Unusual NH Activation of 2‐Aminopyrimidine: Supramolecular Assembly into an AgI Metal–Organic Framework

A rare example of coordination at the amino group of NH₂pym (2‐aminopyrimidine) relevant to N? H activation is described that leads to a novel Ag^I–imide 3D metal–organic framework (MOF). The coordination of Ag^I to NH₂pym produced an electron‐withdrawing effect and thus increased its acidity, which facilitated the N? H activation and the subsequent formation of the Ag–imide bond. A cooperative metalation/deprotonation process for the N? H activation of NH₂pym is suggested. Interestingly, photoluminescence of 1 is switched on at the low temperature of 77 K.     

Nitrogen incorporation in saturated aliphatic C6–C8 hydrocarbons and ethanol in low‐pressure nitrogen plasma generated by a hollow cathode discharge ion source

Ion/molecule reactions of saturated hydrocarbons (n‐hexane, cyclohexane, n‐heptane, n‐octane and isooctane) in 28‐Torr N₂ plasma generated by a hollow cathode discharge ion source were investigated using an Orbitrap mass spectrometer. It was found that the ions with [M+14]⁺ were observed as the major ions (M: sample molecule). The exact mass analysis revealed that the ions are nitrogenated molecules, [M+N]⁺ formed by the reactions of N₃⁺ with M. The reaction, N₃⁺ + M → [M+N]⁺ + N₂, were examined by the density functional theory calculations. It was found that N₃⁺ abstracts the H atom from hydrocarbon molecules leading to the formation of protonated imines in the forms of R′R″C?NH₂⁺ (i.e. C–H bond nitrogenation). This result is in accord with the fact that elimination of NH₃ is the major channel for MS/MS of [M+N]⁺. That is, nitrogen is incorporated in the C–H bonds of saturated hydrocarbons. No nitrogenation was observed for benzene and acetone, which was ascribed to the formation of stable charge‐transfer complexes benzene????N₃⁺ and acetone????N₃⁺ revealed by density functional theory calculations. Copyright © 2016 John Wiley & Sons, Ltd.     

Monitoring and Understanding the Paraelectric–Ferroelectric Phase Transition in the Metal–Organic Framework [NH4][M(HCOO)3] by Solid‐State NMR Spectroscopy

The paraelectric–ferroelectric phase transition in two isostructural metal–organic frameworks (MOFs) [NH₄][M(HCOO)₃] (M=Mg, Zn) was investigated by in situ variable‐temperature ²⁵Mg, ⁶⁷Zn, ¹⁴N, and ¹³C solid‐state NMR (SSNMR) spectroscopy. With decreasing temperature, a disorder–order transition of NH₄⁺ cations causes a change in dielectric properties. It is thought that [NH₄][Mg(HCOO)₃] exhibits a higher transition temperature than [NH₄][Zn(HCOO)₃] due to stronger hydrogen‐bonding interactions between NH₄⁺ ions and framework oxygen atoms. ²⁵Mg and ⁶⁷Zn NMR parameters are very sensitive to temperature‐induced changes in structure, dynamics, and dielectric behavior; stark spectral differences across the paraelectric–ferroelectric phase transition are intimately related to subtle changes in the local environment of the metal center. Although ²⁵Mg and ⁶⁷Zn are challenging nuclei for SSNMR experiments, the highly spherically symmetric metal‐atom environments in [NH₄][M(HCOO)₃] give rise to relatively narrow spectra that can be acquired in 30–60 min at a low magnetic field of 9.4 T. Complementary ¹⁴N and ¹³C SSNMR experiments were performed to probe the role of NH₄⁺–framework hydrogen bonding in the paraelectric–ferroelectric phase transition. This multinuclear SSNMR approach yields new physical insights into the [NH₄][M(HCOO)₃] system and shows great potential for molecular‐level studies on electric phenomena in a wide variety of MOFs.     

