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Background: Previous studies linked metformin use to vitamin B12 deficiency and demonstrated that the prevalence of vitamin B12 monitoring remains low. Objective: This study aimed to assess the occurrence of monitoring vitamin B12 levels in a diverse population. Methods: This was a retrospective chart review of adult patients with type 2 diabetes on metformin doses ≥ 1000 mg for ≥ 6 months at five Federally Qualified Health Centers (FQHC) and one Program of All-Inclusive Care for the Elderly (PACE). Charts were reviewed for occurrence of monitoring vitamin B12 levels in the past 5 years. Data collected included patient demographics, laboratory data, other potential vitamin B12 level lowering agents, active prescription for vitamin B12 supplementation, concomitant diabetes medications and metformin total daily dose. Results: Of the 322 patients included, 25% had a vitamin B12 level measured in the previous five years. Among the patients with a vitamin B12 level, 87.7% were within the normal range (>350 pg/mL), 11.1% were low (200-300 pg/mL), and only one patient (1.2%) was deficient (

Sulfated zirconium oxide (SZO) catalyzes the hydrogenolysis of isotactic polypropylene (iPP, M w =13.3 kDa, Đ=2.4, =94 %) or high-density polyethylene (HDPE, M n =2.5 kDa, Đ=3.6) to branched alkane products. We propose that this reactivity is driven by the pyrosulfate sites SZO, which open under mild conditions to transiently form adsorbed SO 3 and sulfate groups. This adsorbed SO 3 is a very strong Lewis acid that binds 15 N-pyridine or triethylphosphineoxide (TEPO) (ΔE ads >-39 kcal mol -1 ), reacts with Ph 3 CH to form Ph 3 C + , and mediates H/D exchange in dihydroanthracene-d 4 . DFT studies show that pyrosulfate sites open with a modest 26.1 kcal mol -1 barrier to form the adsorbed SO 3 and sulfate in the presence of a tetramer of propylene. Hydride abstraction from the tertiary C-H in this model is exothermic and subsequent β-scission forms cleaved products. Analysis of the energetics provided here brackets the hydride ion affinity (HIA) of the adsorbed SO 3 between 226.2 to 237.9 kcal mol -1 , among largest values reported for a formally neutral Lewis acid. This study explains how SZO, a classic heterogeneous catalyst, can form carbocations by a redox neutral hydride abstraction reaction by very strong Lewis sites., (© 2024 Wiley-VCH GmbH.)

The fluorinated alcohols, (CF 3 ) 3 COH (R F9 OH) and (CF 3 ) 2 MeCOH (R F6 OH), react with W(NR) 2 Cy 2 (Cy=Cyclohexyl; R=2,6-diisopropylphenyl or 1-adamantyl) in C 6 D 6 at 55 °C to give cyclohexylidene complexes. Traditional routes to terminal alkylidene complexes (neopentylidene or neophylidene) have used either triflic acid or HCl (rarely), but relatively weak fluorinated acids are sufficient and active bisalkoxide catalysts are therefore prepared directly. An α hydrogen abstraction reaction to give a cyclohexylidene complex from a biscyclohexyl complex appears to be as facile as α hydrogen abstraction to give a neopentylidene or neophylidene ligand, but isomerization of a cyclohexene formed through β hydrogen abstraction is also a possibility. The OR F9 ligands can be replaced readily with dimethylpyrrolide (Me 2 Pyr) or other more basic alkoxides. Single crystal X-ray studies were carried out on W(NAr) 2 Cy 2 , W(NAr)(OR F9 ) 2 (C 6 H 10 )(ArNH 2 ), W(NAr)(OR F6 ) 2 (C 6 H 10 )(ArNH 2 ), W(NAd)(OR F9 ) 2 (C 6 H 10 )(AdNH 2 ), W(NAr)(O-i-Pr F6 ) 3 Cy, and W(NAd)(η 1 -Me 2 Pyr) 2 (C 6 H 10 ) (C 6 H 10 =cyclohexylidene)., (© 2024 Wiley-VCH GmbH.)

A 7-tungstabicyclo[4.3.0]nonane complex forms slowly upon addition of cyclohexene to the ethylene complex, W(NAr)(OSiPh 3 ) 2 (C 2 H 4 ), at 22 °C. A single-crystal X-ray study showed its structure to be closest to a square pyramid (τ = 0.23). At 22 °C, loss of cyclohexene or ring contraction of the 7-tungstabicyclo[4.3.0]nonane complex is slow. Above ∼80 °C, cyclohexene is ejected to give W(NAr)(OSiPh 3 ) 2 (C 2 H 4 ), but a sufficient amount of 7-tungstabicyclo[4.3.0]nonane complex remains in the presence of cyclohexene and the ring contracts to yield methylenecyclohexane and a methylidene complex or ethylene and a cyclohexylidene complex. Other complexes that have been observed include an 8-tungstabicyclo[4.3.0]nonane complex formed from 1,7-octadiene, a 7-tungstabicyclo[4.2.0]octane complex (formed from a methylidene complex and cyclohexene), and a methylenecyclohexane complex. 13 C-Labeling studies show that the exo-methylene group in methylenecyclohexane and the α positions in the 8-tungstabicyclo[4.3.0]nonane come from ethylene. An alternative ring contraction of a tungstacyclopentane made from two molecules of cyclohexene cannot be excluded when concentrations of ethylene are low. A cyclohexylidene complex could also form from two cyclohexenes via a newly proposed "alkyl/allyl" mechanism. The results reported here are the first experimental confirmations that a tungstacyclopentane can ring-contract thermally at a substituted WC α position to form a tungstacyclobutane and therefore metathesis-active alkylidenes.

Bis(1-methyl- ortho -carboranyl)borane (HB Me o Cb 2 ) is a very strong Lewis acid that reacts with the isolated silanols present on silica partially dehydroxylated at 700 °C (SiO 2-700 ) to form the well-defined Lewis site Me o Cb 2 B(OSi≡) ( 1 ) and H 2 . 11 B{ 1 H} magic-angle spinning (MAS) nuclear magnetic resonance (NMR) data of 1 are consistent with that of a three-coordinate boron site. Contacting 1 with O═PEt 3 (triethylphosphine oxide TEPO) and measuring 31 P{ 1 H} MAS NMR spectra show that 1 preserves the strong Lewis acidity of HB Me o Cb 2 . Hydride ion affinity and fluoride ion affinity calculations using small molecules analogs of 1 also support the strong Lewis acidity of the boron sites in this material. Reactions of 1 with Cp 2 Hf( 13 CH 3 ) 2 show that the Lewis sites are capable of abstracting methide groups from Hf to form [Cp 2 Hf- 13 CH 3 ][H 3 13 C-B( Me o Cb 2 )OSi≡], but with a low overall efficiency.

