Über μ-Carboxylato-μ-hydroxo-bis(triamminkobalt(III))-Komplexe

Report of the preparation, chemical properties, and the infrared-to-ultra-violet spectra of the perchlorates and bromides of the two complex cations [Co₂{ac(OH)₂}(NH₃)₆]³⁺ (where ac = HCO₂, CH₃CO₂; CH₂ClCO₂, CHCl₂CO₂, CCl₃CO₂, CHFCO₂, CHF₂CO₂ und CF₃CO₂) and [Co₂{ac₂(OH)}(NH₃)₆]³⁺ (where ac = CH₂ClCO₂, CHClCO₂ und CCl₃CO₂). The perchlorate, nitrate, bromide and dithionate salts of the tetranuclear complex [Co₄{C₂O₄(OH)₄}(NH₃)₁₂]⁶⁺ are described. The complex reported by WERNER as [Co₂{OH}₂(CH₃CO₂)H₂O(NH₃)₆]Br₃ actually has the formula [Co₂{CH₃CO₂(OH)₂}(NH₃)₆]Br₃ · CH₃COOH.     

μ-Nitro-di-μ-hydroxo-bis[trinitro-kobaltat(III)]-Komplexe

4 complexes containing the anion [Co₂{NO₂(OH)₂}(NO₂)₆]^3? are described. The infrared and Raman spectra are reported and discussed.     

Di-μ-sulfato-μ-hydroxo-bis[triamminkobalt(III)]- und Di-μ-selenato-μ-hydroxo-bis[triamminkobalt(III)]-Komplexe

Preparation and properties of two new complexes containing the cations [Co₂{(SO₄)₂(OH)}(NH₃)₆]⁺ and [Co₂{(SeO₄)₂(OH)}(NH₃)₆]⁺ are described. The absorption spectra in the infrared. visible and ultraviolet region are reported and discussed.     

The Nitrogen‐Assisted Triphenylphosphine Displacement of 3‐Hydroxypyridine and 3‐Aminopyridine Ligands in Palladium(II) Complexes: Crystal Structures of [Pd(PPh3)Br]2{μ,η2‐C5H3N(OH)}2 and [Pd(PPh3)Br]2{μ,η2‐C5H3N(NH2)}2

Treatment of Pd(PPh₃₎₄ with 2‐bromo‐3‐hydroxypyridine [C₅H₃N(OH)Br] and 3‐amino‐2‐bromopyridine [C₅H₃N(NH₂)Br] in dichloromethane at ambient temperature cause the oxidative addition reaction to produce the palladium complex [Pd(PPh₃₎₂{η¹‐C₅H₃N(OH)}(Br)], 2 and [Pd(PPh₃₎₂{η¹‐C₅H₃N(NH₂)}(Br)], 3 , by substituting two triphenylphosphine ligands, respectively. In dichloromethane solution of complexes 2 and 3 at ambient temperature for 3 days, it undergo displacement of the triphenylphosphine ligand to form the dipalladium complexes [Pd(PPh₃)Br]₂{μ,η²‐C₅H₃N(OH)}₂, 4 and [Pd(PPh₃)Br]₂{μ,η²‐C₅H₃N(NH₂)}₂, 5 , in which the two 3‐hydroxypyridine and 3‐aminopyridine ligands coordinated through carbon to one metal center and bridging the other metal through nitrogen atom, respectively. Complexes 4 and 5 are characterized by X‐ray diffraction analyses.     

Die Molekül- und Kristallstruktur von [Co3(CN)2 {(OH)4} (NH3)8][Co2(NO2)6 {(OH)2, NO2}] · H2O

The structure of [Co₃(CN)₂ {(OH)₄} (NH₃)₈] [Co₂(NO₂)₆ {(OH)₂, NO₂}] · H₂O has been determined by X-ray methods. The compound crystallizes in the monoclinic space group C_2h⁵–P2₁/n with a = 7.21, b = 12.38, c = 33.13 Å, β = 94°, Z = 4. The crystals contain trinuclear cations in which three Co(III) atoms are bound to two pairs of oxygen atoms. At the central Co atom there are two CN^– ligands in the cis position. The cation is of symmetry C₂. The anion is found to be a binuclear Co(III) complex. The two Co atoms are bound to two OH^– and one NO₂^– groups.     

