Transition metals trinuclear complexes

The formation of monomer and dimer of (salen)Co AIX3 complex can be confirmed by Al NMR. Monomer complex la show Al NMR chemical shift on 5=43.1 ppm line width =30.2 Hz and dimer complex lb 5=37.7 ppm line width =12.7 Hz. Further instrumental evidence may be viewed by UV-Vis spectrophotometer. The new synthesized complex showed absorption band at 370 nm. The characteristic absorption band of the precatalyst Co(salen) at 420 nm disappeared (Figure 1). It has long been known that oxygen atoms of the metal complexes of the SchifT bases are able to coordinate to the transition and group 13 metals to form bi- and trinuclear complex [9]. On these proofs the possible structure is shown in Scheme 1. 

All these results indicate that one is just at the beginning of understanding the function of catalysts being deposited on a semiconductor. There is still quite a confusion in many papers published in this field. Therefore the catalytic properties depend so much on the procedure of deposition . It seems to be rather difficult to produce a catalyst for 02-formation, as shown by results obtained with Ti02 (see e.g.) . Rather recently new concepts for the synthesis of new catalysts have been developed applicable for multielectron transfer reactions. Examples are transition metal cluster compounds such as M04 2RU1 gSeg and di- and trinuclear Ru-complexes . 

Dinuclear Pt complexes of the type [ Pt(PR3) 2(p-S)2] are also known to serve as the good precursors to the trinuclear clusters. A series of triangular cluster cores M Pt2(p3-S)2 has been constructed therefrom (M = transition metals, main-group metals).50... 

The presence of multiple donor sites enables cyclophosphines cyclo-(PR) n = 3-6) to function as versatile two-electron ligands in mono- di- or trinuclear metal complexes as discussed in Section 7.1.1 (see structures 7.1-7.3) in some case the reaction of cyclo-(PR)5 with transition metal complexes results in P-P bond activation, which may occur either with retention or fragmentation of the oligophosphine (for examples, see structures 7.4-7.5). ... 

The rapid development of the chemistry of transition metal complexes containing terminal carbene (A) or carbyne (B) ligands (7) has been followed more recently by much research centered on bridged methylene compounds (C) (2). The importance of /t-methylidyne complexes, whether in recently established binuclear examples (D), the well-known trinuclear derivatives (E), or the unusual complexes (F), has also become apparent. All are based on one-carbon (C,) fragments, and considerable interest is centered on their possible significance as models for intermediates in surface-catalyzed reactions between carbon monoxide and hydrogen (Fischer -Tropsch reactions) and related processes. These topics have been extensively ... 

Several groups have been investigating the use of transition metal complexes for the catalytic conversion of hydrosilanes to silyl formates [Eq. (50)]. The anionic trinuclear cluster [HRu3(CO)M]-1 has been effective for... 

A (triphenylene)Cr(CO)3 complex and its crystal structure212 has been described in which the Cr—C distance of this -complex is around 2.2 A, common for transition-metal-carbon bond distances. A redox-tunable near-IR dye based on a trinuclear ruthenium-(II) complex of hexahydroxytriphenylene 87 has been prepared.220 Here, the absorption maximum of the... 

Replacement of the Au(PR3)C1 molecule by the AuC12 anion in reactions with transition metal anions gives rise to linear trinuclear Au-M-Au heterometallic complexes, as in the reactions (234)... 

Scheme 8.15 Stone s synthetic route to obtain dinuclear and trinuclear transition metal complexes such as 58 (with M (L) — Pt(PR3)2, (C5Me5)Rh(CO), (CgMe6)Cr(CO)2, Fe(CO)4, etc.) and 59 using the isolobal analogy (a R = H, b R = Me R = p-Tol)...

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