Binuclear rhenium complex

Binuclear complexes of naphthalene (VIII) and of benzene (IX) with [Os(NH3)5]2+ and [Ru(NH3)5]2+ moieties were reported by Taube et al. (19), in which anti- //-1,2-rj2 3,4- 2) coordination of the arene is present. This bonding mode was first observed by Pasman et al. (20) in the binuclear Rhenium complex X. Wolczanski et al. (21) obtained complex XI from the mononuclear complex [Ta(0—Si Bu3)3 2-(N,C)-pyridine ] and benzene. Each tantalum atom is bound unsymmetrically to one C=C bond of benzene with a weak interaction to a third carbon atom the bonding may be described as a distorted tj3-enyl. In the dinuclear cobalt complex XII, the xylene functions as a bis(enyl)-ligand (12,22). 

Infrared Spectroelectrochemical Analysis of the Binuclear Rhenium Complex of the Form, [Re(CO)3Cl]2(tpbq)... 

Other than (CO)4Fe(CHO) and derivatives thereof (22-25), only a few of the formyl complexes in Table I show significant stability at room temperature. Of these, the binuclear rhenium formyl cis-(CO)5ReRe(CO)4(CHO) [19, Eq. (5)] has received the greatest attention (37. 38. 42. 47). The manganese and mixed manganese/rhenium homologs (12, 18) can be similarly prepared, but are less stable (35. 38, 47). 

Although the structure of the CO2 adduct, which is an important intermediate in the photocatalysis of the rhenium complexes, has not yet been confirmed, several proposals have been made. As candidates, a C02-bridged binuclear complex (CO)3(dmb)Re—CO2—Re(dmb)(CO)3 (16, dmb = 4,4 -dimethyl-2,2 -bipyridine) and a rhenium carboxylate complex Re(bpy) (COlsCCOOH) (17) were synthesized. 

Binuclear carbonyl complexes with M—M bond analogous to Mn2(CO)io have been prepared for technetium and rhenium. The rhenium analogue has been synthesized by the carbon monoxide reduction of Rc207 or KRe04 (eq (5)) [3] or by reduction of anhydrous Re(III) or Re(V) chloride by sodium under CO pressure (eq (6)). [15]. The physical and structural properties of Tc2(CO),o and Re2(CO)io are listed in Table 9.1. 

Earlier, Herrmann et al. (1976 a, 1976 b) found that the mononuclear (pentacar-bonyl)(hydrido)manganese complex 10.74 forms a 10 1 mixture of the di- and trinuclear complexes 10.75 and 10.76 with diazomethane, if the reagents are mixed in THF at - 85 °C and the system is allowed to reach room temperature (10-34). In the same reaction with the analogous rhenium complex, only the binuclear complex... 

The binuclear rhenium(l) complex was synthesized according to the procedure by Wrighton and Morse [27] but with some modifications. Stoichiometric amounts of Re(CO)5Cl and tpbq (in 1 2 mmol ratios BL metal salt) were mixed in 50 mL benzene. The resulting mixture was stirred and heated under reflux for 5 hours at 60 C. The product was filtered under vacuum then recrystallized by dissolving in dicholoromethane and recrystallizing in n-pentane. The purified complex was filtered again under vacuum and air-dried. The brownish precipitate was obtained with a typical yield of -78%. UV-Vis (nm) 383.8 and 292.6 FTIR (cm ) 3,087.6 (broad), 999.61 - 1,092.2, 1,196.1 - 1,130.8, 717.86 - 833.65, 1,532.2 - 1,613.2, 1,474.3,... 

The binuclear rhenium(I) complex was obtained at very reasonable yield (Fig. 

Compounds of the composition [ReOCl3(N N)] have also been isolated with pyridine-2-aldi-mine and rr-acidic arylazopyridine and arylazoimidazole ligands." The products (101) are readily reduced by oxygen atom transfer reactions from Re to phosphorus atoms of phosphines which results in the formation of rhenium(III) complexes. Depending on the reaction condition and the phosphines used either mononuclear or binuclear compounds are formed." " Azo splitting reactions with arylazopyridines give access to arylimido and binuclear oxo/imido com-plexes. "" ... 

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