Digital badging at The Open University: recognition for informal learning

Awarding badges to recognise achievement is not a new development. Digital badging now offers new ways to recognise learning and motivate learners, providing evidence of skills and achievements in a variety of formal and informal settings. Badged open courses (BOCs) were piloted in various forms by the Open University (OU) in 2013 to provide a digital acknowledgement for learners’ participation in three entry-level, unsupported courses: Learning to Learn and Succeed with Maths Parts 1 and 2. The desire to build on the OU’s badging pilots is informed by research into the motivations and demographic profiles of learners using the free educational resources which the OU makes available through its OpenLearn platform. This research activity was repeated in 2014 and found that an increasing proportion of informal learners is keen to have their informal learning achievements recognised. This paper outlines how the evaluation of the 2013 pilots has informed the development of a suite of free employability and skills BOCs in 2014 that are assessed through the deployment of Moodle quizzes. It also discusses how the motivational aspects of digital badging support the growth in free, micro-credentialised courses against a backdrop of MOOC providers issuing certification for fee. The BOC project, which aligns with the University’s Journeys from Informal to Formal Learning strategy, will help to provide accessible routes into the University for students who might not otherwise have the opportunity to participate and supports the OU Charter to promote the educational well-being of the community

Structural and functional characteristics of rhenium clusters derived from redox chemistry of the triangular [Re-3(III)(mu-Cl)(3)] core unit

The present study investigates structural and functional aspects of the redox chemistry of rhenium(III) chloride [Re3Cl9] (1) in aqueous and organic solvents, with emphasis on the dioxygen-activating capabilities of reduced rhenium clusters bearing the Re-3(8+) core. Dissolution of 1 in HCl (6 M) generates [Re-3(mu -Cl)(3)Cl-9](3-) (2a), which can be isolated as the tetraphenylphosphonium salt (2b). Anaerobic one-electron reduction of 1 by Hg in HCl (6-12 M) produces [(C6H5)(4)P](2)[Re-3(mu -Cl)(3)Cl-7(H2O)(2)].H2O (3), the structure of which features a planar [Re-3(mu -Cl)(3)Cl-3] framework (Re-3(8+) core), involving two water ligands that occupy out-of-plane positions in a trans arrangement. Compound 3 dissociates in the presence of CO, yielding [(C6H5)(4)P](2)[(Re2Cl8)-Cl-III] (4) and an unidentified red carbonyl species. In situ oxidation (O-2) Of the reduced Re-3(8+)-containing cluster in HCl (6 M) produces quantitatively 2a, whereas oxidation of 3 in organic media results in the formation of [(C6H5)(4)P](4)[Re-3(mu -Cl)(3)Cl-7(mu -OH)(2)]. 2CH(2)Cl(2) (5). The structure of 5 reveals that two oxygen ligands (hydroxo units) bridge asymmetrically two Re-3(9+) triangular clusters. The origin of these hydroxo units derives from the aquo ligands, rather than O-2, as shown by O-18(2) labeling studies. The hydroxo bridges of 5 can be replaced by chlorides upon treatment with Me3SiCl to afford the analogous [(C6H5)(4)P](4)[Re-3(mu -Cl)(3)Cl-7(mu -Cl)(2)]. 10CH(2)Cl(2) (6). The reaction of 5 with Hg in HCl (6 M)/tetrahydrofuran regenerates compound 3. Complexes 1-3 exhibit nitrile hydratase type activity, inducing hydrolysis of CH3CN to acetamide. The reaction of 3 with CH3CN yields [(C6H5)(4)P](2)[Re-3(mu -Cl)(3)Cl-6.5(CH3-CN)(1.5)(CH3C(O)NH)(0.5)] (7), the structure of which is composed of [Re-3(mu -Cl)(3)Cl-7(CH3CN)(2)](2-) (7a) and [Re-3(mu -Cl)(3)Cl(CH3CN)(CH3C(O)NH)](2-) (7b) (Re-3(8+) cores) as a disordered mixture (1:1). Oxidation of 7 with O-2 in CH3CN affords [(C6H5)(4)P](2)[Re-3(mu -Cl)(3)Cl-7(CH3C(O)NH)]. CH3CN (8) and small amounts of [(C6H5)(4)P][ReO4] (9). Compound 8 is also independently isolated from the reaction of 2b with wet CH3CN, or by dissolving 5 in CH3CN. In MeOH, 5 dissociates to afford [(C6H5)(4)P](2)[Re-3(mu -Cl)(3)Cl-8(MeOH)]. MeOH (10)

Structural and Functional Characteristics of Rhenium Clusters Derived from Redox Chemistry of the Triangular [Reᴵᴵᴵ₃(μ-Cl)₃] Core Unit