Estimation of peptide N–Cα bond cleavage efficiency during MALDI‐ISD using a cyclic peptide

Matrix‐assisted laser desorption/ionization in‐source decay (MALDI‐ISD) induces N–C_α bond cleavage via hydrogen transfer from the matrix to the peptide backbone, which produces a c′/z? fragment pair. Subsequently, the z? generates z′ and [z + matrix] fragments via further radical reactions because of the low stability of the z?. In the present study, we investigated MALDI‐ISD of a cyclic peptide. The N–C_α bond cleavage in the cyclic peptide by MALDI‐ISD produced the hydrogen‐abundant peptide radical [M + 2H]⁺? with a radical site on the α‐carbon atom, which then reacted with the matrix to give [M + 3H]⁺ and [M + H + matrix]⁺. For 1,5‐diaminonaphthalene (1,5‐DAN) adducts with z fragments, post‐source decay of [M + H + 1,5‐DAN]⁺ generated from the cyclic peptide showed predominant loss of an amino acid with 1,5‐DAN. Additionally, MALDI‐ISD with Fourier transform‐ion cyclotron resonance mass spectrometry allowed for the detection of both [M + 3H]⁺ and [M + H]⁺ with two ¹³C atoms. These results strongly suggested that [M + 3H]⁺ and [M + H + 1,5‐DAN]⁺ were formed by N–C_α bond cleavage with further radical reactions. As a consequence, the cleavage efficiency of the N–C_α bond during MALDI‐ISD could be estimated by the ratio of the intensity of [M + H]⁺ and [M + 3H]⁺ in the Fourier transform‐ion cyclotron resonance spectrum. Because the reduction efficiency of a matrix for the cyclic peptide cyclo(Arg‐Gly‐Asp‐D‐Phe‐Val) was correlated to its tendency to cleave the N–C_α bond in linear peptides, the present method could allow the evaluation of the efficiency of N–C_α bond cleavage for MALDI matrix development. Copyright © 2016 John Wiley & Sons, Ltd.     

Tris(3,5‐dimethylpyrazolyl)methane‐Based Heterobimetallic Complexes that Contain Zn and CdTransition‐Metal Bonds: Synthesis,Structures, and Quantum Chemical Calculations

Reactions of the tris(3,5‐dimethylpyrazolyl)methanide amido complexes [M′{C(3,5‐Me₂pz)₃}{N(SiMe₃)₂}] (M′=Mg ( 1 a ), Zn ( 1 b ), Cd ( 1 c ); 3,5‐Me₂pz=3,5‐dimethylpyrazolyl) with two equivalents of the acidic Group 6 cyclopentadienyl (Cp) tricarbonyl hydrides [MCp(CO)₃H] (M=Cr ( 2 a ), Mo ( 2 b )) gave different types of heterobimetallic complex. In each case, two reactions took place, namely the conversion of the tris(3,5‐dimethylpyrazolyl)methanide ligand (Tpmd*) into the ‐methane derivative (Tpm*) and the reaction of the acidic hydride M?H bond with the M′?N(SiMe₃)₂ moiety. The latter produces HN(SiMe₃)₂ as a byproduct. The Group 2 representatives [Mg(Tpm*){MCp(CO)₃}₂(thf)] ( 3 a / b ) form isocarbonyl bridges between the magnesium and chromium/molybdenum centres, whereas direct metal–metal bonds are formed in the case of the ions [Zn(Tpm*){MCp(CO)₃}]⁺ ( 4 a / b ; [MCp(CO)₃]^? as the counteranion) and [Cd(Tpm*){MCp(CO)₃}(thf)]⁺ ( 5 a / b ; [Cd{MCp(CO)₃}₃]^? as the counteranion). Complexes 4 a and 5 a / b are the first complexes that contain Zn?Cr, Cd?Cr, and Cd?Mo bonds (bond lengths 251.6, 269.8, and 278.9 pm, respectively). Quantum chemical calculations on 4 a / b* (and also on 5 a / b* ) provide evidence for an interaction between the metal atoms.     

Ion–molecule reaction in the gas phase 3—nucleophilic substitution of 17ξ-R-5α,14β-androstane-14,17ξ-diols under [NH4]+ chemical ionization conditions1

Under Ammonia chemical Ionization conditions the source decompositions of [M + NH₄]⁺ ions formed from epimeric tertiary steroid alchols 14 OH_β, 17OH_α or 17 OH_β substituted at position 17 have been studied. They give rise to formation of [M + NH₄? H₂O]⁺ dentoed as [MH_sH]⁺, [M_sH? H₂O]⁺, [M_sH? NH₃]⁺ and [M_sH? NH₃? H₂O]⁺ ions. Stereochemical effects are observed in the ratios [M_sH? H₂O]⁺/[M_sH? NH₃]⁺. These effects are significant among metastable ions. In particular, only the [M_sH]⁺ ions produced from trans-diol isomers lose a water molecule. The favoured loss of water can be accounted for by an S_N2 mechanism in which the insertion of NH₃ gives [M_sH]⁺ with Walden inversion occurring during the ion-molecule reaction between [M + NH₄]⁺ + NH₃. The S_N1 and S_Ni pathways have been rejected.     