Kinetics and Mechanism of Oxidation of S2O32− by a Co‐Bound μ‐Amido‐μ‐Superoxo Complex

In acetate buffer media (pH 4.5–5.4) thiosulfate ion (S₂O₃^2?) reduces the bridged superoxo complex, [(NH₃)₄Co^III(μ‐NH₂,μ‐O₂)Co^III(NH₃)₄]⁴⁺ ( 1 ) to its corresponding μ‐peroxo product, [(NH₃)₄Co^III(μ‐NH₂,μ‐O₂)Co^III(NH₃)₄]³⁺ ( 2 ) and along a parallel reaction path, simultaneously S₂O₃^2? reacts with 1 to produce the substituted μ‐thiosulfato‐μ‐superoxo complex, [(NH₃)₄Co^III(μ‐S₂O₃,μ‐O₂)Co^III(NH₃)₄]³⁺ ( 3 ). The formation of μ‐thiosulfato‐μ‐superoxo complex ( 3 ) appears as a precipitate which on being subjected to FTIR shows absorption peaks that support the presence of Co(III)‐bound S‐coordinated S₂O₃^2? group. In reaction media, 3 readily dissolves to further react with S₂O₃^2? to produce μ‐thiosulfato‐μ‐peroxo product, [(NH₃)₄Co^III(μ‐S₂O₃,μ‐O₂)Co^III(NH₃)₄]²⁺ ( 4 ). The observed rate (k₀) increases with an increase in [T_Thio] ([T_Thio] is the analytical concentration of S₂O₃^2?) and temperature (T), but it decreases with an increase in [H⁺] and the ionic strength (I). Analysis of the log A_t versus time data (A is the absorbance of 1 at time t) reveals that overall the reaction follows a biphasic consecutive reaction path with rate constants k₁ and k₂ and the change of absorbance is equal to {a₁ exp(–k₁t) + a₂ exp(–k₂t)}, where k₁ > k₂.     

Über Reaktionen oxygenierter Kobalt(II)-Chelate. VI. Präparative Darstellung von diastereoisomeren Tetrakis(äthylendiamin)-μ-peroxo-μ-hydroxodikobalt(III)-perchloraten

On Reactions of oxygenated Cobalt(II) Chelates. VI. Preparation of diastereoisomeric tetrakis(ethylenediamine)-μ-peroxo-μl-hydroxo-dicobalt(III) Perchlorates Oxygenation of Co(en)₂²⁺ leads to a mixture of two isomeric forms of [(en)₂Co(O₂, OH)-Co(en)₂] (ClO₄)₃ · H₂O from which the less soluble meso form can be readily crystallized. Further crystallization from the mother liquor yields the racemate ΔΔ/ΔΔ. The pure racemate may be obtained by either of the following methods: (a) By ligand exchange starting from mono bridged [(NH₃)₅CoO₂Co(NH₃)₅] (NO₃)₄ or from doubly bridged [(SCN) (NH₃)₃Co(O₂, OH)Co(NH₃)₃(SCN)] SCN · 2H₂O. (b) By reaction of cis-[Co(en)₂(OH₂)₂]³⁺ with H₂O₂. Reaction (b) proceeds via an intermediate cis-[Co(en)₂(OOH) (OH₂)] (ClO₄)₂ · H₂O which at higher pH reacts with [Co(en)₂(OH) (OH₂)]²⁺ to yield the desired doubly bridged ΔΔ/ΔΔ tetrakis(ethylenediamine)-μ-peroxo-μ-hydroxodikobalt(III)-perchlorate.     

Synthesis,Crystal Structure,and Hydrogen Bonding of μ‐Hydroxo‐μ‐peroxo‐bis[bis(ethylenediamine)cobalt(III)] Squarate

Black‐brown needle‐shaped single crystals of [Co₂(en)₄(O₂)(OH)][C₄O₄]_1.5 · 4H₂O (en = ethylenediamine) were prepared in aqueous solution at room temperature [space group P$\bar{1}$ (no.2) with a = 800.20(8), b = 1225.48(7), c = 1403.84(9) pm, α = 100.282(5), β = 94.515(7), and γ = 95.596(6)°]. The Co³⁺ cations [Co(1), Co(2)] are coordinated in an octahedral manner by four nitrogen atoms stemming from the ethylenediamine molecules and two oxygen atoms each from a hydroxo group and a peroxo group, respectively. Both Co³⁺ coordination polyhedra are connected by a common corner and by the peroxo group leading to the dinuclear [(en)₂Co(O₂)(OH)Co(en)₂]³⁺ cation. The squarate dianions, not bonded to Co³⁺, and the [(en)₂Co(O₂)(OH)Co(en)₂]³⁺ cations are linked by hydrogen bonds forming a three‐dimensional supramolecular network containing water molecules. Magnetic measurements revealed a diamagnetic behavior indicating a low‐spin electron configuration of Co³⁺. The UV/Vis spectra show two LMCT bands [π*(O₂^2–) → d_σ*(Co³⁺)] at 274 and 368 nm and the d–d transition (¹A_1g → ¹T_1g) at 542 nm. Thermoanalytical investigations in air show that the compound is stable up to 120 °C. Subsequent decomposition processes to cobalt oxide are finished at 460 °C.     