The present study investigates structural and functional aspects of the redox chemistry of rhenium(III) chloride [Re3Cl9] (1) in aqueous and organic solvents, with emphasis on the dioxygen-activating capabilities of reduced rhenium clusters bearing the Re38+ core. Dissolution of 1 in HCl (6 M) generates [Re3(μ -Cl)3Cl9]3- (2a), which can be isolated as the tetraphenylphosphonium salt (2b). Anaerobic one-electron reduction of 1 by Hg in HCl (6− 12 M) produces [(C6H5)4P]2[Re3(μ -Cl)3Cl7(H2O)2]·H2O (3), the structure of which features a planar [Re3(μ -Cl)3Cl3] framework (Re38+ core), involving two water ligands that occupy out-of-plane positions in a trans arrangement. Compound 3 dissociates in the presence of CO, yielding [(C6H5)4P]2[ReIII2Cl8] (4) and an unidentified red carbonyl species. In situ oxidation (O2) of the reduced Re38+-containing cluster in HCl (6 M) produces quantitatively 2a, whereas oxidation of 3 in organic media results in the formation of [(C6H5)4P]4[{Re3(μ -Cl)3Cl7(μ -OH)}2]·2CH2Cl2 (5). The structure of 5 reveals that two oxygen ligands (hydroxo units) bridge asymmetrically two Re39+ triangular clusters. The origin of these hydroxo units derives from the aquo ligands, rather than O2, as shown by 18O2 labeling studies. The hydroxo bridges of 5 can be replaced by chlorides upon treatment with Me3SiCl to afford the analogous [(C6H5)4P]4[{Re3(μ -Cl)3Cl7(μ -Cl)}2]·10CH2Cl2 (6). The reaction of 5 with Hg in HCl (6 M)/tetrahydrofuran regenerates compound 3. Complexes 1− 3 exhibit nitrile hydratase type activity, inducing hydrolysis of CH3CN to acetamide. The reaction of 3 with CH3CN yields [(C6H5)4P]2[Re3(μ -Cl)3Cl6.5(CH3CN)1.5(CH3C(O)NH)0.5] (7), the structure of which is composed of [Re3(μ -Cl)3Cl7(CH3CN)2]2- (7a) and [Re3(μ -Cl)3Cl6(CH3CN)(CH3C(O)NH)]2- (7b) (Re38+ cores) as a disordered mixture (1:1). Oxidation of 7 with O2 in CH3CN affords [(C6H5)4P]2[Re3(μ -Cl)3Cl7(CH3C(O)NH)]·CH3CN (8) and small amounts of [(C6H5)4P][ReO4] (9). Compound 8 is also independently isolated from the reaction of 2b with wet CH3CN, or by dissolving 5 in CH3CN. In MeOH, 5 dissociates to afford [(C6H5)4P]2[Re3(μ -Cl)3Cl8(MeOH)]·MeOH (10)

Synthesis, Characterization, and Reactivity of Iron Trisamidoamine Complexes That Undergo Both Metal- and Ligand-centered Oxidative Transformations

Functional systems that combine redox-active metals and noninnocent ligands are no longer rare chemical oddities; they are instead emerging as significant components of catalytic and enzymatic reactions. The present work examines the synthetic and functional aspects of iron compounds ligated by a family of new trisamidoamine ligands of the type [(RNC6H4) 3N]3- (L1). When R is the electron-rich 4-t-Bu-Ph moiety, the ligand can undergo oxidative rearrangement and store oxidizing equivalents under specific conditions. Starting ferrous complexes of the general formula [(L1)FeIIsolv]- (solv = CH3CN, dimethylformamide) can be easily oxidized (a) by dioxygen to afford the corresponding [(L1)FeIIIOH]- complexes, featuring several cases of terminal hydroxo units, and (b) by organochlorides (R-Cl) to provide [(L1)FeIIIsolv] congeners and coupled R-R products. Efforts to synthesize [(L 1)FeIII-O-FeIII(L1)]2- by using [Cl3FeIII-O-FeIIICl3] 2- indicate that intrinsic FeIIICl units can oxidatively rearrange the ligand to afford [(L1 re)(Cl)Fe II][Et4N]2, although the oxidizing equivalent is not retained. Compound [(L1 re)(Cl)Fe II][Et4N]2 can be further oxidized to [(L 1 re-2)(Cl)FeIII][Et4N] by CH 2Cl2. Finally, oxidation of [(L1)Fe IIIsolv] by FeCl3 affords [(L1 reH)(Cl)FeII(μ -Cl)2FeII(Cl) (L1 re-2H)], which features a similar ligand rearrangement that also gives rise to a diamagnetic, doubly oxidized moiety. These results underscore the complexity of chemical transformations available to systems in which both the metal and the ligand are redox-active entities

Synthesis, Characterization, and Reactivity of Iron Trisamidoamine Complexes That Undergo Both Metal- and Ligand-Centered Oxidative Transformations