Racemic dipeptide glycyl‐dl‐leucine at 120 K

The structure of glycyl‐dl ‐leucine, C₈H₁₆N₂O₃, has been determined at 120 K by single‐crystal X‐ray diffraction. In addition to three N—H?O‐type hydrogen bonds of the positively charged RNH₃⁺ group of the zwitterionic mol­ecule, an intermolecular N—H?O contact exists between the peptide bond and the carboxyl­ate group. Four hydrogen‐bond cycles were identified, giving a complex pattern.     

Insertion of Molecular Oxygen in Transition‐Metal Hydride Bonds,Oxygen‐Bond Activation,and Unimolecular Dissociation of Metal Hydroperoxide Intermediates. Short Communication

Thermal activation of molecular oxygen is observed for the late‐transition‐metal cationic complexes [M(H)(OH)]⁺ with M=Fe, Co, and Ni. Most of the reactions proceed via insertion in a metal? hydride bond followed by the dissociation of the resulting metal hydroperoxide intermediate(s) upon losses of O, OH, and H₂O. As indicated by labeling studies, the processes for the Ni complex are very specific such that the O‐atoms of the neutrals expelled originate almost exclusively from the substrate O₂. In comparison to the [M(H)(OH)]⁺ cations, the ion? molecule reactions of the metal hydride systems [MH]⁺ (M=Fe, Co, Ni, Pd, and Pt) with dioxygen are rather inefficient, if they occur at all. However, for the solvated complexes [M(H)(H₂O)]⁺ (M=Fe, Co, Ni), the reaction with O₂ involving O? O bond activation show higher reactivity depending on the transition metal: 60% for the Ni, 16% for the Co, and only 4% for the Fe complex relative to the [Ni(H)(OH)]⁺/O₂ couple.     

NH3‐Driven Benzene C−H Activation with O2 that Opens a New Way for Selective Phenol Synthesis

Catalytic benzene C?H activation toward selective phenol synthesis with O₂ remains a stimulating challenge to be tackled. Phenol is currently produced industrially by the three‐steps cumene process in liquid phase, which is energy‐intensive and not environmentally friendly. Hence, there is a strong demand for an alternative gas‐phase single‐path reaction process. This account documents the pivotal confined single metal ion site platform with a sufficiently large coordination sphere in β zeolite pores, which promotes the unprecedented catalysis for the selective benzene hydroxylation with O₂ under coexisting NH₃ by the new inter‐ligand concerted mechanism. Among alkali and alkaline‐earth metal ions and transition and precious metal ions, single Cs⁺ and Rb⁺ sites with ion diameters >0.300 nm in the β pores exhibited good performances for the direct phenol synthesis in a gas‐phase single‐path reaction process. The single Cs⁺ and Rb⁺ sites that possess neither significant Lewis acidic?basic property nor redox property, cannot activate benzene, O₂, and NH₃, respectively, whereas when they coadsorbed together, the reaction of the inter‐coadsorbates on the single alkali‐metal ion site proceeds concertedly (the inter‐ligand concerted mechanism), bringing about the benzene C?H activation toward phenol synthesis. The NH₃‐driven benzene C?H activation with O₂ was compared to the switchover of the reaction pathways from the deep oxidation to selective oxidation of benzene by coexisting NH₃ on Pt₆ metallic cluster/β and Ni₄O₄ oxide cluster/β. The NH₃‐driven selective oxidation mechanism observed with the Cs⁺/β and Rb⁺/β differs from the traditional redox catalysis (Mars‐van Krevelen) mechanism, simple Langmuir‐Hinshelwood mechanism, and acid?base catalysis mechanism involving clearly defined interaction modes. The present catalysis concept opens a new way for catalytic selective oxidation processes involving direct phenol synthesis.     

