocycle. The reaction of [(CO)5Crdouble bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashC(OMe)NMe2] (1a) with diethylene triamine affords an allenylidene complex with a heterocyclic endgroup carrying a dangling CH2CH2NH2 substituent. All reactions follow a strict regioselective attack of the nucleophile at Cγ and proceed with good to excellent yields. The addition of N–H to the Cαdouble bond; length as m-dashCβ bond is not observed. By applying either one of these routes nearly any substitution pattern in bis(amino)allenylidene complex can be realized.

2009, Peters, Liv, Tepedino, Maria-Fatima, Haas, Thomas, Hübner, Eike, Zenneck, Ulrich, Burzlaff, Nicolai