Synthese und Struktur von N,N,N‴,N‴‐Tetraisobutyl‐N′,N″‐isophthaloylbis(thioharnstoff) und Dimethanol‐bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))dicobalt(II)

Synthesis and Structure of N,N,N?,N?‐Tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and Dimethanol‐bis(N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))dicobalt(II) The synthesis and the crystal structure of the ligand N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and its Co^II‐complex are reported. The ligand co‐ordinates quadridentately forming a di‐bischelate. The donor atoms O and S are arranged in cis‐position around the central Co^II ions. In addition the co‐ordination geometry is determined by methanol molecules resulting in the co‐ordination number five. The complex crystallizes in the space group P1 (Z = 1) with two additional methanol molecules per formula unit. The free ligand crystallizes in the space group P1 (Z = 2) with one methanol molecule per formula unit. It shows the typical keto form of N‐acylthioureas with a protonated central N atom. The structures of both acylthiourea fragments come close to E,Z′‐configurations.     

Synthesis and Spectroscopic Study of Some New Phosphoramidates,Crystal Structures of N‐Benzoyl‐N′,N″‐bis(azetidinyl)phosphoric Triamide and N‐Benzoyl‐N′,N″‐bis(hexamethylenyl)phosphoric Triamide

Some new N‐carbonyl, phosphoramidates with formula C₆H₅C(O)N(H)P(O)R₂ (R = NC₃H₆ ( 1 ), NC₆H₁₂ ( 2 ), NHCH₂CH=CH₂ ( 3 ), N(C₃H₇)₂ ( 4 )) and CCl₃C(O)N(H)P(O)R′₂ (R′ = NC₃H₆ ( 5 ), NHCH₂CH=CH₂ ( 6 )) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR and IR spectroscopy and elemental analysis. The structures were determined for compounds 1 and 2 . Compound 1 exists as two crystallographically independent molecules in crystal lattice. Both compounds 1 and 2 produced dimeric aggregates via intermolecular ‐P=O…H‐N‐ hydrogen bonds, which in compound 2 is a centrosymmetric dimer. In compounds with four‐membered ring amine groups, ³J(P,C)>²J(P,C), in agreement with our previous studies about five‐membered ring amine groups. Also, ³J(P,C) values in compounds 1 and 5 are greater than in compounds with five‐, six‐ and seven‐membered ring amine groups.     

Structures and Spectroscopy of some Adducts of Coinage Metal(I) Cyanides with ‘Tetrahedral’‐Unidentate‐N‐Bases

Crystallization of copper(I) cyanide from piperidine (‘pip’) solution yields an adduct of CuCN : pip (3 : 4) ratio, as established by a single crystal X‐ray structure determination, which also shows the complex to have a single‐stranded ···Cu(CN)Cu(CN)···spine (C,N scrambled), one‐third of the copper atoms carrying a pair of pip ligands, the others only one. Crystallization of silver(I) cyanide from piperidine (‘pip’) or cyclohexylamine (‘CyNH₂’) solutions yields adducts of the unusual AgX : unidentate‐N‐base (1 : 2) stoichiometry. The CyNH₂ adduct is, unusually for cyanide complexes of this type, mononuclear with a trigonal planar silver atom, [(NC)Ag(H₂NCy)₂], the AgCN component lying along the intersection of two crystallographic mirror planes which bisect and relate the H₂NCy ligands (Ag‐C, N 2.067(3), 2.335(2) Å; N‐Ag‐N, C 80·80(6), 139.60(4)°). In the pip adduct, the immediate silver atom environment is also three‐coordinate (Ag‐C; N, N 2.080(1); 2.288, 2.443(1) Å; N‐Ag‐N 88·34(4), N‐Ag‐C 144.47(4), 125.07(4), (Σ357.₉°) perturbed toward two‐coordination, but the silver atom environment geometry is further perturbed from planarity by the parallel approach of an inversion‐related molecule (Ag···C′ 2.926(1) Å (Ag···Ag′ 3.1842(2)°) forming a loose, albeit still discrete, dimer. Key features in the IR spectra of the above compounds and of AgCN : pip (1 : 1) and CuCN : CyNH₂ (2 : 3) are assigned and discussed in terms of the structures or of proposed structures in the case of the latter two adducts. The structure of [ClAg(pip)₃], adventitiously obtained, is also described (Ag‐Cl 2.471(3); Ag‐N 2.147(13), 2.188(7) (x2) Å; Cl‐Ag‐N 96.1(3), 98.5(2), N‐Ag‐N 116.3(2) (x2), 122.1(3)°).     

