Triple-decked complexes

The reaction of 2- and 3-borolenes C4H6BR (R = Ph, Me, C H, OMe) with Co, Fe and Mn carbonyls leads, under dehydrogenation of the borolenes, to i7 -borole complexes. 2-Borolene and 3-borolene also react with Mn2(CO), at 160°C to a red-brown triple-decked complex ... 

A dehydrogenating complexation of the 2- and 3-borolenes C4H5BR (R = Me, Ph) also occurs with [Rh(7j -C2H4)2C1]2, forming a triple-decked complex ... 

The (Et2C2B2Me2S)2Co2(CO)4 complex is formed if the dihydrothiadiborole is treated with Co2(CO)g in toluene as an isolable intermediate -, leading to the triple-decked complex ... 

Dihydro-l,3-diborolenes are accessible as pentaorgano derivatives " and serve as ideal precursors of the diborolyl radieal. The formation of the radical and its interaction with a metal center is formally described as a metal oxidation. The resulting 2,3-dihydro-1,3-diborolyI ligand is either a three-electron donor or an anionic four-electron donor. l,3,4,5-Tetraethyl-2-methyl-2,3-dihydro-l,3-diborole reacts with [T -CpNi(CO)2] or (T7 -Cp>2Ni in hot mesitylene to yield a sandwich complex and a triple-decked complex ... 

The dark red 30-electron triple-decked complex (CgH 2)Rh-/u.-[C4H4B2-(NMe2)2]Rh(CjjH 2) can be made from [(l,5-CjjH,2)RhCl]2. 1,4-Diborabenzene acts... 

Reaction of the Zn complex itself with CoClj yields different compounds by ligand transfer , e.g., T7 -CpCo(Et2C2B2Me2S) (83%), (ij -Cp)2Fe (70%) and traces of the triple-decked complex Tj -CpFe- A-(Et2C2B2Me2S)FeCp-i7. ... 

The first triple-deck complexes that contain a bridging boratabenzene have been prepared through treatment of Cp Ru(C5H5B-Me) withmetallo-electrophiles (Scheme 17).32 The structure of the illustrated adduct has been established by X-ray crystallography. 

In the system [Fe(CO)2Cp]2/55 the main products are FeCp2, the borabenzene derivative 56, and two triple-decked complexes CpFe[/x-(2-EtC4H3BPh)]FeCp and CpFe[/u,-(2-ViC4H3BPh)]FeCp with a central borole ligand (52). 

The triple-decked Tj -CpFe(PhBC4H3Et)FeCp-T7 complex is formed from 1-phenyl-4,5-dihydroborepine and [T) -CpFe(CO)2l2 by thermal reaction the boraben-zene derivative 77 -CpFe(PhBC5H4Me) also forms. With Mn2(CO), l-phenyl-4,5-dihydroborepine yields the triple-decker complex (CO)3Mn(PhBC4H3Et)Mn(CO)3. The borole complexes described so far are available using stable boroles as reactants. But borole molecules can also be generated from precursers in the course of complexation. 

Dihydro-l,2,5-thiadiboroles (Et2C2B2R2S) have remarkable acceptor properties toward metal-ligand moieties. Dihydrothiadiborole-derived complexes can be achieved thermally or photochemically, e.g., Co and Fe sandwich, triple-decked and even tetradecked complexes are known, all having direct metal-boron bonds. 

A similar mixed complex with Mn and Co is obtained by reacting the triple-decked cobalt compound XVII with hlnjCCO), ... 

The existence of complex anions, e.g., [(CO)3Mn(Et2C2B2Me2S)] or [(Et2C2B2Mc2S)2Co], allows the preparation of triple-decked and tetradecked... 

Reaction with transition metal halides to give triple-decked and tetra-decked complexes 6.5.3.4 C H, B2Fe03S... 

Of the pentaphospholide ion only ) -coordination is known, sometimes with additional g -coordination. A characteristic feature is the formation of triple-decker complexes with P5 as the middle deck <94CCR1>. Their electronic structure has been explored <89JA2030>. 

The distortion is even more severe in the triple-decker complex (CpMo)2As4S where the planar middle deck is closer to an allylic Ass group and a separate AsS group rather than an AS4S ring <90IC798>. 

Since the first preparation of triple-decker complexes, the possibility of constructing oligo-decker and poly-decker species [quadruple-decker (95), multiple-decked stacked compounds (55)] has received attention. At this time, few published data are available. 

Scheme 6.9 Preparative route to homo- and hetero-metallic triple-decker complexes 20-24 with cyclic carboranes as bridging ligands (the substituents at the boron and carbon atoms of the middle deck are alkyl groups)...

Triple-decker complexes (9 and 10, see Tripledecker Sandwich) are also accessible from CpV( - 3115)2 and 1,3-cyclohexadiene, or vanadocene and (naphthalene)Yb(THF)3, respectively. The middle-deck... 

The 1,3-doborolyl ligand (4-H) functions as a 3e donor and as a good electron acceptor (formally 3e), which allowed the formation of the first complete family of triple-decker sandwich complexes (26+-30 ) (6) ranging from FeFe+ cation (28 VE) to NiNi- anion (34 VE). In addition, the unsymmetrical triple-decker 31-34 have been reported however, we did not succeed in the synthesis of any triple-decker with CO ligands in both terminal decks. The complexes 26-34 exhibit an interesting redox behavior and reactivity. The paramagnetic triple-decker 29 and 30 react with... 

The two benzene rings in compounds like 8 lie on top of each other and thereby exhibit interesting electronic and spectroscopic interactions. Misumi [40] was successful in preparing multilayered cyclophanes with up to six benzene decks. Nowadays the mono- and bis(tricarbonylchromium) complexes 35a and 35b of the triple layered (35) as well as 36a and 36b of the quadruple layered para-cyclophane (36) are known (Fig 6c) [29],... 

Figure 5.30 MO diagram of triple-decker sandwich complexes. Orbitals that get destabilized with large-ring-middle-deck are shown in the box.

Scherer O, Schwalb J, Swarowsky H et al (1988) Triple-decker sandwich complexes with cyclo-Pg as middle deck. Chem Ber 121 443-449... 

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