Characterization of paramagnetic compounds, in particular regarding the detailed conformation and electronic structure, remains a challenge, and - still today it often relies solely on the use of X-ray crystallography, thus limiting the access to electronic structure information. This is particularly true for lanthanide elements that are often associated with peculiar structural and electronic features in relation to their partially filled f-shell. Here, we develop a methodology based on the combined use of state-of-the-art magnetic resonance spectroscopies (EPR and solid-state NMR) and computational approaches as well as magnetic susceptibility measurements to determine the electronic structure and geometry of a paramagnetic Yb(III) alkyl complex, Yb(III)[CH(SiMe 3 ) 2 ] 3 , a prototypical example, which contains notable structural features according to X-ray crystallography. Each of these techniques revealed specific information about the geometry and electronic structure of the complex. Taken together, both EPR and NMR, augmented by quantum chemical calculations, provide a detailed and complementary understanding of such paramagnetic compounds. In particular, the EPR and NMR signatures point to the presence of three-centre-two-electron Yb-γ-Me-β-Si secondary metal-ligand interactions in this otherwise tri-coordinate metal complex, similarly to its diamagnetic Lu analogues. The electronic structure of Yb(III) can be described as a single 4f 13 configuration, while an unusually large crystal-field splitting results in a thermally isolated ground Kramers doublet. Furthermore, the computational data indicate that the Yb-carbon bond contains some π-character, reminiscent of the so-called α-H agostic interaction.

Cp 2 Hf(CH 3 ) 2 reacts with silica containing strong aluminum Lewis sites to form Cp 2 Hf- 13 CH 3 + paired with aluminate anions. Solid-state NMR studies show that this reaction also forms neutral organohafnium and hafnium sites lacking methyl groups. Cp 2 Hf- 13 CH 3 + reacts with isotatic polypropylene (iPP, M n = 13.3 kDa; Đ = 2.4; mmmm = 94%; ∼110 C 3 H 6 /Hf) and H 2 to form oils with moderate molecular weights ( M n = 290-1200 Da) in good yields. The aliphatic oils show characteristic 13 C{ 1 H} NMR properties consistent with complete loss of diastereoselectivity and formation of regioirregular errors under 1 atm H 2 . These results show that a Ziegler-Natta-type active site is compatible in a common reaction used to digest waste plastic into smaller aliphatic fragments.

Well-defined organometallics supported on high surface area oxides are promising heterogeneous catalysts. An important design factor in these materials is how the metal interacts with the functionalities on an oxide support, commonly anionic X-type ligands derived from the reaction of an organometallic M-R with an -OH site on the oxide. The metal can either form a covalent M-O bond or form an electrostatic M + ⋯ - O ion-pair, which impacts how well-defined organometallics will interact with substrates in catalytic reactions. A less common reaction pathway involves the reaction of a Lewis site on the oxide with the organometallic, resulting in abstraction to form an ion-pair, which is relevant to industrial olefin polymerization catalysts. This Feature Article views the spectrum of reactivity between an organometallic and an oxide through the prism of Brønsted and/or Lewis acidity of surface sites and draws analogies to the molecular frame where Lewis and Brønsted acids are known to form reactive ion-pairs. Applications of the well-defined sites developed in this article are also discussed.

Sulfated aluminum oxide ( SAO ), a high surface area material containing sulfate anions that behave like weakly coordinating anions, reacts with Ta(═CH t Bu)(CH 2 t Bu) 3 to form [Ta(CH 2 t Bu) 2 (O-) 2 ][ SAO ] ( 1 ). Subsequent treatment with H 2 forms Ta-H + sites supported on SAO that are active in hydrogenolysis and alkane metathesis reactions. In both reactions Ta-H + is more active than related neutral Ta-H sites supported on silica. This reaction chemistry extends to melts of high-density polyethylene (HDPE), where Ta-H + converts 30% of a low molecular weight HDPE ( M n = 2.5 kg mol -1 ; Đ = 3.6) to low molecular weight paraffins under hydrogenolysis conditions. Under alkane metathesis conditions Ta-H + converts this HDPE to a high MW fraction ( M n = 6.2 kDa; Đ = 2.3) and low molecular weight alkane products (C 13 -C 32 ). These results show that incorporating charge as a design element in supported d 0 metal hydrides is a viable strategy to increase the reaction rate in challenging reactions involving reorganization of C-C bonds in alkanes.

Despite decreases in US opioid prescribing rates, daily morphine milligram equivalents (MME) prescribed per person remains three times higher than in 1999. An interprofessional team (IPT) was developed to support pain management for patients prescribed long-term high-dose opioids (HDO) in a Federally Qualified Health Center. The IPT utilized a clinical pharmacist, addiction nurse, medical director, and another physician or nurse practitioner to manage adults prescribed long-term HDO, defined as exceeding 50 daily MME. Visits focused on patient education including risks associated with long-term HDO use and effective pain management. The IPT engaged in supportive, individualized care planning for safer, evidence-based pain management, which included, but was not limited to opioid tapers, adjuvant non-opioid pain medications (NOPM), non-pharmacological therapy (NPT), and naloxone co-prescribing. The IPT saw 90% (n = 19) of eligible patients. Excluding outliers, the cohort demonstrated an average 18% ± 24.9 decrease in daily MME. The most common NOPM were acetaminophen, NSAIDs, and pregabalin, and the most common NPT were physical, aquatic, and behavioral therapy. Shared decision-making, collaborative teamwork, and simple patient-centered goals are key to moving patients toward safer, evidence-based therapy.