Syntheses,Characterization and X‐Ray Structures of the first Copper(I) and Silver(I) Complexes with ATT (ATT = 6‐Aza‐2‐thiothymine)

The reaction of copper(I) chloride with 6‐aza‐2‐thiothymine (ATT, 1 ) and triphenylphosphane in methanol/chloroform gives [(ATT)CuCl(PPh₃)] ( 2 ) as a neutral complex. [(ATT)Ag(NO₃)(PPh₃)₂]·MeOH ( 3 ) can be obtained by the reaction of 1 with silver(I) nitrate and triphenylphosphane in methanol/chloroform in excellent yields and the single crystals of 3 can be obtained from acetonitril solution. Both complexes were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for 2 at —80 °C: space group I2/a with a = 1859.3(1), b = 1143.2(1), c = 2208.2(1) pm, β = 104.84(1)°, Z = 8, R₁ = 0.0355 and for 3 at —80 °C: space group P2₁/c with a = 1344.1(1), b = 1553.6(1), c = 1977, 3(3) pm, β = 105.26(1)°, Z = 4, R₁ = 0.0436.     

Cis‐trans Isomerism in Copper(II) Complexes with N‐acyl Thiourea Ligands

The N‐acyl thiourea complexes bis[N,N‐diethyl‐N′‐(p‐nitrobenzoyl)‐thioureato]copper(II) ( 1a,1b ) and bis(N,N‐diphenyl‐N′‐benzoylthioureato)copper(II) ( 2a,2b ) crystallize in each case in two modifications. X‐ray structural analysis shows that 1a and 1b are cis‐trans isomers. This is very unusual for N‐acyl thioureato complexes because with exception of one platinum(II) complex up to now only cis complexes have been found. In contrast X‐ray structural analysis of both forms 2a and 2b of the other complex shows no cis‐trans pair. Both modifications are cis complexes. In solution both isomers of the copper(II) complexes are observable by EPR spectroscopy.     

Structural and Spectroscopic Studies of Halocuprate(I) and Haloargentate(I) Complexes [M2XnX′4−n]2−

The complexes [Cu₂Br₄]^2?, [Cu₂I₄]^2?, [Cu₂I₂Br₂]^2?, [Cu₂I₃Cl]^2?, [Ag₂Cl₄]^2? have been characterized as their isomorphous bis(triphenylphosphoranylidene)ammonium ([Ph₃PNPPh₃]⁺ = PNP⁺) salts by single crystal structural determinations. All anions show the centrosymmetric doubly halogen‐bridged forms [XM(μ‐X)₂MX]^2? with three‐coordinate metal atoms that have been observed in [M₂X₄]^2? complexes with other large organic cations. In [Cu₂I₂Br₂]^2? the iodide ligands occupy the bridging positions and the bromide the terminal positions, while in [Cu₂I₃Cl]^2?, obtained in an attempt to prepare [Cu₂I₂Cl₂]^2?, two of the iodide ligands occupy the bridging positions with the third iodide and the chloride ligand occupying two statistically disordered terminal positions. In [Ag₂Cl₄]^2? the distortion from ideal trigonal coordination of the metal atom is greater than in the copper complexes, but less than in other previously reported [Ag₂Cl₄]^2? complexes with organic cations. The ν(MX) bands have been assigned in the far‐IR spectra, and confirm previous observations regarding the unexpectedly simple IR spectra of [Cu₂X₄]^2? complexes.     