Hepta­aqua­tetra‐μ3‐hydroxy‐hexa‐μ2‐l‐leucine‐(l‐leucine)­tetraytterbium(III) tetrachlorozinc(II) tri­chloro­hydroxyzinc(II) tetrachloride octahydrate

The title bimetallic compound, [Yb₄(μ₃‐OH)₄(C₆H₁₃NO₂)₇(H₂O)₇][ZnCl₄][ZnCl₃(OH)]Cl₄·8H₂O, was synthesized at near physiological pH (6.0). The compound exhibits some novel structural features, including an asymmetric [Yb₄(μ₃‐OH)₄(l ‐leucine)₇(H₂O)₇]⁸⁺ complex cation in which four OH groups act as bridging ligands, linking four Yb³⁺ cations into a Yb₄O₄ structural unit. Each pair of adjacent Yb³⁺ ions is further bridged by one carboxy group from a leucine ligand. Water mol­ecules and a monodentate leucine ligand also coordinate to Yb³⁺ ions, completing their eight‐coordinate square‐antiprismatic coordination. The Yb₄(μ₃‐OH)₄(l ‐leu­cine)₇(H₂O)₇]⁸⁺ cation, the [ZnCl₄]²⁻, [ZnCl₃OH]²⁻ and Cl⁻ anions, and the lattice water mol­ecules are linked via hydrogen bonds.     

Die Kristall- und Molekülstruktur von μ-5-Pyrimidincarboxylato (O,O′)-di-μ-hydroxo-bis[triamminkobalt(III)]perchlorat

Crystal and Molecular Structure of μ-5-Pyrimidinecarboxylato(O,O′)-di-μ-hydroxo-bis-[triamminecobalt(III)]perchlorate μ-5-Pyrimidinecarboxylato(O,O′)-di-[μ-hydroxo-bis(triamminecobalt)(III)]perchlorate, [(NH₃)₃Co-μ(OH, OH, C₅H₄N₂O₂)Co(NH₃)₃](ClO₄)₄, crystallizes in the orthorhombic space group Ibca with a = 12.686, b = 13.079, c = 31.785 Å and Z = 8 formula units. The complex cation adopts C₂ symmetry, but no mirror plane is present. The Co? Co separation in the binuclear complex is 2.794 Å. The four-membered ring defined by the two Co atoms and the bridging oxygens is folded along the O? O axis, the interplanar angle being 154°. One of the ClO₄ tetrahedra is disordered over two sites in the crystal.     

Windmill Co4{Co4(μ4‐O)} with 16 Divergent Branches Forming a Family of Metal–Organic Frameworks: Organic Metrics Control Topology,Gas Sorption,and Magnetism

A series of highly connected metal–organic frameworks (MOFs), [Co₈(O)(OH)₄(H₂O)₄(ina)₈](NO₃)₂ ? 2 C₂H₅OH ? 4 H₂O ( 1 ), [Co₈(O)(OH)₄(H₂O)₄(pba)₈](NO₃)₂ ? 8 C₂H₅OH ? 28 H₂O ( 2 ), and [Co₈(O)(OH)₄(H₂O)₄(pbba)₈](NO₃)₂ ? guest ( 3 ), in which ina=isonicotinate, pba=4‐pyridylbenzoate, and pbba=4‐(pyridine‐4‐yl)phenylbenzoate, is reported. These MOFs contain a new secondary building unit (SBU), with a square Co₄(μ₄‐O) central unit having the rare μ₄‐O^2? motif, which is decorated by the other four peripheral cobalt atoms through μ₃‐OH in a windmill‐like shape. This SBU holds 16 divergent connecting organic ligands, pyridyl‐carboxylates, to form three different frameworks. The high porosity of desolvated 2 is shown by the efficient gas absorption of N₂, CO₂, CH₄, and H₂. In addition, 1 and 2 exhibit unusual canted antiferromagnetic behavior with spin‐glass‐like relaxation, with blocking temperatures that are fairly high, 20 K ( 1 ) and 10 K ( 2 ), for cobalt materials. The relationship between the metal clusters and linkers has been studied, in which the size and rotational degrees of freedom of the ligands are found to control the topology, gas sorption, and magnetic properties.     