The reaction of W(NAr)( 13 C 4 H 8 )(OSiPh 3 ) 2 ( 1 ) (NAr = 2,6-diisopropylphenylimido) with silica partially dehydroxylated at 700 °C (SiO 2-700 ) is highly dependent on the reaction conditions. The primary product of this reaction is W(NAr)( 13 C 4 H 8 )(OSiPh 3 )(OSi(O-) 3 ) ( 2 ) when the reaction is carried out in the dark. Grafting 1 onto SiO 2-700 in ambient lab light results in the formation of 2 , W(NAr)( 13 CH 2 13 CH 2 )(OSiPh 3 )(OSi(O-) 3 ) ( 4 ), and one isomer of square-pyramidal W(NAr)( 13 CH 2 13 CH( 13 Me) 13 CH 2 )(OSiPh 3 )(OSi(O-) 3 ) ( 3 ). Heating 2 to 85 °C for 6 h results in the formation of 3 , 4 , W(NAr)( 13 CH( 13 Me) 13 CH 2 13 CH 2 )(OSiPh 3 )(OSi(O-) 3 ) ( 5 ), and W(NAr)(( 13 CH 2 ) 2 13 CH( 13 Me)( 13 CH 2 ) 2 )(OSiPh 3 )(OSi(O-) 3 ) ( 6 ). Photolysis of 2 with blue LEDs (λ max = 450 nm) produces 4, both isomers of 3, 5 , and free ethylene. In the presence of excess ethylene and blue LED irradiation at 85 °C, 1 /SiO 2-700 catalyzes the direct conversion of ethylene to propylene.

Al(OC(CF 3 ) 3 )(PhF) reacts with silanols present on partially dehydroxylated silica to form well-defined ≡SiOAl(OC(CF 3 ) 3 ) 2 (O(Si≡) 2 ) (1). 27 Al NMR and DFT calculations with a small cluster model to approximate the silica surface show that the aluminum in 1 adopts a distorted trigonal bipyramidal coordination geometry by coordinating to a nearby siloxane bridge and a fluorine from the alkoxide. Fluoride ion affinity (FIA) calculations follow experimental trends and show that 1 is a stronger Lewis acid than B(C 6 F 5 ) 3 and Al(OC(CF 3 ) 3 )(PhF) but is weaker than Al(OC(CF 3 ) 3 ) and i Pr 3 Si + . Cp 2 Zr(CH 3 ) 2 reacts with 1 to form [Cp 2 ZrCH 3 ][≡SiOAl(OC(CF 3 ) 3 ) 2 (CH 3 )] (3) by methide abstraction. This reactivity pattern is similar to reactions of organometallics with the proposed strong Lewis acid sites present on Al 2 O 3 ., (© 2022 Wiley-VCH GmbH.)

Sulfated zirconium oxide (SZO) capped with silylium-like ions reacts with (cod)Ir(py)Cl (cod = 1,5-cyclooctadiene; py = pyridine) to form [Ir(cod)py][SZO] ( 1 ) and Me 3 SiCl. 1 can also be formed in reactions of phosphonium functionalized SZO and [Ir(cod)(OSi(O t Bu) 3 ] 2 , which forms [Ir(cod)P( t Bu) 2 Ph][SZO] ( 2 ), followed by reaction with pyridine to form 1 . FTIR and 15 N{ 1 H} MAS NMR spectroscopy are consistent with coordination of pyridine in 1 to an electrophilic iridium. 1 is moderately active in the dearomative hydroboration of pyridine. The primary product of this reaction is 1,2-dihydropyridine, which converts to the 1,4-dihydropyridine product at long reaction times. 1 catalyzes the dearomative hydroboration of a variety of substituted pyridines and is also reactive toward pyrazines and N -methylimidazole.

Exposure of a solution of the square pyramidal tungstacyclopentane complex W(NAr)(OSiPh 3 ) 2 (C 4 H 8 ) (Ar = 2,6- i -Pr 2 C 6 H 3 ) to ethylene at 22 °C in ambient (fluorescent) light slowly leads to the formation of propylene and the square pyramidal tungstacyclobutane complex W(NAr)(OSiPh 3 ) 2 (C 3 H 6 ). No reaction takes place in the dark, but the reaction is >90% complete in ∼15 min under blue LED light (∼450 nm λ max ). The intermediates are proposed to be (first) an α methyl tungstacyclobutane complex (W(NAr)(OSiPh 3 ) 2 (αMeC 3 H 5 )), and then from it, a β methyl version. The TBP versions of each can lose propylene and form a methylene complex, and in the presence of ethylene, the unsubstituted tungstacyclobutane complex W(NAr)(OSiPh 3 ) 2 (C 3 H 6 ). The W-C α bond in an unobservable TBP W(NAr)(OSiPh 3 ) 2 (C 4 H 8 ) isomer in which the C 4 H 8 ring is equatorial is proposed to be cleaved homolytically by light. A hydrogen atom moves or is moved from C3 to the terminal C4 carbon in the butyl chain as the bond between W and C3 forms to give the TBP α methyl tungstacyclobutane complex. Essentially, the same behavior is observed for W(NCPh 3 )(OSiPh 3 ) 2 (C 4 H 8 ) as for W(NAr)(OSiPh 3 ) 2 (C 4 H 8 ), except that the rate of consumption of W(NCPh 3 )(OSiPh 3 ) 2 (C 4 H 8 ) is about half that of W(NAr)(OSiPh 3 ) 2 (C 4 H 8 ). In this case, an α methyl-substituted tungstacyclobutane intermediate is observed, and the overall rate of formation of W(NCPh 3 )(OSiPh 3 ) 2 (C 3 H 6 ) and propylene from W(NCPh 3 )(OSiPh 3 ) 2 (C 4 H 8 ) is ∼20 times slower than in the NAr system. These results constitute the first experimentally documented examples of forming a metallacyclobutane ring from a metallacyclopentane ring (ring contraction) and establish how metathesis-active methylene and metallacyclobutane complexes can be formed and reformed in the presence of ethylene. They also raise the possibility that ambient light could play a role in some metathesis reactions that involve ethylene and tungsten-based imido alkylidene olefin metathesis catalysts, if not others.

Understanding how a ligand affects the steric and electronic properties of a metal is the cornerstone of the inorganic chemistry enterprise. What happens when the ligand is an extended surface? This question is central to the design and implementation of state-of-the-art functional materials containing transition metals. This perspective will describe how these two very different sets of extended surfaces can form well-defined coordination complexes with metals. In the Green formalism, functionalities on oxide surfaces react with inorganics to form species that contain X-type or LX-type interactions between the metal and the oxide. Carbon surfaces are neutral L-type ligands; this perspective focuses on carbons that donate six electrons to a metal. The nature of this interaction depends on the curvature, and thereby orbital overlap, between the metal and the extended π-system from the nanocarbon.