Kinetics and mechanism of the oxidation of 4‐methyl‐3‐thiosemicarbazide by acidic bromate

The oxidation of 4‐methyl‐3‐thiosemicarbazide (MTSC) by bromate and bromine was studied in acidic medium. The stoichiometry of the reaction is extremely complex, and is dependent on the ratio of the initial concentrations of the oxidant to reductant. In excess MTSC and after prolonged standing, the stoichiometry was determined to be H₃CN(H)CSN(H)NH₂ + 3BrO₃^? → 2CO₂ + NH₄⁺ + SO₄^2? + N₂ + 3Br^? + H⁺ (A). An interim stoichiometry is also obtained in which one of the CO₂ molecules is replaced by HCOOH with an overall stoichiometry of 3H₃CN(H)CSN(H)NH₂ + 8BrO₃^? → CO₂ + NH₄⁺ + SO₄^2? + HCOOH + N₂ + 3Br^? + 3H⁺ (B). Stoichiometry A and B are not very different, and so mixtures of the two were obtained. Compared to other oxidations of thiourea‐based compounds, this reaction is moderately fast and is first order in both bromate and substrate. It is autocatalytic in HOBr. The reaction is characterized by an autocatalytic sigmoidal decay in the consumption of MTSC, while in excess bromate conditions the reaction shows an induction period before autocatalytic formation of bromine. In both cases, oxybromine chemistry, which involves the initial formation of the reactive species HOBr and Br₂, is dominant. The reactions of MTSC with both HOBr and Br₂ are fast, and so the overall rate of oxidation is dependent upon the rates of formation of these reactive species from bromate. Our proposed mechanism involves the initial cleavage of the C? N bond on the azo‐side of the molecule to release nitrogen and an activated sulfur species that quickly and rapidly rearranges to give a series of thiourea acids. These thiourea acids are then oxidized to the sulfonic acid before cleavage of the C? S bond to give SO₄^2?, CO₂, and NH₄⁺. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 237–247, 2002     

B−B Bond Nucleophilicity in a Tetraaryl μ‐Hydridodiborane(4) Anion

The tetraaryl μ‐hydridodiborane(4) anion [ 2 H]^? possesses nucleophilic B?B and B?H bonds. Treatment of K[ 2 H] with the electrophilic 9‐H‐9‐borafluorene (HBFlu) furnishes the B₃ cluster K[ 3 ], with a triangular boron core linked through two BHB two‐electron, three‐center bonds and one electron‐precise B?B bond, reminiscent of the prominent [B₃H₈]^? anion. Upon heating or prolonged stirring at room temperature, K[ 3 ] rearranges to a slightly more stable isomer K[ 3 a ]. The reaction of M[ 2 H] (M⁺=Li⁺, K⁺) with MeI or Me₃SiCl leads to equimolar amounts of 9‐R‐9‐borafluorene and HBFlu (R=Me or Me₃Si). Thus, [ 2 H]^? behaves as a masked [:BFlu]^? nucleophile. The HBFlu by‐product was used in situ to establish a tandem substitution‐hydroboration reaction: a 1:1 mixture of M[ 2 H] and allyl bromide gave the 1,3‐propylene‐linked ditopic 9‐borafluorene 5 as sole product. M[ 2 H] also participates in unprecedented [4+1] cycloadditions with dienes to furnish dialkyl diaryl spiroborates, M[R₂BFlu].     

Calcium‐Catalyzed Arene C−H Bond Activation by Low‐Valent AlI

The low‐valent ß‐diketiminate complex (^DIPPBDI)Al is stable in benzene but addition of catalytic quantities of [(^DIPPBDI)CaH]₂ at 20 °C led to (^DIPPBDI)Al(Ph)H (^DIPPBDI=CH[C(CH₃)N‐DIPP]₂, DIPP=2,6‐diisopropylphenyl). Similar Ca‐catalyzed C?H bond activation is demonstrated for toluene or p‐xylene. For toluene a remarkable selectivity for meta‐functionalization has been observed. Reaction of (^DIPPBDI)Al(m‐tolyl)H with I₂ gave m‐tolyl iodide, H₂ and (^DIPPBDI)AlI₂ which was recycled to (^DIPPBDI)Al. Attempts to catalyze this reaction with Mg or Zn hydride catalysts failed. Instead, the highly stable complexes (^DIPPBDI)Al(H)M(^DIPPBDI) (M=Mg, Zn) were formed. DFT calculations on the Ca hydride catalyzed arene alumination suggest that a similar but more loosely bound complex is formed: (^DIPPBDI)Al(H)Ca(^DIPPBDI). This is in equilibrium with the hydride bridged complex (^DIPPBDI)Al(μ‐H)Ca(^DIPPBDI) which shows strongly increased electron density at Al. The combination of Ca‐arene bonding and a highly nucleophilic Al center are key to facile C?H bond activation.     

