Amines, coordinated

Like mthenium, amines coordinated to osmium in higher oxidation states such as Os(IV) ate readily deprotonated, as in [Os(en) (NHCH2CH2NH2)] [111614-75-6], This complex is subject to oxidative dehydrogenation to form an imine complex (105). An unusual Os(IV) hydride, [OsH2(en)2] [57345-94-5] has been isolated and characterized. The complexes of aromatic heterocycHc amines such as pyridine, bipytidine, phenanthroline, and terpyridine ate similar to those of mthenium. Examples include [Os(bipy )3 [23648-06-8], [Os(bipy)2acac] [47691-08-7],... 

Thermoplastic resins, self-reinforced, 26 Thermoplastics, preparation of, 257-258 Thermoplastic step-growth polymers, 3 Thermosetting polyester resins, 29-31 Thermosetting resins, 3-4, 19 Thermotropic compounds, 49 THF. See Tetrahydrofuran (THF) Thiobisphenol S (TBPS), 364 Thionyl chloride, 80 activation of, 111 3,3 -linked polymers, 480 Tin-amine coordination complex, 234 Tin compounds, 86, 232-233... 

Reedijk J, Fichtinger-Schepman AMJ, Oosterom AT van, Putte P van de (1987) Platinum Amine Coordination Compounds as Anti-Tumour Drugs. Molecular Aspects of the Mechanism of Action. 67 53-89 Rein M, see Schultz H (1991) 74 41-146... 

TaniaPhos with (9) or (5) Reacting TaniaPhos with (9) in THF at r.t. resulted in amine coordination (Scheme 23.6) ... 

Reedijk, J., Fichtinger-Schepman, A.M.J., van Oosterom, A.T., and van de Putte, P. (1987) Platinum amine coordination compounds as anti-tumor drugs. Molecular aspects of the mechanism of action. Struct. Bonding (Berlin) 68, 53-72. 

Studies of the transfer of Br+ and I+ from amine-coordinated halonium ions to acceptor l-co-alkenols have been undertaken to determine the mechanism in an effort to assist in the development of chiral transfer reagents. Transfer of Br+ and I+ from two commercially available dimeric hydroquinine and hydroquinidine ligands ((DHQ)2PHAL and (DHQD)2PHAL) to various 1, (o-alkenols and l,co-alkenoic acids is shown to provide enantiomeric excesses of 4-47% depending on the acceptor alkene. 

Dendrimers with Multiple Amine Coordinating Units... 

The fact that complex 38 does not react further - that is, it does not oxidatively add the N—H bond - is due to the comparatively low electron density present on the Ir center. However, in the presence of more electron-rich phosphines an adduct similar to 38 may be observed in situ by NMR (see Section 6.5.3 see also below), but then readily activates N—H or C—H bonds. Amine coordination to an electron-rich Ir(I) center further augments its electron density and thus its propensity to oxidative addition reactions. Not only accessible N—H bonds are therefore readily activated but also C—H bonds [32] (cf. cyclo-metallations in Equation 6.14 and Scheme 6.10 below). This latter activation is a possible side reaction and mode of catalyst deactivation in OHA reactions that follow the CMM mechanism. Phosphine-free cationic Ir(I)-amine complexes were also shown to be quite reactive towards C—H bonds [30aj. The stable Ir-ammonia complex 39, which was isolated and structurally characterized by Hartwig and coworkers (Figure 6.7) [33], is accessible either by thermally induced reductive elimination of the corresponding Ir(III)-amido-hydrido precursor or by an acid-base reaction between the 14-electron Ir(I) intermediate 53 and ammonia (see Scheme 6.9). 

In closely related experiments it was shown that sp C—H activation takes place reversibly within the coordinahon sphere of the electron-rich Ir(I)-diphosphine complex 58 (Scheme 6.9) to form an alkyl-amino-hydrido derivative 57 reminiscent of the CCM intermediate 24 the solid-state structure of 57 is shown in Figure 6.13 [40]. It appears that C—H activation only takes place after coordination of the amine function to the Ir(I) center (complex 58, NMR characterized). Amine coordination allows to break the chloro bridge of 59 and to augment the electron density of the metal center, thus favoring oxidative addihon of the C—H bond. Most importantly, the microscopic reverse of this C—H activation process (i.e. C—H reductive elimination) models the final step of the CCM cycle (see Scheme 6.1) indeed, the reaction of Scheme 6.10 is cleanly reversible at 373 K. 

It has been proposed that Ru plays an important role in the oxidation of amines coordinated to ruthenium. A ruthenium(IV) amido species, [Ru(sar-H)] ", characterized by UV-vis spectroscopy, has been generated by two-electron oxidation of [Ru(sar)] " " (sar = 3,6,10,13,16,19-hexa-azabicyclo[6.6.6]eicosane)." This species is short lived and is rapidly transformed into a Ru(II) imine species. 

Although oxazolines can be used as auxiliaries and later removed they have also been retained in target molecules which have then been used as ligands for a variety of asymmetric transformations. Ferrocenes carrying oxazoline and phosphine coordination sites ° ° " , oxazoline and amine coordination sites, and ferrocene bis-oxazoli-nes have been synthesized by the method of Scheme 141. 

The peroxy complex of titanium(IV), Ti(02)(edta)2, has been used as part of an analytical method for either titanium(IV) or H202. More recently the structural nature of TiO(edta)2- in solution and the reaction of TiO(edta)2- with H202 to form Ti(02)(edta)2 have been investigated over the pH range 2.0-5.2. Two distinctly different primary coordination spheres in terms of spectral properties and reactivities towards H202 are observed for TiO(edta)2" solutions in this pH range. As shown in Scheme 2, these are the aquated forms (A), TiO(edtaH )(H20), 2, having two coordinated carboxylates and two amines and one coordinated water, and the fully chelated forms (B), TiO(edtaH ) 2, with three carboxylates and two amines coordinated to titanium(IV).115... 

Under mild conditions, hydroformylation of olefins with rhodium carbonyl complexes selectively produces aldehydes. A one-step synthesis of oxo alcohols is possible using monomeric or polymeric amines, such as dimethylbenzylamine or anion exchange resin analog to hydrogenate the aldehyde. The rate of aldehyde hydrogenation passes through a maximum as amine basicity and concentration increase. IR data of the reaction reveal that anionic rhodium carbonyl clusters, normally absent, are formed on addition of amine. Aldehyde hydrogenation is attributed to enhanced hydridic character of a Rh-H intermediate via amine coordination to rhodium. 

Fig. 7.6. The stereoselective template reaction of formaldehyde and nitromethane with primary amines coordinated in a cis-arrangement.

Platinum Amine Coordination Compounds as Anti-Tumor Drugs. Molecular Aspects of the Mechanism of Action... 

Synthesis and Structure of Platinum Amine Coordination Compounds. 57... 

Platinum Amine Coordination Compounds as Anti-Tumor Drugs... 

Fig. 1. Examples of Pt(II) and Pt(IV) amine coordination compounds most of these are playing a role in clinical or mechanistic investigations...

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