Co(II/III) coordinated pyridine alcoholate ligand generated through metal assisted nucleophilic addition to a CO function: Temperature dependent synthesis of a mononuclear complex and a neutral cubane cluster

Crystal structure of bis(hydroxydi(pyridin-2-yl)methanolato-κ3 N,N′O)cobalt(III) 7,7,8,8-tetracyanoquinodimethane, C34H22CoN8O4

C34H22CoN8O4, triclinic, P1̄ (no. 2), a = 6.8423(10) Å, b = 8.8919(13) Å, c = 12.6319(18) Å, α = 104.743(2)°, β = 94.606(2)°, γ = 90.934(2)°, V = 740.30(19) Å3, Z = 1, R gt(F) = 0.0369, wRref(F 2) = 0.1179, T = 296(2) K.

Mechanistically Driven Control over Cubane Oxo Cluster Catalysts

Predictive and mechanistically driven access to polynuclear oxo clusters and related materials remains a grand challenge of inorganic chemistry. We here introduce a novel strategy for synthetic control over highly sought-after transition metal {M₄O₄} cubanes. They attract interest as molecular water oxidation catalysts that combine features of both heterogeneous oxide catalysts and nature's cuboidal {CaMn₄O₅} center of photosystem II. For the first time, we demonstrate the outstanding structure-directing effect of straightforward inorganic counteranions in solution on the self-assembly of oxo clusters. We introduce a selective counteranion toolbox for the controlled assembly of di(2-pyridyl) ketone (dpk) with M(OAc)₂ (M = Co, Ni) precursors into different cubane types. Perchlorate anions provide selective access to type 2 cubanes with the characteristic {H₂O-M₂(OR)₂-OH₂} edge-site, such as [Co₄(dpy-C{OH}O)₄(OAc)₂(H₂O)₂](ClO₄)₂. Type 1 cubanes with separated polar faces [Co₄(dpy-C{OH}O)₄(L2)₄] ⁿ⁺ (L2 = OAc, Cl, or OAc and H₂O) can be tuned with a wide range of other counteranions. The combination of these counteranion sets with Ni(OAc)₂ as precursor selectively produces type 2 Co/Ni-mixed or {Ni₄O₄} cubanes. Systematic mechanistic experiments in combination with computational studies provide strong evidence for type 2 cubane formation through reaction of the key dimeric building block [M₂(dpy-C{OH}O)₂(H₂O)₄]²⁺ with monomers, such as [Co(dpy-C{OH}O)(OAc)(H₂O)₃]. Furthermore, both experiments and DFT calculations support an energetically favorable type 1 cubane formation pathway via direct head-to-head combination of two [Co₂(dpy-C{OH}O)₂(OAc)₂(H₂O)₂] dimers. Finally, the visible-light-driven water oxidation activity of type 1 and 2 cubanes with tuned ligand environments was assessed. We pave the way to efficient design concepts in coordination chemistry through ionic control over cluster assembly pathways. Our comprehensive strategy demonstrates how retrosynthetic analyses can be implemented with readily available assembly directing counteranions to provide rapid access to tuned molecular materials.

Crystal structure of bis(hydroxydi(pyridin-2-yl)methanolato-κ3 N,N′,O)cobalt(III) perchlorate dihydrate, C22H22ClCoN4O10

C22H22ClCoN4O10, triclinic, P1̄ (no. 2), a = 8.4566(7) Å, b = 11.9163(7) Å, c = 12.4333(9) Å, α = 99.770(1)°, β = 103.490(1)°, γ = 90.290(1)°, V = 1199.38(15) Å3, Z = 2, R gt(F) = 0.0295, wR ref(F 2) = 0.0774, T = 150 K.

Organoplatinum(IV) complexes with functional alkyl groups and their use in supramolecular chemistry

The oxidative addition of alkyl bromides RCH2Br (R = C5H4N, C6H4CN, CH2C6H4CO2H, or CH2C6H4CH2CO2H) to dimethylplatinum(II) complexes [PtMe2(LL)] (LL = diimine ligand) gives the corresponding organoplatinum(IV) complexes [PtBrMe2(CH2R)(LL)] containing functionality in the alkyl group RCH2. The pyridyl derivatives can be protonated, while abstraction of the bromide ligand from [PtBrMe2(CH2R)(LL)] can form cationic complexes, which can react with water or form oligomers by self-assembly.