The silylium-like surface species [ i Pr 3 Si][(R F O) 3 Al-OSi≡)] activates (N^N)Pd(CH 3 )Cl (N^N=Ar-N=CMeMeC=N-Ar, Ar=2,6-bis(diphenylmethyl)-4-methylbenzene) by chloride ion abstraction to form [(N^N)Pd-CH 3 ][(R F O) 3 Al-OSi≡)] (1). A combination of FTIR, solid-state NMR spectroscopy, and reactions with CO or vinyl chloride establish that 1 shows similar reactivity patterns as (N^N)Pd(CH 3 )Cl activated with Na[B(Ar F ) 4 ]. Multinuclear 13 C{ 27 Al} RESPDOR and 1 H{ 19 F} S-REDOR experiments are consistent with a weakly coordinated ion-pair between (N^N)Pd-CH 3 + and [(R F O) 3 Al-OSi≡)]. 1 catalyzes the polymerization of ethylene with similar activities as [(N^N)Pd-CH 3 ] + in solution and incorporates up to 0.4 % methyl acrylate in copolymerization reactions. 1 produces polymers with significantly higher molecular weight than the solution catalyst, and generates the highest molecular weight polymers currently reported in copolymerization reactions of ethylene and methylacrylate., (© 2022 Wiley-VCH GmbH.)

Transition metal interactions with Lewis acids (M → Z linkages) are fundamentally interesting and practically important. The most common Z-type ligands contain boron, which contains an NMR active 11 B nucleus. We measured solid-state 11 B{ 1 H} NMR spectra of copper, silver, and gold complexes containing a phosphine substituted 9,10-diboraanthracene ligand (B 2 P 2 ) that contain planar boron centers and weak M → BR 3 linkages ([(B 2 P 2 )M][BAr F 4 ] (M = Cu (1), Ag (2), Au (3)) characterized by large quadrupolar coupling ( C Q ) values (4.4-4.7 MHz) and large span ( Ω ) values (93-139 ppm). However, the solid-state 11 B{ 1 H} NMR spectrum of K[Au(B 2 P 2 )] - (4), which contains tetrahedral borons, is narrow and characterized by small C Q and Ω values. DFT analysis of 1-4 shows that C Q and Ω are expected to be large for planar boron environments and small for tetrahedral boron, and that the presence of a M → BR 3 linkage relates to the reduction in C Q and 11 B NMR shielding properties. Thus solid-state 11 B NMR spectroscopy contains valuable information about M → BR 3 linkages in complexes containing the B 2 P 2 ligand.

Upon addition of 5-15% PhNMe 2 H + X - (X = B(3,5-(CF 3 ) 2 C 6 H 3 ) 4 or B(C 6 F 5 ) 4 ) to Mo(NAr)(styrene)(OSiPh 3 ) 2 (Ar = N-2,6- i -Pr 2 C 6 H 3 ) in C 6 D 6 an equilibrium mixture of Mo(NAr)(styrene)(OSiPh 3 ) 2 and Mo(NAr)(CMePh)(OSiPh 3 ) 2 is formed over 36 h at 45 °C ( K eq = 0.36). A plausible intermediate in the interconversion of the styrene and 1-phenethylidene complexes is the 1-phenethyl cation, [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 ] + , which can be generated using [(Et 2 O) 2 H][B(C 6 F 5 ) 4 ] as the acid. The interconversion can be modeled as two equilibria involving protonation of Mo(NAr)(styrene)(OSiPh 3 ) 2 or Mo(NAr)(CMePh)(OSiPh 3 ) 2 and deprotonation of the α or β phenethyl carbon atom in [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 ] + . The ratio of the rate of deprotonation of [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 ] + by PhNMe 2 in the α position versus the β position is ∼10, or ∼30 per H β . The slow step is protonation of Mo(NAr)(styrene)(OSiPh 3 ) 2 ( k 1 = 0.158(4) L/(mol·min)). Proton sources such as (CF 3 ) 3 COH or Ph 3 SiOH do not catalyze the interconversion of Mo(NAr)(styrene)(OSiPh 3 ) 2 and Mo(NAr)(CMePh)(OSiPh 3 ) 2 , while the reaction of Mo(NAr)(styrene)(OSiPh 3 ) 2 with pyridinium salts generates only a trace (∼2%) of Mo(NAr)(CMePh)(OSiPh 3 ) 2 and forms a monopyridine adduct, [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 (py)] + (two diastereomers). The structure of [Mo(NAr)(CHMePh)(OSiPh 3 ) 2 ] + has been confirmed in an X-ray study; there is no structural indication that a β proton is activated through a CH β interaction with the metal. W(NAr)(CMePh)(OSiPh 3 ) 2 is also converted into a mixture of W(NAr)(CMePh)(OSiPh 3 ) 2 and W(NAr)(styrene)(OSiPh 3 ) 2 ( K eq = 0.47 at 45 °C in favor of the styrene complex) with 10% [PhNMe 2 H][B(C 6 F 5 ) 4 ] as the catalyst; the time required to reach equilibrium is approximately the same as in the Mo system.

Heterogeneous derivatives of catalysts discovered by Ziegler and Natta are important for the industrial production of polyolefin plastics. However, the interaction between precatalysts, alkylaluminum activators, and oxide supports to form catalytically active materials is poorly understood. This is in contrast to homogeneous or model heterogeneous catalysts that contain resolved molecular structures that relate to activity and selectivity in polymerization reactions. This study describes the reactivity of triisobutylaluminum with high surface area aluminum oxide and a zirconocene precatalyst. Triisobutylaluminum reacts with the zirconocene precatalyst to form hydrides and passivates -OH sites on the alumina surface. The combination of passivated alumina and zirconium hydrides formed in this mixture generates ion pairs that polymerize ethylene., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

PAr 3 containing o -OMe, o -Me, or o -Et substituents reacts with Brønsted sites on sulfated zirconium oxide ( SZO ) to form [HPAr 3 ][ SZO ]. The phosphonium sites on this material react with bis(cyclooctadiene)nickel [Ni(cod) 2 ] to form [Ni(PAr 3 )(codH)][ SZO ] that are active in ethylene polymerization reactions. Selective poisoning studies with pyridine show that ∼90% of the Ni(PAr 3 )(codH) + sites in this material are active in polymerization reactions.

