Tetrahedral metal clusters

Pump-probe measurements of optical limiting have been carried out on very few organometallic complexes results from these studies thus far are restricted to a range of tetrahedral metal clusters. 

In the complex [Cu(L)4]PF6 (L = 3-cyano-6-methylpyrid-2(lH)-one), the hydrogen-bonded linkage involves the amido R2(8) supramolecular synthon [Fig. 20.4.15(a)]. Each Cu(I) center serves as a tetrahedral node in a fourfold interpenetrated cationic diamondoid network. The tetrahedral metal cluster [Mn(/z3-OH)(CO)3]4 can be used to construct a diamondoid network with the linear 4,4/-bipyridine spacers [Fig. 20.4.15(b)],... 

Answer. A tetrahedral metal cluster is expected to exhibit a eve of 60 (sep of six) whereas if viewed as a tetracapped tetrahedron the sep remains six but the eve is 68 (tetra-M-capped M4 tetrahedron is 60 + 4 x 12 = 108 from which we subtract 4x10 electrons in the change from four M to four E). A M8 cube should have a... 

Figure 17. Schematic interaction diagram for a tetracapped tetrahedral metal cluster. (reproduced with permission from Professor M. B. Hall) The orbital energy ordering in the center column is based on the result of ab initio HF calculations on the Tj MojCn cluster.

Ting-Wah Chu C, Yip-Kwai Lo F, Dahl LF (1982) Synthesis and stereochemical analysis of the [Fe4(NO)4 (.Mu.3-S)4]N Series (N=0, —1) which possesses a Cubanelike Fe4S4 core direct evidence for the antibonding tetrametal character of the unpaired electron upon a one-electron reduction of a completely bonding tetrahedral metal cluster. J Am Chem Soc 104 3409-3422... 

Some Exeumples of Tetrahedral Metal Cluster Compo ands... 

Among tetrahedral metal clusters the carbonyl complexes are the more representative. Neutral carbonyl clusters of cobalt and rhodium have similar structures (Fig. 2.16) with nine terminal and three edge-bridging carbonyl... 

Figure 1.11 The formation of metal clusters during the nucleation of a new phase. The co-ordination is first tetrahedral, leading to 5-fold symmetry, until the 13-atom icosahedron is formed which transforms into the cubic icosahedron of the stable phase...

Exploratory solid state synthesis seems to be the only workable route to new phases because of a general inability to predict relative phase stabilities and thence structures or compositions , published in K4La6li40s A new Structure Type for Rare-Earth-Metal Cluster Compounds that Contain Discrete Tetrahedral K4l Units. S. Uma, J.D. Corbett, Inorg. Chem. 1999, 38, 3831-3835. 

The cluster anion, [Os3Ir(CO)i3], was prepared in 50% yield by reaction of Os3(CO)i2 with [Ir(CO)4]. The single-crystal X-ray structure analysis shows it to consist of a tetrahedral metal core with one of the 13 carbonyl ligands bridging. The catalytic activity for carbonylation of... 

The tetrahedral Al incorporated in mesoporous silica reduces considerably the quantity of amorphous carbon, increasing the MWCNTs selectivity, due to the formation of strong Bronsted acidic sites, which allow a better dispersion of iron metallic clusters. The Fe/Al-MCM41 (10) showed the best results in CNT purity and yield. This indicates that the aluminum content and its tetrahedral structural incorporation play an important role in the CNT syntheses. 

Ir4(CO)i2 reacts with the surface of MgO to generate surface species in which the tetrahedral metal framework is preserved. The structures obtained after decar-bonylation under H2 at 573 K depend on the degree of hydroxylation of the support The iridium cluster nuclearity of 4 was maintained for a low degree of MgO hydroxylation (MgO pretreated at 973 K), but it increased to 6 when the MgO was highly hydroxylated (MgO pretreated at 573 K) [206, 207]. The activity in propane hydrogenolysis of the tailored catalyst is two orders of magnitude less than that of the conventional catalyst at atmospheric pressure and 200 °C. 

The intermetallic phase [26] Na2Tl illustrates a simple application of the Zintl-Klemm concept to a group 13 metal cluster. Complete electron transfer from Na to T1 leads to the (Na" )2Tl formulation. The Tl dianion is isoelectronic with group 15 elements and thus should form similar tetrahedral structures with six two-center two-electron bonds along the edges of the tetrahedron. Indeed, the Tl anions in the Na2Tl phase form Tl4 tetrahedra, similar to the isoelectronic P4 and As4 units in white phosphorus and yellow arsenic. 

Chaur MN, Melin F, Ortiz AL et al (2009) Chemical, electrochemical, and structural properties of endohedral metallofullerenes. Angew Chem Int Ed 48 7514-7538 Stevenson S, Mackey MA, Stuart MA et al (2008) A distorted tetrahedral metal oxide cluster inside an icosahedral carbon cage, synthesis, isolation, and structural characterization of Sc4(p3-O)2 lh-Cgo. J Am Chem Soc 130 11844-11845... 

Fig. 29. The bicapped tetrahedral geometry established for the Os6(CO)18 metal cluster. For reasons of clarity the carbonyl ligands have been omitted from the illustration.

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