Heterolytic activation of C?H bond in methane with (HNCHCHNH)M(CH3) (M = Pd+, Pt+, Rh+, Ir+, Rh,Ir): Comparative density functional study of activation mechanisms

Activation of methane by oxidative addition and σ‐bond metathesis has been investigated for (N‐N)M(CH₃) (M = Pd⁺, Pt⁺, Rh⁺, Ir⁺, Rh, Ir; N‐N = (HN?CH? CH?NH) using different density functional approaches. The pathway of oxidative addition is in general favored, the exceptions being Pd⁺ and Rh⁺. Oxidative addition is clearly more favorable for the third‐row metal complexes than those of the second row. The third‐row metal complexes also tend to have a lower activation barrier for σ‐bond metathesis than those of the second row. In each case, the oxidative addition is preceded by formation of a sigma complex. The bonding energies of these complexes are significantly stronger for the cationic systems. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

Bis­[bis­(diethyl­enetri­amine)­zinc(II)] hexa­cyano­ferrate tetrahydrate

In the crystal structure of the title compound, [Zn(C₄H₁₃N₃)₂]₂[Fe(CN)₆]·4H₂O, the asymmetric unit is formed by a [Zn(dien)₂]²⁺ cation (dien = diethyl­enetri­amine, NH₂CH₂CH₂NHCH₂CH₂NH₂), water mol­ecules and half of the [Fe(CN)₆]^4? anion which is related by inversion symmetry through the Fe atom. The geometry around the Zn and Fe atoms is distorted octahedral and octahedral, respectively. Intramolecular O—H?O hydrogen bonds involving the water mol­ecules, and intermolecular O—H?N hydrogen bonds involving the water mol­ecules and the anions, result in an infinite chain. Intramolecular O—H?O and N—H?N, and intermolecular O—H?N, N—H?O and N—H?N hydrogen bonds form a three‐dimensional framework.     

Hypervalent radical formation probed by electron transfer dissociation of zwitterionic tryptophan and tryptophan‐containing dipeptides complexed with Ca2+ and 18‐crown‐6 in the gas phase

The relationship between peptide structure and electron transfer dissociation (ETD) is important for structural analysis by mass spectrometry. In the present study, the formation, structure and reactivity of the reaction intermediate in the ETD process were examined using a quadrupole ion trap mass spectrometer equipped with an electrospray ionization source. ETD product ions of zwitterionic tryptophan (Trp) and Trp‐containing dipeptides (Trp‐Gly and Gly‐Trp) were detected without reionization using non‐covalent analyte complexes with Ca²⁺ and 18‐crown‐6 (18C6). In the collision‐induced dissociation, NH₃ loss was the main dissociation pathway, and loss related to the dissociation of the carboxyl group was not observed. This indicated that Trp and its dipeptides on Ca²⁺(18C6) adopted a zwitterionic structure with an NH₃⁺ group and bonded to Ca²⁺(18C6) through the COO^? group. Hydrogen atom loss observed in the ETD spectra indicated that intermolecular electron transfer from a molecular anion to the NH₃⁺ group formed a hypervalent ammonium radical, R‐NH₃, as a reaction intermediate, which was unstable and dissociated rapidly through N–H bond cleavage. In addition, N–C_α bond cleavage forming the z₁ ion was observed in the ETD spectra of Trp‐GlyCa²⁺(18C6) and Gly‐TrpCa²⁺(18C6). This dissociation was induced by transfer of a hydrogen atom in the cluster formed via an N–H bond cleavage of the hypervalent ammonium radical and was in competition with the hydrogen atom loss. The results showed that a hypervalent radical intermediate, forming a delocalized hydrogen atom, contributes to the backbone cleavages of peptides in ETD. Copyright © 2015 John Wiley & Sons, Ltd.     