The origin in deshielding of 29Si NMR chemical shifts in R3Si-X, where X = H, OMe, Cl, OTf, [CH6B11X6], toluene, and OX (OX = surface oxygen), as well as iPr3Si+ and Mes3Si+ were studied using DFT methods. At the M06-L/6-31G(d,p) level of theory the geometry optimized structures agree well with those obtained experimentally. The trends in 29Si NMR chemical shift also reproduce experimental trends; iPr3Si-H has the most shielded 29Si NMR chemical shift and free iPr3Si+ or isolable Mes3Si+ have the most deshielded 29Si NMR chemical shift. Natural localized molecular orbital (NLMO) analysis of the contributions to paramagnetic shielding (σp) in these compounds shows that Si-R (R = alkyl, H) bonding orbitals are the major contributors to deshielding in this series. The Si-R bonding orbitals are coupled to the empty p-orbital in iPr3Si+ or Mes3Si+, or to the orbital in R3Si-X. This trend also applies to surface bound R3Si-OX. This model also explains chemical shift trends in recently isolated tBu2SiH2+, tBuSiH2+, and SiH3+ that show more shielded 29Si NMR signals than R3Si+ species. There is no correlation between isotropic 29Si NMR chemical shift and charge at silicon.

Objective: Glucagon-like peptide-1 (GLP-1) receptor agonists are preferred injectable therapies for type 2 diabetes, but their high cost is an area of concern. This study evaluated monthly glucose-lowering medication cost and clinical impact after initiating a GLP-1 receptor agonist., Design: A retrospective, pre-post cohort study evaluated monthly glucose-lowering medication cost, glycated hemoglobin (HbA 1c ), weight, and polytherapy impact (name, dose, and number of daily doses or injections) when a GLP-1 receptor agonist was initiated (baseline) and after 6-12 months (follow-up). The population was analyzed overall and as subgroups, based on baseline medication regimen and demographics., Setting and Participants: The study was performed at 8 ambulatory care sites (7 federally qualified health centers and a Program of All-Inclusive Care for the Elderly) in the greater Boston, MA, area. Patients were included in the analyses (n = 120) if they had a documented diagnosis of type 2 diabetes, were 18 years of age or older, had an HbA 1c ≥ 7.5% measured within 3 months prior to the initiation of a GLP-1 receptor agonist, and an HbA 1c measured 6 to 12 months following the initiation of a GLP-1 receptor agonist., Outcome Measures: Primary outomes were changes in glucose-lowering medication cost, HbA 1c , and weight. Secondary outcome analyses included the impact to the glucose-lowering medication regimen in terms of dose, number of medications, and number of daily doses or injections., Results: The study population was largely female, aged 55.8 ± 11.7 years, obese, 76% non-Caucasian, equally English and non-English speaking, had a high tablet and injection burden, and had an average baseline HbA 1c of 10%. After the addition of a GLP-1 receptor agonist, monthly glucose-lowering medication cost increased $586.86 (overall), $741.69 (oral only baseline regimen), and $530.55 (insulin ± oral baseline regimen) (all P < 0.001). Mean decrease in HbA 1c was 1.7% (18 mmol/mol) (P < 0.001) and was similar across all subgroups. Weight decreased overall (-1.8 kg, P < 0.001), and there was a significant shift toward taking fewer oral agents and insulin and fewer daily injections. No statistically significant differences in the primary outcomes were noted in terms of age, gender, English-speaking status, or race., Conclusion: Although a positive impact was observed in glycemic control, weight, and reduced polytherapy 6-12 months after initiating a GLP-1 receptor agonist, the increase in monthly glucose-lowering medication cost was significant and may serve as a barrier to treatment., (Copyright © 2020 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Weakly Coordinating Anions (WCAs) containing electron deficient delocalized anionic fragments that are reasonably inert allow for the isolation of strong electrophiles. Perfluorinated borates, perfluorinated aluminum alkoxides, and halogenated carborane anions are a few families of WCAs that are commonly used in synthesis. Application of similar design strategies to oxide surfaces is challenging. This paper describes the reaction of Al(OR F ) 3 *PhF (R F = C(CF 3 ) 3 ) with silica partially dehydroxylated at 700 °C (SiO 2-700 ) to form the bridging silanol [triple bond, length as m-dash]Si-OH⋯Al(OR F ) 3 ( 1 ). DFT calculations using small clusters to model 1 show that the gas phase acidity (GPA) of the bridging silanol is 43.2 kcal mol -1 lower than the GPA of H 2 SO 4 , but higher than the strongest carborane acids, suggesting that deprotonated 1 would be a WCA. Reactions of 1 with NOct 3 show that 1 forms weaker ion-pairs than classical WCAs, but stronger ion-pairs than carborane or borate anions. Though 1 forms stronger ion-pairs than these state-of-the-art WCAs, 1 reacts with alkylsilanes to form silylium type surface species. To the best of our knowledge, this is the first example of a silylium supported on derivatized silica., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Here we apply microcrystal electron diffraction (MicroED) to the structural determination of transition-metal complexes. We find that the simultaneous use of 300 keV electrons, very low electron doses, and an ultrasensitive camera allows for the collection of data without cryogenic cooling of the stage. This technique reveals the first crystal structures of the classic zirconocene hydride, colloquially known as "Schwartz's reagent", a novel Pd(II) complex not amenable to solution-state NMR or X-ray crystallography, and five other paramagnetic and diamagnetic transition-metal complexes., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)

The reaction of ( t Bu) 2 ArP (1a-h), where the para position of the Ar group contains electron-donating or electron-withdrawing groups, with sulfated zirconium oxide partially dehydroxylated at 300 °C (SZO 300 ) forms [( t Bu) 2 ArPH][SZO 300 ] (2a-h). The equilibrium binding constants of 1a-h to SZO 300 are related to the p K a of [( t Bu) 2 ArPH]; R 3 P that form less acidic phosphoniums (high p K a values) bind stronger to SZO 300 than R 3 P that form more acidic phosphoniums (low p K a values). These studies show that Brønsted acid sites on the surface of SZO 300 are not superacidic.

