Gyroscope like molecules consisting of trigonal or square planar osmium rotators within three-spoked dibridgehead diphosphine stators: syntheses, substitution reactions, structures, and dynamic properties

Reactions of (NH4)2OsX6 (X = Cl, Br) with CO and the phosphines P((CH2)mCH[double bond, length as m-dash]CH2)3 (m = 6, a; 7, b; 8, c) give cis,cis,trans-Os(CO)2(X)2(P((CH2)mCH[double bond, length as m-dash]CH2)3)2 (46–73%). These are treated with Grubbs’ catalyst (7 mol%, 0.0010 M, C6H5Cl). Subsequent hydrogenations (PtO2) yield the gyroscope like complexes cis,cis,trans-Os(CO)2(X)2(P((CH2)n)3P) (n = 2m + 2; X = Cl, 6a–c; Br, 7a–c; 5–31%) and the isomers cis,cis,trans-Os(CO)2(X)2(P(CH2)n−1CH2)((CH2)n)(P(CH2)n−1CH2) (X = Cl, 6′a–c; Br, 7′a–c; 12–51%) derived from a combination of interligand and intraligand metatheses. Reductions of 6a,c, 6′b, and 7′b with C8K under CO atmospheres afford trans-Os(CO)3(P((CH2)n)3P) (9a,c, 79–82%) and trans-Os(CO)3(P(CH2)15CH2)((CH2)16)(P(CH2)15CH2) (9′b, 53–84%). Reaction of 9a and CF3SO3H yields the cationic hydride complex mer,trans-[Os(H)(CO)3(P((CH2)14)3P)]+ CF3SO3− (9a-H+ CF3SO3−; quantitative by NMR). Preparative reactions of 9a,c or 9′b and [H(OEt2)2]+ BArf− (BArf− = B(3,5-C6H3(CF3)2)4−) afford 9a,c-H+ BArf− (80%) or 9′b-H+ BArf− (68%). Reactions of 6a, 6′b, and 7a with MeLi or PhLi give cis,cis,trans-Os(CO)2(Me)2(P((CH2)14)3P) (11a, 98%), cis,cis,trans-Os(CO)2(Me)2(P(CH2)15CH2)((CH2)16)(P(CH2)15CH2) (98%), and cis,cis,trans-Os(CO)2(Ph)2(P((CH2)14)3P) (12a, 58%). NMR data for 6a–c, 7a–c, 9a,c, 9a,c-H+ X−, and 11a indicate that rotation of the OsLy moieties is fast on the NMR time scale at room temperature. In contrast, the phenyl groups in 12a act as “brakes” and two sets of 13C NMR signals are observed for the methylene chains (2 : 1). The crystal structures of 6a–c, 7b,c, 7′a, 9a, 9a-H+ BArf−, 11a, and 12a are analyzed with respect to OsLy rotation in solution and the solid state

Redox active iron nitrosyl units in proton reduction electrocatalysis

Base metal, molecular catalysts for the fundamental process of conversion of protons and electrons to dihydrogen, remain a substantial synthetic goal related to a sustainable energy future. Here we report a diiron complex with bridging thiolates in the butterfly shape of the 2Fe2S core of the [FeFe]-hydrogenase active site but with nitrosyl rather than carbonyl or cyanide ligands. This binuclear [(NO)Fe(N_2S_2)Fe(NO)_2]+ complex maintains structural integrity in two redox levels; it consists of a (N_2S_2)Fe(NO) complex (N_2S_2=N,N′-bis(2-mercaptoethyl)-1,4-diazacycloheptane) that serves as redox active metallodithiolato bidentate ligand to a redox active dinitrosyl iron unit, Fe(NO)_2. Experimental and theoretical methods demonstrate the accommodation of redox levels in both components of the complex, each involving electronically versatile nitrosyl ligands. An interplay of orbital mixing between the Fe(NO) and Fe(NO)_2 sites and within the iron nitrosyl bonds in each moiety is revealed, accounting for the interactions that facilitate electron uptake, storage and proton reduction

Synthesis and X-ray Analysis of (RS)-N-tert-butyl-2-anilino- 3,3-dimethylbutanamide

The crystal and molecular structure of (RS)-N-Tert-butyl-2-anilino-3,3-dirnethylbutanamide, a derivative of an amino acid that was obtained by highly selective cleavage of 1,3-di-tert-butylaziridinone by aniline, is described. The racemic mixture of the amide crystallizes in the space grot)p P 2in with four molecules per unit cell. Crystal Data: a - 10.483(2) A, h - 6.206(I) A, c = 24.767(5) A, [3 - 90.39(3), V = 1611.5(6) A ~, R(F)[I > 2r = 0.0679, wR(F 2) [1 > 2or(l)] = 0. 1148