Strong N−X⋅⋅⋅O−N Halogen Bonds: A Comprehensive Study on N‐Halosaccharin Pyridine N‐Oxide Complexes

A study of the strong N?X???^?O?N⁺ (X=I, Br) halogen bonding interactions reports 2×27 donor×acceptor complexes of N‐halosaccharins and pyridine N‐oxides (PyNO). DFT calculations were used to investigate the X???O halogen bond (XB) interaction energies in 54 complexes. A simplified computationally fast electrostatic model was developed for predicting the X???O XBs. The XB interaction energies vary from ?47.5 to ?120.3 kJ mol^?1; the strongest N?I???^?O?N⁺ XBs approaching those of 3‐center‐4‐electron [N?I?N]⁺ halogen‐bonded systems (ca. 160 kJ mol^?1). ¹H NMR association constants (K_XB) determined in CDCl₃ and [D₆]acetone vary from 2.0×10⁰ to >10⁸ m ^?1 and correlate well with the calculated donor×acceptor complexation enthalpies found between ?38.4 and ?77.5 kJ mol^?1. In X‐ray crystal structures, the N‐iodosaccharin‐PyNO complexes manifest short interaction ratios (R_XB) between 0.65–0.67 for the N?I???^?O?N⁺ halogen bond.     

A quasi‐diamondoid hydrogen‐bonded framework in an­hydro­us sulfanilic acid

The title compound (C₆H₇NO₃S) exists as a zwitterion (4‐ammonio­benzene­sulfonate), ⁺H₃NC₆H₄SO₃^?, and these units are linked into a three‐dimensional framework by two distinct two‐centre N—H?O hydrogen bonds [H?O 1.84 and 1.87 Å; N?O 2.767 (2) and 2.746 (2) Å; N—H?O 166 and 172°] and a planar three‐centre N—H?(O)₂ hydrogen bond [H?O 2.03 and 2.37 Å; N?O 2.816 (2) and 2.877 (2) Å; N—H?O 162 and 111°; O?H?O 86°].     

CH Bond Activation by Early Transition Metal Carbide Cluster Anion MoC3−

Although early transition metal (ETM) carbides can activate C?H bonds in condensed‐phase systems, the electronic‐level mechanism is unclear. Atomic clusters are ideal model systems for understanding the mechanisms of bond activation. For the first time, C?H activation of a simple alkane (ethane) by an ETM carbide cluster anion (MoC₃^?) under thermal‐collision conditions has been identified by using high‐resolution mass spectrometry, photoelectron imaging spectroscopy, and high‐level quantum chemical calculations. Dehydrogenation and ethene elimination were observed in the reaction of MoC₃^? with C₂H₆. The C?H activation follows a mechanism of oxidative addition that is much more favorable in the carbon‐stabilized low‐spin ground electronic state than in the high‐spin excited state. The reaction efficiency between the MoC₃^? anion and C₂H₆ is low (0.23±0.05) %. A comparison between the anionic and a highly efficient cationic reaction system (Pt⁺+C₂H₆) was made. It turned out that the potential‐energy surfaces for the entrance channels of the anionic and cationic reaction systems can be very different.     

Ion–Molecule Reactions of “Rollover” Cyclometalated [Pt(bipy−H)]+ (bipy=2,2′‐bipyridine) with Dimethyl Ether in Comparison with Dimethyl Sulfide: An Experimental/Computational Study

The ion–molecule reactions of dimethyl ether with cyclometalated [Pt(bipy?H)]⁺ were investigated in gas‐phase experiments, complemented by DFT methods, and compared with the previously reported ion–molecule reactions with its sulfur analogue. The initial step corresponds in both cases to a platinum‐mediated transfer of a hydrogen atom from the ether to the (bipy?H) ligand, and three‐membered oxygen‐ and sulfur‐containing metallacycles serve as key intermediates. Oxidative C? C bond coupling (“dehydrosulfurization”), which dominates the gas‐phase ion chemistry of the [Pt(bipy?H)]⁺ ion with dimethyl sulfide, is practically absent for dimethyl ether. The competition in the formation of C₂H₄ and CH₂X (X=O, S) in the reactions of [Pt(bipy?H)]⁺ with (CH₃)₂X (X=O, S) as well as the extensive H/D exchange observed in the [Pt(bipy?H)]⁺/(CH₃)₂O system are explained in terms of the corresponding potential‐energy surfaces.