C-H bond activation via σ-bond metathesis is typically observed with transition-metal alkyl compounds in d 0 or d 0 f n electron configurations, e.g., biscyclopentadienyl metal alkyls. Related C-H activation processes are also observed for transition-metal alkyls with higher d-electron counts, such as W(II), Fe(II), or Ir(III). A σ-bond metathesis mechanism has been proposed in all cases with a preference for an oxidative addition-reductive elimination pathway for Ir(III). Herein we show that, regardless of the exact mechanism, C-H activation with all of these compounds is associated with π-character of the M-C bond, according to a detailed analysis of the 13 C NMR chemical shift tensor of the α-carbon. π-Character is also a requirement for olefin insertion, indicating its similarity to σ-bond metathesis. This observation explains the H 2 response observed in d 0 olefin polymerization catalysts and underlines that σ-bond metathesis, olefin insertion, and olefin metathesis are in fact isolobal reactions.

The reaction of allyltriisopropylsilane with partially dehydroxylated sulfated zirconium oxide (SZO) forms surface organosilicon species. Solid-state NMR studies of the organosilicon functionalized SZO shows that electrophilic [TIPS][SZO] sites are present on the surface, in addition to less reactive TIPS-O x and SiO x species. The electrophilic [TIPS][SZO] sites are strong Lewis acids from solid-state 31 P NMR analysis of triethylphosphine oxide (O=PEt 3 ) contacted materials. [TIPS][SZO] is active in hydrodefluorination reactions in the presence of Et 3 SiH., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Cp* 2 Sc-X, where X is a halide, were synthesized and studied by solid-state 45 Sc NMR to determine how the Sc-X bond affects quadrupolar NMR parameters. The experimental quadrupolar coupling constants (C Q ) show that the fluoride has the largest coupling constant and that the iodide has the smallest coupling constant. DFT analysis of this data indicates that the C Q of these compounds is related to core scandium and halide orbitals, which is related to polarizability of the halide and the Sc-X distance. Cp* 2 ScX(THF) were also investigated by solid-state 45 Sc NMR spectroscopy, and have much smaller C Q values than the base-free halides. This is related to the change in structure of the THF adduct and occupation of orbitals of π-symmetry that reduce C Q .

Objective. To implement and assess the curricular integration of the Pharmacists' Patient Care Process (PPCP) in a course series for second- and third-year pharmacy students. Methods. The five-step PPCP was integrated within a four-semester pharmacotherapy course starting with the introductory course lectures. Beginning in the spring of 2015, the five steps of the PPCP were delivered to 129 P2 students, along with rollout of curricular integration within corresponding classroom and seminar activities and assessments. Integration focused on the development of course-specific lecture and seminar materials, a faculty guidance strategy and templates, and evaluation approaches for course assessments. Student comprehension and utilization of the PPCP were assessed via 61 unique assessments (12 examinations and 49 quizzes). Faculty incorporation and perception of the PPCP were evaluated via survey. Results. Overall, students demonstrated the most understanding on the lowest levels of the PPCP: 83.6% and 82.2% for the Collect and Implement components, respectively, compared to the higher-level components of Planning (78.0%) and Follow-up (76.0%). Faculty understanding, integration, and utilization of the PPCP in course materials were assessed approximately 6 months after implementation. Twenty-two faculty (96% of course instructors) participated in the survey. Eighteen (82%) have modified instructional materials to incorporate PPCP and among these, 89% agreed/strongly agreed that they possessed a clear understanding of the PPCP. Conclusion. Implementing a successful curricular change such as the integration of the PPCP across multiple courses requires a multi-faceted approach. The development of faculty templates and provision of support through various methods are necessary to ensure consistent and comprehensive integration across the curriculum. Additionally, evaluation of student performance and achievement of intended outcomes should be used to guide curricular assessments and continuous quality improvements throughout the process.

Multinuclear solid-state NMR studies of Cp* 2 Sc-R (Cp*=pentamethylcyclopentadienyl; R=Me, Ph, Et) and DFT calculations show that the Sc-Et complex contains a β-CH agostic interaction. The static central transition 45 Sc NMR spectra show that the quadrupolar coupling constants (C q ) follow the trend of Ph≈Me>Et, indicating that the Sc-R bond is different in Cp* 2 Sc-Et compared to the methyl and phenyl complexes. Analysis of the chemical shift tensor (CST) shows that the deshielding experienced by Cβ in Sc-CH 2 CH 3 is related to coupling between the filled σ C-C orbital and the vacant πSc⋯HC* orbital., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Many industrial catalysts contain isolated metal sites on the surface of oxide supports. Although such catalysts have been used in a broad range of processes for more than 40 years, there is often a very limited understanding about the structure of the catalytically active sites. This Review discusses how surface organometallic chemistry (SOMC) engineers surface sites with well-defined structures and provides insight into the nature of the active sites of industrial catalysts; the Review focuses in particular on olefin production and conversion processes., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The spatial arrangement of atoms is directly linked to chemical function. A fundamental challenge in surface chemistry and catalysis relates to the determination of three-dimensional structures with atomic-level precision. Here we determine the three-dimensional structure of an organometallic complex on an amorphous silica surface using solid-state NMR measurements, enabled through a dynamic nuclear polarization surface enhanced NMR spectroscopy approach that induces a 200-fold increase in the NMR sensitivity for the surface species. The result, in combination with EXAFS, is a detailed structure for the surface complex determined with a precision of 0.7 Å. We observe a single well-defined conformation that is folded toward the surface in such a way as to include an interaction between the platinum metal center and the surface oxygen atoms.

Re2O7 supported on γ-alumina is an alkene metathesis catalyst active at room temperature, compatible with functional groups, but the exact structures of the active sites are unknown. Using CH3ReO3/Al2O3 as a model for Re2O7/Al2O3, we show through a combination of reactivity studies, in situ solid-state NMR, and an extensive series of DFT calculations, that μ-methylene structures (Al-CH2-ReO3-Al) containing a Re═O bound to a tricoordinated Al (AlIII) and CH2 bound to a four-coordinated Al (AlIVb) are the precursors of the most active sites for olefin metathesis. The resting state of CH3ReO3/Al2O3 is a distribution of μ-methylene species formed by the activation of the C-H bond of CH3ReO3 on different surface Al-O sites. In situ reaction with ethylene results in the formation of Re metallacycle intermediates, which were studied in detail through a combination of solid-state NMR experiments, using labeled ethylene, and DFT calculations. In particular, we were able to distinguish between metallacycles in TBP (trigonal-bipyramidal) and SP (square-pyramidal) geometry, the latter being inactive and detrimental to catalytic activity. The SP sites are more likely to be formed on other Al sites (AlIVa/AlIVa). Experimentally, the activity of CH3ReO3/Al2O3 depends on the activation temperature of alumina; catalysts activated at or above 500 °C contain more active sites than those activated at 300 °C. We show that the dependence of catalytic activity on the Al2O3 activation temperature is related to the quantity of available AlIII-defect sites and adsorbed H2O.

