Butterfly configuration

A general summary of the chemistry of H4Os4(CO)12 is given in Scheme 10 (159, 166). Substitution reactions with phosphine, phosphites, or pyridine have been observed. An addition reaction occurs with I2 to yield the anionic species [H3Os4(CO)12I] The X-ray structure of this anion has established that the iodide is bridging between two metal centers, to yield an Os4 "butterfly configuration in which one of the metal- metal bonds of the initial Os4 tetrahedron has been broken (Os-Os = 3.817 A) (Fig. 38). Interestingly, if the two Os-1... 

The rhodium complex [Rh(acac) (C2Hi )2] reacts with the unsaturated triosmium compound to give the 60-electron cluster species [Rh0s3(y-H)2(y-acac)(CO)10J (A7) in which the acac ligand acts as a five-electron donor, one oxygen atom bridging an Os — Rh separation of 3.292(2) so that the four metal atoms adopt a butterfly configuration. 

Z = 4. The crystal structure is shown in the Figure 4.43. The La coordination polyhedron can be depicted as a folded butterfly configuration. Viewed from the two flexible -CH2-CH2- lateral units, the whole molecule can be divided into two hemispheres, one above and one below the donor atom plane. This structure effectively relaxes the repulsion among the coordination atoms and allows the central metal ion to attain its highest possible coordination number, 12. The donor atoms consist of six nitrogen atoms from one macrocyclic 24 and four nitrogen atoms from two bidentate nitrates on one side of the macrocycle and the other bidentate nitrate on the opposite site. 

Condensation of FeafCO) and [Fe(CO)3(NO)] gives [Fe4N(CO)i2] in 43% yield. The N atom bridges all four Fe atoms, which are in a butterfly configuration . 

The reaction proceeds through formation of a silirane followed by addition of a second equivalent of CS2. Based on crystallographic data, the four-membered ring adopts a butterfly configuration. This product is different from what is observed in an analogous reaction with CpfSi in which a six-membered ring is obtained in near quantitative yield... 

Figure 3 Tetrahedral and open butterfly configurations for four-atom clusters...

But Chris had an early diagnosis because of two circumstances. First, she had the typical butterfly rash on her face. The rash, with open sores in her case, is distributed in a butterfly configuration across the eyes and nose. That sign should scream lupus to any intelligent doctor. 

The butterfly configuration for a Cu4 unit (Figure 4.4, iv) has been characterized in [Cu(MDAP)]4 where MDAP = 5-methyl-2(dimethylamino)methyl phenyl, in... 

Examples of isomeric (o - a ) and (cf - cf ) compounds are known as, for example, in Equations 9.34d and 9.34e, which have planar and butterfly configurations, respectively. Compound (9.34f) is folded about the P-P linkage, whereas (9.34e) has a butterfly structure folded about a B-B linkage [14,15]. 

Fig. 11.1. Penile fracture with rupture of the Buck s fascia. The hematoma spreads to the attachment of the Colles fascia involving the penis, scrotum and perineum with typical butterfly configuration...

Another tetranuclear butterfly configuration is found in [W4(/44-C)(/r,-NMe)(/i-OCH2Bu )4(OCH2Bu )7(H)] in which the hydride is terminally bonded to one of the backbone tungsten atoms. ... 

A fourth mode of CO-coordination is also known, namely that found in the anion [Fe4(CO)i3H] " in which, as can be observed in Fig. 2.4, one carbon monoxide ligand is coordinated by the carbon atom to all four Fe-atoms which are arranged in a butterfly configuration. As also indicated in Fig. 2.4, the CO-oxygen atom appears to be also bonded to the metal polyhedron. 

Os atoms adopt a butterfly configurations. 24 Three terminal CO-groups are bonded to each metal. The acetylenic ligand lies over the butterfly. 

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