Cobalt(II) and Cobalt(III) Tri‐tert‐butoxysilanethiolates. Synthesis,Properties, Crystal and Molecular Structures of [Co{μ‐SSi(OBut)3}{SSi(OBut)3}(NH3)]2 and [Co{SSi(OBut)3}2(NH3)4][SSi(OBut)3] Complexes

The heteroleptic neutral tri‐tert‐butoxysilanethiolate of cobalt(II) incorporating ammonia as additional ligand ( 1 ) has been prepared by the reaction of a cobalt(II) ammine complex with tri‐tert‐butoxysilanethiol in water. Complex 1 , dissolved in hexane, undergoes oxidation in an ammonia saturated atmosphere to the ionic cobalt(III) compound 2 . Molecular and crystal structures of 1 and 2 have been determined by single crystal X‐ray structural analysis. 1 forms a dimeric molecule [Co{μ‐SSi(OBu^t)₃}{SSi(OBu^t)₃}(NH₃)]₂ with a folded central Co₂S₂ ring and distorted tetrahedral ligand arrangement at both Co^II atoms (CoNS₃ core). The product 2 is composed of the octahedral Co^III complex cation [Co{SSi(OBu^t)₃}₂(NH₃)₄]⁺ and the tri‐tert‐butoxysilanethiolate anion. Within the crystal two pairs of ions interact by hydrogen bonds forming well separated entities. 1 and 2 are the first structurally characterized cobalt thiolates where metal is also bonded to ammonia and 2 is the first cobalt(III) silanethiolate.     

Structure and Photocatalytic Property of a Cobalt(II) Compound Containing Pentanuclear [Co5(mtpo)2(μ3‐OH)2(μ2‐OH)2(COO)3] Clusters as Building Subunits

The cobalt(II) compound [Co₅(mtpo)₂(pdc)₃(μ₃‐OH)₂(μ₂‐OH)₂(H₂O)₂]_n ( 1 ) (mtpo = 7‐hydroxy‐5‐methyl‐1,3,4‐triazaindolizine, H₂pdc = terephthalic acid) was synthesized by hydrothermal reaction of Co(NO₃)₂, mtpo, and H₂pdc. X‐ray structural analysis shows that compound 1 features a 3D framework containing pentanuclear [Co₅(mtpo)₂(μ₃‐OH)₂(μ₂‐OH)₂(COO)₃] clusters as building subunits. Topological analysis reveals that compound 1 can be simplified into a 6‐connected pcu topological network. Notably, this compound can be used as visible‐light‐driven photocatalyst for photodegradation of MB.     

Mehrkernige Kobaltkomplexe. V. Präparative Herstellung von Tetrakis (äthylendiamin)-μ-peroxo-μ-amido- und μ-peroxo-μ-thiocyanatodikobalt (III)-Komplexen ausgehend von Tetrakis (äthylendiamin)bis-(ammin)-μ-peroxo-dikobalt (III)-tetraperchlorat

Polynuclear Cobalt Complexes. V. Preparation of tetrakis (ethylenediamine)-μ-peroxo-μ-amido and μ-peroxo-μ-thiocyanato-dicobalt (III) complexes starting from tetrakis (ethylenediamine)bis-(ammine)-μ-peroxo-dicobalt (III)-tetraperchlorate Racemic tetrakis (ethylenediamine)-μ-peroxo-μ-amido-dicobalt (III) thiocyanate and its corresponding hydroperoxo- and superoxo-complexes have been isolated from [(en)₂(NH₃)Co(O₂)(NH₃)(en)₂](ClO₄)₄. A new binuclear peroxo complex containing thiocyanate as bridging ligand was prepared by the same method. The stretching frequencies of the CN- and CS-group as well as the NCS-bending frequence in the IR. spectrum of [(en)₂Co(O₂, SCN)Co(en)₂](NO₃)₃ suggest that the μ-thiocyanato group is N-bonded (2050, 750, 475 cm^?1). A comparison of IR. spectra of known singly and doubly bridged μ-peroxo complexes is made. Characteristic absorption bands, assignable to ν(O? O) and ν(Co? O) are given.     