Synthese,Strukturen, NMR‐ und EPR‐Untersuchungen der binuklearen Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(selenoureato))‐Komplexe des NiII und CuII

Synthesis, Structures, NMR and EPR Investigations of Binuclear Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(selenoureato)) Complexes of Ni^II and Cu^II The synthesis of binuclear Cu^II and Ni^II complexes of the quadridentate ligand N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(selenourea) and their crystal structures are reported. The complexes crystallize monoclinic, P2₁/c (Z = 2). In the EPR spectra of the binuclear Cu^II complex exchange‐coupled Cu^II‐Cu^II pairs were observed. In addition the signals of a mononuclear Cu^II species are observed what will be explained with the assumption of an equilibrium between the binuclear Cu^II‐complex (Cu^II‐Cu^II pairs) and oligomeric complexes with “isolated” Cu^II ions. Detailed ¹³C and ⁷⁷Se NMR investigations on the ligand and the Ni^II complex allow an exact assignment of all signals of the heteroatoms.     

Synthese,Strukturen und X‐/Q‐Band‐EPR‐Untersuchungen von N,N‐Diethyl‐N′‐3,5‐di(trifluormethyl)benzoylthioureato‐Komplexen des CuII,NiII und PdII sowie EPR‐spektroskopische Charakterisierung eines CuII‐CuII‐Dimers

The synthesis and the structures of (i) the ligand N,N‐Diethyl‐N′‐3,5‐di(trifluoromethyl)benzoylthiourea HEt₂dtfmbtu and (ii) the Ni^II and Pd^II complexes of HEt₂dtfmbtu are reported. The ligand coordinates bidendate forming bis chelates. The Ni^II and the Pd^II complexes are isostructural. The also prepared Cu^II complex could not be characterized by X‐ray analysis. However, the preparation of diamagnetically diluted powders Cu/Ni(Et₂dtfmbtu)₂ and Cu/Pd(Et₂dtfmbtu)₂ suitable for EPR studies was successful. The EPR spectra of the Cu/Ni and Cu/Pd systems show noticeable differences for the symmetry of the CuS₂O₂ unit in both complexes: the Cu/Pd system is characterized by axially‐symmetric g< and A ^cu tensors; for the Cu/Ni system g and A ^Cu have rhombic symmetry. EPR studies on frozen solutions of the Cu^II complex show the presence of a Cu^II‐Cu^II dimer which is the first observed for Cu^II acylthioureato complexes up to now. The parameters of the fine structure tensor were used for the estimation of the Cu^II‐Cu^II distance.     

Bis[N,N′‐bis(2‐nitrocinnamaldehyde)phenylenediimine]copper(I) Perchlorate

The complex [Cu(nitroca₂ph)₂]ClO₄, where nitroca₂ph is N,N′‐bis(2‐nitrocinnamaldehyde)phenylenediimine, crystallizes in the triclinic space group with a = 13.167(1), b = 13.209(1), c = 14.465(1) Å, α = 83.209(9)°, β = 68.438(2)°, γ = 70.803(2)°, V = 2209.4(3) ų, Z = 2, D_calc = 1.527 mg/m³. The coordination polyhedron about the Cu(I) atom is best described as a distorted tetrahedron. 2‐nitroca₂en acts as a bidentate ligand coordinating via two N atoms to the copper. The four Cu–N distances are 2.04 (2), 2.038(2), 2.046(2), and 2.062(2) Å.     

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and its Complexes with Copper(II) Chloride and Copper(II) Perchlorate

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole (hnt), prepared by alkylation of 3‐nitro‐1, 2, 4‐triazole with 2‐chloroethanol, was found to react with copper(II) chloride and copper(II) perchlorate in acetonitrile/ethanol solutions giving complexes [Cu₂(hnt)₂Cl₄(H₂O)₂] and[Cu(hnt)₂(H₂O)₃](ClO₄)₂, respectively. They are the first examples of coordination compounds with a neutral N‐substituted 3‐nitro‐1, 2, 4‐triazole ligand. 1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and the obtained complexes were characterized by NMR and IR spectroscopy, X‐ray, and thermal analyses. [Cu₂(hnt)₂Cl₄(H₂O)₂] presents a dinuclear chlorido‐bridged complex in which hnt acts as a chelating bidentate ligand, coordinated to the metal by a nitrogen atom of the triazole ring and an oxygen atom of the nitro group, and the copper atoms are inconsiderably distorted octahedral coordination. [Cu(hnt)₂(H₂O)₃](ClO₄)₂comprises a mononuclear complex cation, in which two nitrogen atoms of two hnt ligands in trans configuration and three water oxygen atoms form a square pyramidal environment around the copper atom, which is completed to an distorted octahedron with a bifurcated vertex due to two additional elongated Cu–O bonds with two nitro groups. In both complexes, Cu–O bonds with the nitro groups may be considered as semi‐coordinated.     