Lu[CH(SiMe3)2]3 reacts with [SiO2-700] to give [(≡SiO)Lu[CH(SiMe3)2]2] and CH2(SiMe3)2. [(≡SiO)Lu[CH(SiMe3)2]2] is characterized by solid-state NMR and EXAFS spectroscopy, which show that secondary Lu···C and Lu···O interactions, involving a γ-CH3 and a siloxane bridge, are present. From X-ray crystallographic analysis, the molecular analogues Lu[CH(SiMe3)2]3-x[O-2,6-tBu-C6H3]x (x = 0-2) also have secondary Lu···C interactions. The (1)H NMR spectrum of Lu[CH(SiMe3)2]3 shows that the -SiMe3 groups are equivalent to -125 °C and inequivalent below that temperature, ΔG(⧧)(Tc = 148 K) = 7.1 kcal mol(-1). Both -SiMe3 groups in Lu[CH(SiMe3)2]3 have (1)JCH = 117 ± 1 Hz at -140 °C. The solid-state (13)C CPMAS NMR spectrum at 20 °C shows three chemically inequivalent resonances in the area ratio of 4:1:1 (12:3:3); the J-resolved spectra for each resonance give (1)JCH = 117 ± 2 Hz. The (29)Si CPMAS NMR spectrum shows two chemically inequivalent resonances with different values of chemical shift anisotropy. Similar observations are obtained for Lu[CH(SiMe3)2]3-x[O-2,6-tBu-C6H3]x (x = 1 and 2). The spectroscopic data point to short Lu···Cγ contacts corresponding to 3c-2e Lu···Cγ-Siβ interactions, which are supported by DFT calculations. Calculated natural bond orbital (NBO) charges show that Cγ carries a negative charge, while Lu, Hγ, and Siβ carry positive charges; as the number of O-based ligands increases so does the positive charge at Lu, which in turns shortens the Lu···Cγ distance. The change in NBO charges and the resulting changes in the spectroscopic and crystallographic properties show how ligands and surface-support sites rearrange to accommodate these changes, consistent with Pauling's electroneutrality concept.

We describe the reactivity of well-defined chromium silicates toward ethylene and propane. The initial motivation for this study was to obtain a molecular understanding of the Phillips polymerization catalyst. The Phillips catalyst contains reduced chromium sites on silica and catalyzes the polymerization of ethylene without activators or a preformed Cr-C bond. Cr(II) sites are commonly proposed active sites in this catalyst. We synthesized and characterized well-defined chromium(II) silicates and found that these materials, slightly contaminated with a minor amount of Cr(III) sites, have poor polymerization activity and few active sites. In contrast, chromium(III) silicates have 1 order of magnitude higher activity. The chromium(III) silicates initiate polymerization by the activation of a C-H bond of ethylene. Density functional theory analysis of this process showed that the C-H bond activation step is heterolytic and corresponds to a σ-bond metathesis type process. The same well-defined chromium(III) silicate catalyzes the dehydrogenation of propane at elevated temperatures with activities similar to those of a related industrial chromium-based catalyst. This reaction also involves a key heterolytic C-H bond activation step similar to that described for ethylene but with a significantly higher energy barrier. The higher energy barrier is consistent with the higher pKa of the C-H bond in propane compared to the C-H bond in ethylene. In both cases, the rate-determining step is the heterolytic C-H bond activation.

The reaction of [W(=O)(=CHCMe2Ph)(dAdPO)2], containing bulky 2,6-diadamantyl aryloxide ligands, with partially dehydroxylated silica selectively yields a well-defined silica-supported alkylidene complex, [(≡SiO)W(=O)(=CHCMe2Ph)(dAdPO)]. This fully characterized material is a very active and stable alkene metathesis catalyst, thus allowing loadings as low as 50 ppm in the metathesis of internal alkenes. [(≡SiO)W(=O)(=CHCMe2Ph)(dAdPO)] also efficiently catalyzes the homocoupling of terminal alkenes, with turnover numbers exceeding 75,000 when ethylene is constantly removed to avoid the formation of the less reactive square-based pyramidal metallacycle resting state., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hyperpolarization of substrates for magnetic resonance spectroscopy (MRS) and imaging (MRI) by dissolution dynamic nuclear polarization (D-DNP) usually involves saturating the ESR transitions of polarizing agents (PAs; e.g., persistent radicals embedded in frozen glassy matrices). This approach has shown enormous potential to achieve greatly enhanced nuclear spin polarization, but the presence of PAs and/or glassing agents in the sample after dissolution can raise concerns for in vivo MRI applications, such as perturbing molecular interactions, and may induce the erosion of hyperpolarization in spectroscopy and MRI. We show that D-DNP can be performed efficiently with hybrid polarizing solids (HYPSOs) with 2,2,6,6-tetramethyl-piperidine-1-oxyl radicals incorporated in a mesostructured silica material and homogeneously distributed along its pore channels. The powder is wetted with a solution containing molecules of interest (for example, metabolites for MRS or MRI) to fill the pore channels (incipient wetness impregnation), and DNP is performed at low temperatures in a very efficient manner. This approach allows high polarization without the need for glass-forming agents and is applicable to a broad range of substrates, including peptides and metabolites. During dissolution, HYPSO is physically retained by simple filtration in the cryostat of the DNP polarizer, and a pure hyperpolarized solution is collected within a few seconds. The resulting solution contains the pure substrate, is free from any paramagnetic or other pollutants, and is ready for in vivo infusion.

Grafting reactive molecular complexes on dehydroxylated amorphous silica is a strategy to develop "single-site" heterogeneous catalysts. In general, only the reactivity of isolated silanols is invoked for silica dehydroxylated at 700 °C ([SiO(2-700)]), though ca. 10% of the surface silanols are in fact geminal Q2-silanols. Here we report the reaction of allyltributylstannane with [SiO(2-700)] and find that the geminal Q2-silanols react to form products that would formally arise from vicinal Q3-silanols that are not present on [SiO(2-700)], indicating that a surface rearrangement occurs. The reorganization of the silica surface is unique to silica dehydroxylated at 700 °C or above. The findings were identified using Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) combined with DFT calculations.