Crystal structure of [Pd(NH3)4][Rh(NH3)(NO2)5]

An XRD analysis is used to study the single crystal of [Pd(NH₃)₄][Rh(NH₃)(NO₂)₅] double complex salt at T = 150(2) K. Crystallographic characteristics are as follows: a = 7.6458(5) ?, b = 9.8813(6) ?, c = 9.5788(7) ?, β = 109.469(2)°, V = 682.30(8) ?³, P2₁/m space group, Z = 2, d _x = 2.553 g/cm³. The geometry of the complex [Rh(NH₃)(NO₂)₅]²⁻ anion is described for the first time: Rh-N(NO₂) distances are 2.020(4)–2.060(3) ?, Rh-N(NH₃) 2.074(4) ?, N(NO₂)-Rh-N(NH₃) trans-angle is 178.8(2)°.     

Reaktion oxygenierter Kobalt (II)-Komplexe. XII. Über einen binuclearen μ-Peroxodikobalt (III)-Komplex mit makrocyclischem Brückenring

Reactions of oxygenated cobalt(II) complexes. XII. A binuclear μ-peroxodicobalt(III) complex with a macrocyclic bridging ring

1 XI: siehe [1].

Singly bridged [(tren) (NH₃) CoO₂(NH₃) (tren)]⁴⁺ reacts with excess tren by replacement of NH₃ in cis-position to the peroxo group and formation of a new type of doubly bridged μ-peroxo complex. An X-ray structure determination of [(tren)-Co(O₂, tren)Co(tren)] (ClO₄)₄ · 2 H₂O showed that the additional tren forms a macrocyclic bridging ring. The conformation of the CoOOCo group is transoid with a dihedral angle of 20°. The crystals are monoclinic with space group P2₁/c. The lattice constants are a = 9,798, b = 26,385, c = 16,385 Å, β = 110,2° with four formula units in the cell. The final R value is 0,124. ClO anions are disordered. The reactions of [(tren)Co(O₂, tren)Co(tren)]⁴⁺ in aqueous solution are compared with those of [(tren) (NH₃) CoO₂Co (NH₃tren)]⁴⁺. In acidic solution the new complex mainly decomposes to Co^II and O₂. In alcaline medium the bridging tren is replaced by an OH bridge, forming the well characterized doubly bridged [(tren)-Co(O₂, OH)Co(tren)]³⁺. Differing from the singly bridged bis (ammino) complex, the reactions of which show no pH dependency at all, the decomposition of the tren bridged complex is H⁺-catalyzed. The kinetic data have been interpreted as (i) preceding fast protonation step which is followed by a conformational change of the bridging ring, (ii) acid hydrolysis of a Co-μ-tren bond and (iii) fast cleavage of the Co-OO bond which is labilized by coordinated H₂O.     

(NH4)6Nd(NO3)9, ein ammoniumreiches ternäres Lanthanidnitrat mit einsamen Nitrationen: (NH4)6[Nd(NO3)6](NO3)3

(NH₄)₆Nd(NO₃)₉, A Ternary Ammonium-Rich Lanthanide Nitrate with Lonesome Nitrate Ions: (NH₄)₆[Nd(NO₃)₆](NO₃)₃ . Single crystals of the ternary ammonium neodymium nitrate (NH₄)₆Nd(NO₃)₉ are obtained from a solution of Nd₂O₃ in a melt of NH₄NO₃. In the crystal structure (monoclinic, C 2/c, Z = 4, a = 1 775.1(4), b = 912.7(3), c = 2 072.3(5) pm; β = 125.56(1)°; R = 0.059, R_w = 0.036) the Nd³⁺ ion is surrounded by six bidentate nitrate ligands so that anionic units [Nd(NO₃)₆]^3? are formed. The units are isolated, but they are incorporated in layers parallel to (010). The structure is held together by a network of hydrogen bonds, built up by NH₄⁺ and NO₃^? ions lying between the layers. Due to the structure, the compound may be described as a double salt like (NH₄)₃[Nd(NO₃)₆] · 3 NH₄NO₃ or, better, as (NH₄)₆[Nd(NO₃)₆](NO₃)₃.     