Synthesis and Spectroscopic Characterization of the Benzaldehyde Schiff Base of S‐Allyldithiocarbazate and its Copper(II) Complex and the X‐ray Crystal Structure of Bis[S‐allyl‐β‐N‐benzylidene)dithiocarbazato]Copper(II)

S‐allyl‐β‐N‐(benzylidene)dithiocarbazate (sabdtc, 1 ), prepared from hydrazine hydrate, carbon disulfide, allyl bromide and benzaldehyde, reacts with copper(II) nitrate in ethanol solution to form the complex Cu(sabdtc)₂ ( 2 ). 1 function as a single negatively charged bidentate chelating ligand and coordinates via the azomethine nitrogen atom and thioenolate sulfur atom to the metal ion. 1 and 2 were characterized by elemental analyses, ¹H NMR, ¹³C NMR, UV/Vis, IR, and mass spectra. Spectroscopic evidences suggest a four‐coordinate distorted square planar structure for 2 . The molecular and crystal structure of 2 was determined by single crystal X‐ray analysis. Crystallographic data for 2 at 291(2) K: space group C2/c, a = 20.340(3), b = 15.503(3), c = 7.659(1) Å, β = 95.96(2)°, Z = 4, R₁ = 0.044 and wR2 = 0.0689.     

Synthesis and Structural Characterization of Some Novel Trialkylsilyl‐substituted Lithium Benzyl Complexes [Li(tmeda)][CHRSiMe2R′] (R = Ph, 3,5‐Me2C6H3; R′ = Me,tBu, Ph)

The reactions of PhCH₂SiMe₃ ( 1 ), PhCH₂SiMe₂^tBu ( 2 ), PhCH₂SiMe₂Ph ( 3 ), 3,5‐Me₂C₆H₃CH₂SiMe₃ ( 4 ), and 3,5‐Me₂C₆H₃CH₂SiMe₂^tBu ( 5 ) with ⁿBuLi in tetramethylethylenediamine (tmeda) afford the corresponding lithium complexes [Li(tmeda)][CHRSiMe₂R′] (R, R′ = Ph, Me ( 6 ), Ph, ^tBu ( 7 ), Ph, Ph ( 8 ), 3,5‐Me₂C₆H₃, Me ( 9 ), and 3,5‐Me₂C₆H₃, ^tBu ( 10 )), respectively. The new compounds 5 , 7 , 8 , 9 and 10 have been characterized by ¹H and ¹³C NMR spectroscopy, compounds 7 , 8 and 9 also by X‐ray structure analysis.     

Structural Studies of a Copper(II) Complex with Inequivalent 2‐Acetylpyridine 3‐Piperidylthiosemicarbazonato Ligands and a Nickel(II) Complex with Different Modes of Coordination by the Two Thiosemicarbazonato Moieties of 1‐Phenylglyoxal Bis{N(4)‐diethylthiosemicarbazone}

The crystal structure of a copper(II) complex of 2‐acetylpyridine 3‐piperidylthiosemicarbazone, [Cu(Acpip)₂], indicates a tridentate, monoanionic ligand (i. e., pyridine nitrogen, imine nitrogen and thiolato sulfur atoms) and a bidentate, monanionic ligand (i. e., imine nitrogen and thiolato sulfur atoms). The stereochemistry approaches square pyramidal with the bidentate ligand occupying an apical (imine nitrogen atom) and basal (thiolato sulfur atom) position. The structure of a nickel(II) complex of 1‐phenylglyoxal N(4)‐diethylthiosemicarbazone, [Ni(Pg4DE)], has a 4‐6‐5 trichelate system rather than the 5‐5‐5 system common to bis(thiosemicarbazones). Coordination of the hydrazinic nitrogen atom of the “phenyl arm” along with the thiolato sulfur atom provides the 4‐membered chelate ring.     