Mononuclear Cr(III) surface sites were synthesized from grafting [Cr(OSi(O(t)Bu)3)3(tetrahydrofurano)2] on silica partially dehydroxylated at 700 °C, followed by a thermal treatment under vacuum, and characterized by infrared, ultraviolet-visible, electron paramagnetic resonance (EPR), and X-ray absorption spectroscopy (XAS). These sites are highly active in ethylene polymerization to yield polyethylene with a broad molecular weight distribution, similar to that typically obtained from the Phillips catalyst. CO binding, EPR spectroscopy, and poisoning studies indicate that two different types of Cr(III) sites are present on the surface, one of which is active in polymerization. Density functional theory (DFT) calculations using cluster models show that active sites are tricoordinated Cr(III) centers and that the presence of an additional siloxane bridge coordinated to Cr leads to inactive species. From IR spectroscopy and DFT calculations, these tricoordinated Cr(III) sites initiate and regulate the polymer chain length via unique proton transfer steps in polymerization catalysis.

The prevalence of diabetes in the United States is increasing and so is the need to provide diabetes care. Given the time commitment and complexity of diabetes management, an interdisciplinary approach is recommended. Pharmacists are integral members of the diabetes care team because of their accessibility and expertise in medication management. Pharmacists are receiving specialized training and becoming more involved in direct patient care through collaborative practice opportunities such as medication therapy management and collaborative drug therapy management. These collaborative practice models increase patient access to care and allow pharmacists to optimize drug therapy and provide important education to promote diabetes self-management. Studies show pharmacists practicing in a variety of outpatient environments can reduce HbA1c, LDL and BP as well as improve adherence to recommended American Diabetes Association guidelines (yearly monofilament exams, dilated eye exams, microalbumin screening, etc). Pharmacists working as part of the health care team can ensure optimal diabetes management.

The insertion of an olefin into a preformed metal-carbon bond is a common mechanism for transition-metal-catalyzed olefin polymerization. However, in one important industrial catalyst, the Phillips catalyst, a metal-carbon bond is not present in the precatalyst. The Phillips catalyst, CrO3 dispersed on silica, polymerizes ethylene without an activator. Despite 60 years of intensive research, the active sites and the way the first CrC bond is formed remain unknown. We synthesized well-defined dinuclear Cr(II) and Cr(III) sites on silica. Whereas the Cr(II) material was a poor polymerization catalyst, the Cr(III) material was active. Poisoning studies showed that about 65 % of the Cr(III) sites were active, a far higher proportion than typically observed for the Phillips catalyst. Examination of the spent catalyst and isotope labeling experiments showed the formation of a Si-(μ-OH)-Cr(III) species, consistent with an initiation mechanism involving the heterolytic activation of ethylene at Cr(III) O bonds., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Grafting (ArO)2W(═O)(═CHtBu) (ArO = 2,6-mesitylphenoxide) on partially dehydroxylated silica forms mostly [(≡SiO)W(═O)(═CHtBu)(OAr)] along with minor amounts of [(≡SiO)W(═O)(CH2tBu)(OAr)2] (20%), both fully characterized by elemental analysis and IR and NMR spectroscopies. The well-defined oxo alkylidene surface complex [(≡SiO)W(═O)(═CHtBu)OAr] is among the most active heterogeneous metathesis catalysts reported to date in the self-metathesis of cis-4-nonene and ethyl oleate, in sharp contrast to the classical heterogeneous catalysts based on WO3/SiO2.

Mesoporous hybrid silica-organic materials containing homogeneously distributed stable mono- or dinitroxide radicals covalently bound to the silica surface were developed as polarization matrixes for solid-state dynamic nuclear polarization (DNP) NMR experiments. For TEMPO-containing materials impregnated with water or 1,1,2,2-tetrachloroethane, enhancement factors of up to 36 were obtained at ∼100 K and 9.4 T without the need for a glass-forming additive. We show that the homogeneous radical distribution and the subtle balance between the concentration of radical in the material and the fraction of radicals at a sufficient inter-radical distance to promote the cross-effect are the main determinants for the DNP enhancements we obtain. The material, as well as an analogue containing the poorly soluble biradical bTUrea, is used as a polarizing matrix for DNP NMR experiments of solutions containing alanine and pyruvic acid. The analyte is separated from the polarization matrix by simple filtration.

Triisobutylaluminum reacts with silica yielding three different Al sites according to high-field aluminum-27 NMR and first principle calculations: a quadruply grafted dimeric surface species and two incorporated Al(O)x species (x = 4 or 5). This result is in stark contrast to the bis-grafted species that forms during Et3Al silica grafting. Thus the isobutyl ligands, which render R3Al monomeric, lead to greater reactivity towards the silica surface.

Direct evidence of the conformation of a Pd-N heterocyclic carbene (NHC) moiety imbedded in a hybrid material and of the Pd-NHC bond were obtained by dynamic nuclear polarization surface-enhanced NMR spectroscopy (DNP SENS) at natural abundance in short experimental times (hours). Overall, this silica-based hybrid material containing well-defined Pd-NHC sites in a uniform environment displays high activity and selectivity in the semihydrogenation of alkynes into Z-alkenes (see figure)., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Solid-state NMR plays a critical role in establishing the atomic structure of surface species, obtained by the controlled grafting of organometallic complexes onto amorphous oxide supports, a promising strategy towards molecularly defined heterogeneous catalysts. Using one-dimensional or multi-dimensional NMR analysis allows us to map the structure of organometallic residues on surfaces, in a similar fashion that the structure of homogeneous catalysts can be determined using solution NMR techniques. In addition, chemical shift anisotropy analysis can be used as a tool to obtain detail structures and to determine the dynamics of surface species. In combination with DFT calculations we have also shown that the structure of aluminum species can be determined using high-field and ultrafast (27)Al NMR. Finally, we discussed the latest development in Dynamic Nuclear Polarization, which allows the selective enhancements of the NMR signals of surface species, thus reducing the NMR acquisition time by factors up to 10,000. This makes solid-state NMR an indispensible tool in determining structure-property relationship and in the development of advanced materials including catalysts through more rational approach.