The d 6 complexes of formula (η 5 -Cp)Ru(CO)(ER 3 )ONO 2 , where ER 3 ) AsPh 3 , PPh 3 , P(panisyl) 3 , PPh 2 (o-anisyl), and P(OPh) 3 , were prepared by reaction of their chloro analogues with AgNO 3 in CH 2 Cl 2 . They underwent moderately slow substitution of the relatively weakly coordinating nitrate by chloride in dry CH 2 Cl 2 in the presence of excess [N(PPh 3 ) 2 + ]Cl -. A kinetics study showed the reaction to be first order in nitrato complex and independent of chloride salt concentration under pseudo-first-order conditions. First-order rate constants for nitrate metathesis follow the trend P(OPh) 3 < PPh 3 < P(p-anisyl) 3 < AsPh 3 , PPh 2 (oanisyl), with k 1 at 25 °C for the first four in the series from 1.4 to 4.4 × 10 -5 s -1 . Activation parameters for conversion of (η 5 -Cp)Ru(CO)(AsPh 3 )ONO 2 to its chloride are ∆H ‡ ) 17(2) kcal/mol and ∆S ‡ ) -21(5) eu. Even use of a slightly moist solvent increased the rate of nitrate metathesis by 20-30% without changing the form of the rate law. The complex containing PPh 2 (o-anisyl) was approximately 2 orders of magnitude more reactive (k 1 ) 4.9 × 10 -3 s -1 ). A likely explanation is stabilization of a coordinatively unsaturated intermediate by weak coordination of the potentially chelating o-OMe group. A mechanism entailing ratelimiting conversion of the neutral nitrato complex into a coordinatively unsaturated ionpaired species is consistent with this set of data. Semiempirical calculations (PM3(tm)), which model the structures of complexes in these systems quite well, supported such behavior. X-ray crystal structures were determined for the AsPh 3 nitrato and chloro complexes and for the PPh 3 chloro complex.

A practical synthesis of the purine nucleoside phosphorylase (PNP) inhibitor BCX-4208 (1) was accomplished in three telescoped steps. Mannich condensation of the 4-benzyloxy-9-deazahypoxanthine with (3R,4R)-3-hydroxy-4-(hydroxymethyl)pyrrolidine and formaldehyde followed by removal of the protecting group and crystallization furnished the desired product as a hydrochloride salt in 85% overall yield and 99.8% purity. A scalable synthesis of 9-deazahypoxanthine is also reported.

The long-term storage of human and animal cell lines is a relatively new branch of the science of cryopreservation of living organisms. The need to maintain the increasing numbers of cell lines, as they started to emerge from research laboratories from the mid-1900s, necessitated a radical approach to the problem. The realization that they could survive cryopreservation, and that a slow rate of cooling is essential for this survival, led to the eventual discovery of cryoprotectants. Subsequent development of mechanical freezers, which can accurately control the rate of cooling, now allows cells to be cryopreserved at their maximum viability. This chapter outlines the essentials steps for the successful preparation, freezing, and storage of cell lines.

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The N-terminal 40 amino acid sequences of the small subunit of ribulose bisphosphate carboxylase have been determined for 13 species of Solanum, one other species of Solanaceae and two of Convolvulaceae. From these, and previously published sequences from Solanaceae, a minimal phylogenetic tree is derived. This agrees well with current taxonomy; the first dichotomy in the Solanaceae tree is between the two subfamilies Solanoideae and Cestroideae; within Solanum the subgenera Solanum and Leptostemonum separate dichotomously; within subgenus Leptostemonum the African and Asian species diverge from the Australian. Within the Australian species of subgenus Leptostemonum two most unusual substitutions have been noted. The implications for the hypotheses of a 'molecular evolutionary clock' and of biogeographical dispersal by continental drift are discussed.