An Alternative Method for the Preparation of Diphenylboron Chelates. The Crystal and Molecular Structures of (Pyridine‐2‐acetyloximato)diphenylboron and (1‐Phenylazo‐2‐naphtholato)diphenylboron

A convenient method for the preparation of diphenylboron chelates from ammonium tetraphenylborate is described. A variety of five‐ or six‐membered O,O‐, N,O‐ and N,N‐chelates were obtained in yields from 60 to 90 %. The isolated compounds were characterized by elemental analysis, IR spectroscopy and multinuclear magnetic resonance spectroscopy (¹H, ¹³C, and ¹¹B). The crystal and molecular structures of (pyridine‐2‐acetyloximato)diphenylboron and (1‐phenylazo‐2‐naphtholato)diphenylboron were determined by X‐ray diffraction on single crystals.     

Syntheses and X‐Ray Crystal Structures of New Copper(I) and Silver(I) Complexes containing Thione Ligands

The reaction of [(Ph₃P)₂CuCl]₂ with 4‐amino‐6‐methyl‐1,2,4‐triazine‐thione‐5‐one (AMTTO, 1 ) in methanol and further recrystallization from methanol/acetone solution gives [(C₄H₄N₃SON(=CMe₂)Cu(PPh₃)₂Cl] ( 2 ) as a neutral complex. [(C₄H₄N₃SON(=CMe₂)Ag(PPh₃)₂]NO₃ ( 4 ) can be obtained in excellent yield by the reaction of [(AMTTO)₂Ag]NO₃ ( 3 ) with triphenylphosphane in methanol/acetone. Both complexes were characterized by infrared spectroscopy, elemental analyses as well as by X‐ray diffraction studies. Crystal data for 2 at –80 °C: space group P1 with a = 1233.8(1), b = 1389.7(1), c = 1417.1(1) pm, α = 89.36(1)°; β = 65.10(1)°, γ = 65.95(1)°, Z = 2, R₁ = 0.0582 and for 4 at –80 °C: space group P1, with a = 1193.3(1), b = 1308.5(1), c = 1385.3(1) pm, α = 94.69(1)°, β = 109.14(1)°, γ = 93.42(1)°, Z = 2, R₁ = 0.0716.     

A Structural Study of the Iminodiacetate Moiety Conformation in N‐(1‐adamantyl)‐iminodiacetate(2‐) Copper(II) Complexes

N,N‐bis(carboxymethyl)‐1‐adamantylamine acid (H₂BCAA) or N‐(1‐adamantyl)‐iminodiacetic acid forms zwitterions that are intra‐stabilized by a ‘bifurcated’ N⁺‐H···O(carboxyl)₂ interaction. In the crystal, both half‐protonated carboxyl groups of H₂BCAA^± are involved in linear O‐H···O inter‐molecular bridges of 2.46Å. In the studied BCAA‐Cu^II derivatives, the iminodiacetate‐moiety of the BCAA chelating ligand exhibits a mer‐NO₂ conformation in [Cu(BCAA)(H₂O)₂] ( 1 ) and [Cu(BCAA)(Him)]₂ ( 2 ), but a fac‐O₂+N(apical) conformation in [Cu(BCAA)(bpy)(H₂O)]·3.5H₂O ( 3 ) [Him = imidazole, bpy =2,2′‐bipyridine]. In clear contrast, dipyridylamine (dpya), as auxiliary ligand, seems to be unable to promote the fac‐O₂+N(apical) conformation in BCAA, as reveal the structures of two new salts with the trinuclear cation [(dpya)₂Cu‐μ₂‐Cu(BCAA)₂‐Cu(dpya)₂]²⁺ and the anions [Cu(BCAA)₂]^2? ( 4 ) or NO₃^? ( 5 ), respectively.     