A mixed‐valence complex of cobalt based on 3‐methoxysalicylaldoxime

A new tetranuclear mixed‐valence cobalt complex, namely di‐μ₂‐azido‐diazidodiethanolbis{μ₂‐2‐[(hydroxyimino)methyl]‐6‐methoxyphenolato}bis{μ₃‐6‐methoxy‐2‐[(oxidoimino)methyl]phenolato}dicobalt(II)dicobalt(III) ethanol disolvate, [Co^II₂Co^III₂(C₈H₇NO₃)₂(C₈H₈NO₃)₂(N₃)₄(C₂H₅OH)₂]·2C₂H₅OH, has been synthesized by the reaction of Co(OAc)₂·4H₂O (OAc is acetate) with 3‐methoxysalicylaldoxime (H₂mosao) in an ethanol solution. In the complex, the four Co cations all display distorted octahedral coordination environments and they are bridged by two κ²,κ¹,κ¹;μ₃‐mosao²⁻ ligands, two κ²,κ²;μ₂‐Hmosao⁻ ligands and two μ₂‐N₃⁻ anions to form a tetranuclear [Co₄N₄O₄] cluster. Adjacent clusters are connected through weak C—H...N and C—H...O interactions, resulting in a two‐dimensional supramolecular network parallel to the ac plane. The magnetic properties of the complex have also been studied.     

Poly[μ2‐(N‐hydroxypyridine‐2‐carboxamidine)‐μ2‐nitrato‐silver(I)]

In the title complex, [Ag(NO₃)(C₆H₇N₃O)]_n or [Ag(NO₃)(pyaoxH₂)] (pyaoxH₂ is N‐hydroxypyridine‐2‐carboxamidine), the Ag⁺ ion is bridged by the pyaoxH₂ ligands and nitrate anions, giving rise to a two‐dimensional molecular structure. Each pyaoxH₂ ligand coordinates to two Ag⁺ ions using its pyridyl and carboxamidine N atoms, and the OH and the NH₂ groups are uncoordinated. Each nitrate anion uses two O atoms to coordinate to two Ag⁺ ions. The Ag...Ag separation via the pyaoxH₂ bridge is 2.869 (1) Å, markedly shorter than that of 6.452 (1) Åvia the nitrate bridge. The two‐dimensional structure is fishscale‐like, and can be described as pyaoxH₂‐bridged Ag₂ nodes that are further linked by nitrate anions. Hydrogen bonding between the amidine groups and the nitrate O atoms connects adjacent layers into a three‐dimensional network.     

The Challenge of Deciphering Linkage Isomers in Mixtures of Oligomeric Complexes Derived from 9‐Methyladenine and trans‐(NH3)2PtII Units

Metal coordination to N9‐substituted adenines, such as the model nucleobase 9‐methyladenine (9MeA), under neutral or weakly acidic pH conditions in water preferably occurs at N1 and/or N7. This leads, not only to mononuclear linkage isomers with N1 or N7 binding, but also to species that involve both N1 and N7 metal binding in the form of dinuclear or oligomeric species. Application of a trans‐(NH₃)₂Pt^II unit and restriction of metal coordination to the N1 and N7 sites and the size of the oligomer to four metal entities generates over 50 possible isomers, which display different feasible connectivities. Slowly interconverting rotamers are not included in this number. Based on ¹H NMR spectroscopic analysis, a qualitative assessment of the spectroscopic features of N1,N7‐bridged species was attempted. By studying the solution behavior of selected isolated and structurally characterized compounds, such as trans‐[PtCl(9MeA‐N7)(NH₃)₂]ClO₄ ? 2H₂O or trans,trans‐[{PtCl(NH₃)₂}₂(9MeA‐N1,N7)][ClO₄]₂ ? H₂O, and also by application of a 9MeA complex with an (NH₃)₃Pt^II entity at N7, [Pt(9MeA‐N7)(NH₃)₃][NO₃]₂, which blocks further cross‐link formation at the N7 site, basic NMR spectroscopic signatures of N1,N7‐bridged Pt^II complexes were identified. Among others, the trinuclear complex trans‐[Pt(NH₃)₂{μ‐(N1‐9MeA‐N7)Pt(NH₃)₃}₂][ClO₄]₆ ? 2H₂O was crystallized and its rotational isomerism in aqueous solution was studied by NMR spectroscopy and DFT calculations. Interestingly, simultaneous Pt^II coordination to N1 and N7 acidifies the exocyclic amino group of the two 9MeA ligands sufficiently to permit replacement of one proton each by a bridging heterometal ion, Hg^II or Cu^II, under mild conditions in water.