Functional systems that combine redox-active metals and noninnocent ligands are no longer rare chemical oddities; they are instead emerging as significant components of catalytic and enzymatic reactions. The present work examines the synthetic and functional aspects of iron compounds ligated by a family of new trisamidoamine ligands of the type [(RNC6H4)(3)N](3-) (L-1). When R is the electron-rich 4-t-Bu-Ph moiety, the ligand can undergo oxidative rearrangement and store oxidizing equivalents under specific conditions. Starting ferrous complexes of the general formula [(L-1)Fe(II)solv](-) (solv = CH3CN, dimethylformamide) can be easily oxidized (a) by dioxygen to afford the corresponding [(L-1)(FeOH)-O-III](-) complexes, featuring several cases of terminal hydroxo units, and (b) by organochlorides (R-Cl) to provide [(L-1)Fe(III)solv] congeners and coupled R-R products. Efforts to synthesize [(L-re(1))Fe-III-O-Fe-III(L-1)](2-) by using [Cl3FeIII-O-(FeCl3)-Cl-III](2-) indicate that intrinsic (FeCl)-Cl-III units can oxidatively rearrange the ligand to afford [(L-re(1))(Cl)Fe-II][Et4N](2), although the oxidizing equivalent is not retained. Compound [(L-re(1)) (Cl) Fe-II][Et4N](2) can be further oxidized to [(L-re-2(1))(Cl)Fe-III][Et4N] by CH2Cl2. Finally, oxidation of [(L-1)Fe(III)solv] by FeCl3 affords [((LreH)-H-1)(Cl)Fe-II(mu-Cl)(2)Fe-II(Cl)((Lre-2H)-H-1)], which features a similar ligand rearrangement that also gives rise to a diamagnetic, doubly oxidized moiety. These results underscore the complexity of chemical transformations available to systems in which both the metal and the ligand are redox-active entities

Metalloradical Complexes of Manganese and Chromium Featuring an Oxidatively Rearranged Ligand

Redox events involving both metal and ligand sites are receiving increased attention since a number of biological processes direct redox equivalents toward functional residues. Metalloradical synthetic analogues remain scarce and require better definition of their mode of formation and subsequent operation. The trisamido-amine ligand [(RNC6H4)3N] 3-, where R is the electron-rich 4-t-BuPh, is employed in this study to generate redox active residues in manganese and chromium complexes. Solutions of [(L1)Mn(II)-THF]- in THF are oxidized by dioxygen to afford [(L1re-1)Mn(III)-(O)2-Mn(III)(L 1re-1)]2- as the major product. The rare dinuclear manganese (III,III) core is stabilized by a rearranged ligand that has undergone an one-electron oxidative transformation, followed by retention of the oxidation equivalent as a π radical in an o-diiminobenzosemiquinonate moiety. Magnetic studies indicate that the ligand-centered radical is stabilized by means of extended antiferromagnetic coupling between the S = 1/2 radical and the adjacent S = 2 Mn(III) site, as well as between the two Mn(III) centers via the dioxo bridge. Electrochemical and EPR data suggest that this system can store higher levels of oxidation potency. Entry to the corresponding Cr(III) chemistry is achieved by employing CrCl3 to access both [(L 1)Cr(III)-THF] and [(L1re-1)Cr(III)-THF(CI)], featuring the intact and the oxidatively rearranged ligands, respectively. The latter is generated by ligand-centered oxidation of the former compound. The rearranged ligand is perceived to be the product of an one-electron oxidation of the intact ligand to afford a metal-bound aminyl radical that subsequently mediates a radical 1,4-(N-to-N) aryl migration

Oxidative Ligand Rearrangement Due to Incipient Aminyl Radicals in the Oxidation of Iron(II) Species with Dioxygen

The ferrous complex [(L1)FeII-THF]-, featuring the trisamidoamine ligand [(RNC6H4) 3N]3-, where R is the electron-rich 4-tBu-Ph moiety, can undergo a one-electron oxidation by dioxygen to afford the corresponding [(L1)FeIII-OH]- complex, and a parallel two-electron oxidation to generate the antiferromagnetically coupled diferric μ -oxo compound [(L1 re-1)Fe-O-Fe(L1 re-1)]. The latter compound possesses a ligand that exhibits oxidative rearrangement and retention of the oxidation equivalent in a o-diiminobenzosemiquinato moiety as a π radical. Ligand oxidation is perceived to initiate at an amido residue leading to formation of an electrophilic, metal-bould aminyl radical that undergoes an 1,4-(N-to-N) aryl migration reaction

Oxidative ligand rearrangement due to incipient aminyl radicals in the oxidation of iron(II) species with dioxygen

The ferrous complex [(L-1)Fe-II-THF](-), featuring the trisamido-amine ligand [(RNC6H4)(3)N](3-), where R is the electron-rich 4-tBu-Ph moiety, can undergo a one-electron oxidation by dioxygen to afford the corresponding [(L-1)Fe-III-OH](-) complex, and a parallel two-electron oxidation to generate the antiferromagnetically coupled diferric mu-oxo compound [(L-re-1(1))Fe-O-Fe(L-re-1(1))]. The latter compound possesses a ligand that exhibits oxidative rearrangement and retention of the oxidation equivalent in a o-diiminobenzosemiquinato moiety as a pi radical. Ligand oxidation is perceived to initiate at an amido residue leading to formation of an electrophilic, metal-bould aminyl radical that undergoes an 1,4-(N-to-N) aryl migration reaction. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)