Synthesis of Phosphanes Bearing 2‐Imino‐1,3‐thiazolidine Ligands – X‐Ray Analyses and NMR Spectroscopy

Pseudo‐ephedrine derived 2‐imino‐1,3‐thiazolidine 1 reacts with tris(diethylamino)phosphane by stepwise replacement of the diethylamino group to give the mono‐, bis‐ and tris(imino)phosphanes 2 , 3 and 4 , respectively, of which 4 could be isolated in pure state. The analogous reaction with diethylamino‐diphenylphosphane affords the imino‐diphenylphosphane 5 . The iminophosphanes react with sulfur or selenium to give the corresponding phosphorus(V) compounds. In contrast, the reaction of the iminophosphanes with oxygen is very slow; anhydrous trimethylamine N‐oxide reacts in the melt with the phosphanes to give the oxides 4(O) and 5(O) . The molecular structures of 4(O) (in mixture with 4 ), 4(Se) , 5(S) and 5(Se) were determined by X‐ray analysis. In all cases the ring‐sulfur and the phosphorus atoms are in cis‐positions at the C=N bonds. The analogous solution structures were determined by ¹H, ¹³C, ¹⁵N, ³¹P and ⁷⁷Se NMR spectroscopy. In the case of the compounds 5 , 5(O) , 5(S) and 5(Se) the isotope‐induced chemical shifts ¹δ^14/15N(³¹P) were determined, using INEPT‐HEED experiments.     

Synthese und Charakterisierung von Cobalt(II)‐ und Kupfer(I)‐Komplexen mit Guanidin‐Pyridin‐Hybridliganden

Syntheses and Structures of Cobalt(II) and Copper(I) Complexes with Guanidine‐Pyridine Hybridligands The guanidine‐pyridine hybridligands N‐(1,3‐dimethylimidazolidin‐2‐ylidene)‐2‐(pyridine‐2‐yl)ethanamine (DMEGepy, L1 ) and 1,1,3,3‐tetramethyl‐2‐(2‐(pyridine‐2‐yl)ethyl)guanidine (TMGepy, L2 ) have been synthesized and characterized. The reaction of DMEGepy with CoCl₂ and TMGepy with CuI lead to the mononuclear complexes {N‐(1,3‐dimethylimidazolidin‐2‐ylidene)‐2‐(pyridine‐2‐yl)ethanamine}cobalt(II) dichloride ( 1 ) and {1,1,3,3‐tetramethyl‐2‐(2‐(pyridine‐2‐yl)ethyl)guanidine}copper(I) iodide ( 2 ). By the characterization of these complexes we are able to compare the complexation chemistry of the hybridguanidine and bisguanidine ligands with regard to the various N donor functions systematically.     

Synthesis and Characterization of N,N‐Di‐substituted Acylthiourea Copper(II) Complexes

A series of six N,N‐di‐substituted acylthiourea ArC(O)NHC(S)NRR′ ligands (denoted as HLⁿ) [Ar = 1‐Naph: NRR′ = NPh₂, HL¹ ( 1 ); N(iPr)Ph, HL² ( 2 ). Ar = Mes: NRR′ = NPh₂, HL⁴ ( 3 ); N(iPr)Ph, HL⁵ ( 4 ); NEt₂, HL⁶ ( 5 ). Ar = Ph: NRR′ = N(iPr)Ph, HL⁸ ( 6 )] were synthesized and characterized. These ligands were deprotonated to form Cu^II complexes through metathesis or combined redox reaction with copper halides. The structures of the complexes were investigated with single‐crystal X‐ray diffraction. The reaction of the 1‐naphthalene derivative HL¹ ( 1 ) with CuBr in the presence of sodium acetate produced cis‐CuL¹₂ ( 7 ), where the deprotonated ligand is bound to the Cu^II atom in a bidentate‐(O, S) coordination mode. Similarly treatment of HL² ( 2 ) with NaOAc and CuCl resulted in the formation of the cis‐arranged product [cis‐CuL²₂ ( 8 )]. The reaction of mesityl derivative HL⁴ ( 3 ) and CuBr with and without the addition of NaOAc gave the cis‐CuL⁴₂ ( 9 ) and cis‐(HL⁴)₂CuBr ( 10 ), respectively. In contrast, reaction of HL⁵ ( 4 ) and CuI in the presence of NaOAc resulted in trans‐CuL⁵₂ ( 11 ). Alternatively trans‐CuL⁶₂ ( 12 ) was obtained by the reaction of diethyl‐substituted HL⁶ ( 5 ) with CuCl₂ in the absence of a base.