Treatment of CrCl 2 (THF) 2 with NaOSi t Bu 3 afforded the butterfly dimer [( t Bu 3 SiO)Cr] 2 (µ-OSi t Bu 3 ) 2 (1 2 ), whose d(CrCr) of 2.658(31) Å and magnetism were indicative of strong antiferromagnetic coupling. A Boltzmann distribution of low-energy 1 A

Treatment of trans-(Et2O)2MoCl4 with 2 or 3 equiv of Na(silox) (i.e., NaOSi t Bu3) afforded (silox)3MoCl2 (1-Mo) or (silox)3MoCl (2-Mo). Purification of 2-Mo was accomplished via addition of PMe3 to precipitate (silox)3ClMoPMe3 (2-MoPMe3), followed by thermolysis to remove phosphine. Use of MoCl3(THF)3 with various amounts of Na(silox) produced (silox)2ClMoMoCl(silox)2 (3-Mo). Alkylation of 2-Mo with MeMgBr or EtMgBr afforded (silox)3MoR (R = Me, 2-MoMe; Et, 2-MoEt). 2-MoEt was also synthesized from C2H4 and (silox)3MoH, which was prepared from 2-Mo and NaBEt3H. Thermolysis of WCl6 with HOSi t Bu3 afforded (silox)2WCl4 (4-W), and sequential treatment of 4-W with Na/Hg and Na(silox) provided (silox)3WCl2 (1-W, tbp, X-ray), which was alternatively prepared from trans-(Et2S)2WCl4 and 3 equiv of Tl(silox). Na/Hg reduction of 1-W generated (silox)3WCl (2-W). Alkylation of 2-W with MeMgBr produced (silox)3WMe (2-WMe), which dehydrogenated to (silox)3WCH (6-W) with ΔH ‡ = 14.9(9) kcal/mol and ΔS ‡ = −26(2) eu. Magnetism and structural studies revealed that 2-Mo and 2-MoEt have triplet ground states (GS) and distorted trigonal monopyramid (tmp) and tmp structures, respectively. In contrast, 2-W and 2-WMe possess squashed-Td (distorted square planar) structures, and the former has a singlet GS. Quantum mechanics/molecular mechanics studies of the S = 0 and S = 1 states for full models of 2-Mo, 2-MoEt, 2-W, and 2-WMe corroborate the experimental findings and are consistent with the greater nd z 2 /(n + 1)s mixing in the third-row transition-metal species being the dominant feature in determining the structural disparity between molybdenum and tungsten.

One of the essential elements of any cell, including primitive ancestors, is a structural component that protects and confines the metabolism and genes while allowing access to essential nutrients. For the targeted protocell model, bilayers of decanoic acid, a single-chain fatty acid amphiphile, are used as the container. These bilayers interact with a ruthenium-nucleobase complex, the metabolic complex, to convert amphiphile precursors into more amphiphiles. These interactions are dependent on non-covalent bonding. The initial rate of conversion of an oily precursor molecule into fatty acid was examined as a function of these interactions. It is shown that the precursor molecule associates strongly with decanoic acid structures. This results in a high dependence of conversion rates on the interaction of the catalyst with the self-assembled structures. The observed rate logically increases when a tight interaction between catalyst complex and container exists. A strong association between the metabolic complex and the container was achieved by bonding a sufficiently long hydrocarbon tail to the complex. Surprisingly, the rate enhancement was nearly as strong when the ruthenium and nucleobase elements of the complex were each given their own hydrocarbon tail and existed as separate molecules, as when the two elements were covalently bonded to each other and the resulting molecule was given a hydrocarbon tail. These results provide insights into the possibilities and constraints of such a reaction system in relation to building the ultimate protocell.

Treatment of (silox)3MCl (M ) Mo, 1-Cl; W, 2-Cl; silox ) t Bu3SiO) with PMe3 and Na/Hg led to formation of monomeric, d3 phosphine adducts, (silox)3MPMe3 (M ) Mo, 1-PMe3; W, 2-PMe3) via (silox) 3ClMPMe3 (M ) Mo, 1-ClPMe3; W, 2-ClPMe3). Structural studies show 1-PMe3 and 2-PMe3 to be highly distorted; calculations on full chemical models corroborate experimentally determined S ) 1 /2 ground states and their structural features. The compounds contain a bent M-P bond that is characteristic of significant σ/π-mixing. PMe 3 may be thermally removed from 1-PMe3 in vacuo to produce 4 A2′ (silox)3Mo (1), which was derivatized with CO, NO, and 1/4 P 4 to form (silox)3Mo (1-CO), (silox)3MoNO (1-NO), and (silox) 3MoP (1-P), respectively. Calculations revealed (silox)3W (2′) to have an S ) 1 /2 ground state, which may render it too reactive to be isolated. Treatment of 2-PMe 3 with CO, NO, and 1/4 P4 formed (silox)3WCO (2-CO), (silox) 3WNO (2-NO), and (silox)3WP (2-P), respectively. 2-CO and 2-NO are more conveniently prepared from Na/Hg reductions of 2-Cl in the presence of CO and NO, respectively. Calculations reveal subtle effects of nd z 2/(n+1)s mixing in differentiating the chemistry of Mo and W and in rationalizing the generation of mononuclear species.