Bridged compounds complex

Cp(PMe3)2RuC=CH and the corresponding vinyl compound react with 1 to give the expected hydrozirconated complexes [225, 226]. Hydrozirconation reactions were also observed with the vinyl and acetylenic ferrocenyl complexes [227]. In marked contrast, the iron complex Cp (dppe)Fe-C=CH reacts anomalously with Schwartz s reagent to form acetylide Cj-bridged heterodinuclear complexes (Scheme 8-31) [228]. 

It appears that a modified mechanism operates when tr .s-(o-tolyl)phosphine is used as the ligand,133 and this phosphine has been found to form a palladacycle. Much more stable than noncyclic Pd(0) complexes, this compound is also more reactive toward oxidative addition. As with the other mechanisms, various halide adducts or halide-bridged compounds may enter into the overall mechanism. 

Probably the first metal alkene complex was Zeise s salt, K[Pt(C2H4)Cl3] or the bridged compound [PtCl2(C2H4)]2. These compounds were first prepared by Zeise in about 1825. The palladium analogs of these compounds are also now known. A large number of metal alkene complexes are known, and some of the chemistry of these materials will be described here. 

The advantage of these complexes is that each Pt complex is isolated in pure form, and the crystal structure is known. Based on 1H-and 195Pt-NMR spectroscopy, the antitumor active compounds were found to be disrupted as shown in Fig. 20, giving finally [Pt(NH3)2(H20)2]2+, which is the same hydrolysis product as ds-DDP and is responsible for the activity. Therefore, the subsequent reaction with DNA bases and the mechanism would be the same with those of cis-DDP. The antitumor inactive compounds are relatively stable and are disrupted only to dinuclear amidate-bridged compounds. No further decomposition to [Pt(NH3)2(H20)2]2+ occurs. 

Treatment of 77 with one equivalent of [AuCl(tht)] (tht = tetrahydrothiophene) leads to the type III AuCl bridged pincer complex 79 in high yield (counterion is Cl ) [149]. The unique complex 79 is the only heterodimetallic compound with two metal atoms attached at a carbodiphosphorane carbon(O) atom. The environment at the central carbon atom is planar in 77 and pyramidal in 78 and 79. P-C bond lengths and P-C-P angles in the dication 78 are closely related to those in the neutral Pt complex 36 (Fig. 25). The two metals of 79 attached to the carbon atom are coimected via a very short d -d ° pseudo closed shell interaction with a Pd-Au bond length of 2.8900(3) A a similar bonding situation (aurophilic attraction) is found in the gold complex 29 shown in Fig. 23. 

A new class of metalloprotelns containing polynuclear, non-heme oxo-bridged iron complexes has emerged recently. Dinuclear centers are present in hemerythrin (Hr), ribonucleotide reductase (RR), purple acid phosphatases (PAP) and, possibly, methane monooxygenase (MMO) these centers as well as model compounds are reviewed in Chapter 8. 

---