The ensemble of forces that stabilize protein structure and facilitate biological function are intimately linked with the ubiquitous aqueous environment of living systems. As a consequence, biomolecular activity is highly sensitive to the interplay of solvent-protein interactions, and deviation from the native conditions, for example by exposure to increased thermal energy or severe dehydration, results in denaturation and subsequent loss of function. Although certain enzymes can be extracted into non-aqueous solvents without significant loss of activity, there are no known examples of solvent-less (molten) liquids of functional metalloproteins. Here we describe the synthesis and properties of room-temperature solvent-free myoglobin liquids with near-native structure and reversible dioxygen binding ability equivalent to the haem protein under physiological conditions. The realization of room-temperature solvent-free myoglobin liquids with retained function presents novel challenges to existing theories on the role of solvent molecules in structural biology, and should offer new opportunities in protein-based nanoscience and bionanotechnology.

Six- and five-coordinate Fe(II) complexes with the pincer ligand 2,6-bis(imidazolylidene)pyridine (C−N−C), [(C−N−C)Fe(MeCN)3][BPh4]2 and [(C−N−C)FeBr2], respectively, were synthesized. Substitution of tmeda in [FeCl2(tmeda)]2 by C−N−C gave the six-coordinate {[Fe(C−N−C)(C−N−C*)][FeCl4]}, in which one of the pincer ligands is bound to the metal via the 2- and 5-imidazole carbons.

The addition of H(2) across a transition metal-borane bond is reported for the first time providing a mechanism for recharging borane functional groups to borohydride.

The (diphenylphosphino)alkyl-functionalized nucleophilic heterocyclic carbene (NHC) complexes of palladium LPdX2 (L = (3-R1)[1-Ph2P(CH2)2]-imidazol-2-ylidene; R1 = 2,6-Pri 2C6H3, 2,4,6-Me3C6H2; X = CH3 (3a,b), X = Br (4a,b)) have been synthesized by the reaction of the in situ generated functionalized NHC ligand L a or L b with Pd(tmed)(CH3)2 and Pd(COD)Br2, respectively, and structurally characterized. Interaction of 3a with H(Et2O){B[3,5-(CF3)2C6H2]4} and pyridine or with (CF3)2CHOH and pyridine in CH2Cl2 gave the monocationic complexes [(La)Pd(CH3)(pyridine)]+(A)- (A- = {B[(3,5-CF3)2C6H2)]4}-, (CF3)2CHO-); acetonitrile and benzonitrile analogues can be prepared in an analogous way. Reaction of 4a with AgBF4 in MeCN gave the dicationic complexes [(La)Pd(MeCN)2](BF4)2. Complexes 3 show moderate catalytic activity for the coupling of acrylates with aryl bromides but not chlorides. The cationic species generated in situ from 3a and H(Et2O){B[(3,5-CF3)2C6H2)]4} in CH2Cl2 under CO/ethylene acts as a copolymerization catalyst under mild conditions.