Characterization by X-ray crystallography

CH2CN)4Yb[( J.-H)2BH]2, and (CgH N)4Yb[( J.-H)2BH4]2 have been stmcturally characterized by x-ray crystallography and shown to contain ytterbium to boron hydride Yb—H—B linkages. Thermal decomposition of lanthanaboranes can be used to generate lanthanide metal borides. 

The phenyl ether oxygen atoms allow the two borazaphenanthrene rings to pivot with respect to each other, therefore this dimeric boronic acid anhydride can potentially exist in two isomeric forms, either face-to-face or helical (Fig. 18). In the face-to-face form the boron atoms of the bis(borazaphe-nanthrene) moieties have syn-orientation, while they have approximate anti-orientation in the helical form. Compound 68 has been characterized by X-ray crystallography in the helical form [109]. The dimensions of the cavity can be described by the transannular C C contacts between the carbon atoms in 2-position of the phenyl ether units, which have values of 5.12 and 6.21 A. 

The concentration of this species in liquid sulfur was estimated from the calculated Gibbs energy of formation as ca. 1% of all Ss species at the boihng point [35]. In this context it is interesting to note that the structurally related homocyclic sulfur oxide Sy=0 is known as a pure compound and has been characterized by X-ray crystallography and vibrational spectroscopy [48, 49]. Similarly, branched long chains of the type -S-S-S(=S)-S-S- must be components of the polymeric S o present in liquid sulfur at higher temperatures since the model compound H-S-S-S(=S)-S-S-H was calculated to be by only 53 kJ mol less stable at the G3X(MP2) level than the unbranched helical isomer of HySs [35]. 

The reduced alkyl complexes are reoxidized by O2 to the iron(lll) alkyls. The corresponding diamagnetic phthalocyanine iron(ll) alkyl complexes, rFe(Pc)R), were prepared by two-electron reduction of Fe(Pc) by LiAIFl4 to give [Fe(Pc) (actually the Fe(I) phthalocyanine radical anion) followed by reaction with Mel, Etl or i-PrBr. The methyl compound, [Fe(Pc)CHi] was characterized by X-ray crystallography. ... 

Rh(TPP)SnCl3, have been characterized by X-ray crystallography, and exhibit... 

Power and coworkers prepared the iron(V) bis-imide complex 3,5-Pr2 Ar Fe[N (1-Ad)]2l [42]. This complex has been characterized by X-ray crystallography with the iron in planar three-coordinate geometry. The Fe-N bond distances are 1.642(2) and 1.619(2)A. Magnetic studies of 3,5-Pr2 Ar Fe[N(l-Ad)]2 reveals that this complex has a low-spin cP configuration with S = jl ground state. This compound is notable as it is a stable Fe(V) imide being well characterized. 

The second complex has been characterized by X-ray crystallography. The ruthenium(II) atom is coordinated to three Me2SO molecules via the oxygen atom and to three via the sulphur atom to give the irregular octahedral geometry as shown in Scheme 18. 

The term persistent is typically applied to long-lived radicals7" which in a majority of cases can be characterized by ESR spectroscopy. " However, the lifetime of those radicals can vary rather broadly from several minutes to months, depending on the environment around the radical center. In this contribution, we will use the terminology of persistent radicals for those radical species with a relatively long lifetime however, those persistent radicals that can be isolated as individual room temperature stable compounds and in many cases characterized by X-ray crystallography will be specifically named as stable radicals (for the chemistry of stable radicals, see Section 2.2.4). 

The structure of the active catalyst and the mechanism of catalysis have not been completely defined. Several solid state complexes of BINOL and Ti(0-/-Pr)4 have been characterized by X-ray crystallography.158 Figure 2.4 shows the structures of complexes having the composition (BIN0Late)Ti2(0-/-Pr)6 and (BINOLate)Ti3(O-/-Pr)10. 

The catalyst used for these mechanistic studies has been characterized by X-ray crystallography, as shown in Figure 5.6. It is obtained as a hydrido ruthenium(II) species that is also coordinated by a [BH4 anion. The catalyst is prepared by exposing the DINAP-diamine RuC12 complex to excess NaBH 54... 

There are relatively few reports of trivalent Tp complexes by comparison with mono- and divalent systems. One interesting example involved transmetallation (from Sn to Co) in the reaction of TpSnCl3 with [Co(CO)4] to give a mixture of products from which [Co(Tp)2][/r[Pg.70]

Iridium(V) complexes, although not common, take a variety of forms, including polynuclear and multidentate structures as well as five-, six- and seven-coordinate species, some of which are stable and have been characterized by X-ray crystallography. 

Treatment of [Ir(coe)2Cl]2 with Ge N(SiMe3)2 2 leads to (62).77 If the reaction proceeds in the presence of CO, then (63) results. Both product species have been characterized by X-ray crystallography. 

The Ir111 cationic pyrazole derivative [Ir(PPh3)2(CO)(dmpzH-N)(H)2]BF4 has been characterized by X-ray crystallography, and shows a roughly octahedral Ir111 center with trans P ligands and cis H ligands.532... 

Reaction of [Ircp Cl2]2 with (MeS)2CH2 and AgBF4 gives [Ircp Cl(/f-(MeS)2CH2)]BF4, whereas treatment with (PhS)2CH2 leads to [Ircp Cl2( 1-(PhS)2CH2], characterized by X-ray crystallography.261... 

The Ir1 silyl complex Ir(PMe3)2(CO)2(SiMe2Ph), (313), is formed by reaction Scheme 29 and is characterized by X-ray crystallography.507 This result shows that metalation of silyl ligands can be a facile, reversible process. 

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