The thioethers (4-tert-butyl-2,6-bis((2-(diphenylphosphino)ethylimino)methyl)phenyl)(tert-butyl)sulfane (tBuL3) and (4-tert-butyl-2,6-bis((2-(diphenylphosphino)ethylamino)methyl)phenyl)(tert-butyl)sulfane (tBuL4) react readily with [Pd(NCMe)2Cl2] to give the dinuclear palladium thiophenolate complexes [(L3)Pd2(Cl)2]+ and [(L4)Pd2(micro-Cl)]2+ (HL3=2,6-bis((2-(diphenylphosphino)ethylimino)methyl)-4-tert-butylbenzenethiol, HL4=2,6-bis((2-(diphenylphosphino)ethylamino)methyl)-4-tert-butylbenzenethiol). The chlorides in could be replaced by neutral (MeCN) and anionic ligands (NCS-, N3-, I-, CN-) to give the dinuclear PdII complexes [(L3)Pd2(NCMe)2]3+, [(L3)Pd2(SCN)2]+, [(L3)Pd2(N3)2]+, [(L3)Pd2(I)2]+, and [(L3)Pd2(CN)2]+. The acetonitrile ligands in are readily hydrated to give the corresponding amidato complex [(L3)Pd2(NHCOMe)]2+. All complexes were isolated as perchlorate salts and studied by infrared, 1H, and 31P NMR spectroscopy. In addition, complexes [ClO4].EtOH, [ClO4]2, [ClO4], [ClO4].EtOH, and [ClO4]2.MeCN.MeOH have been characterized by X-ray crystallography. The dipalladium complex was found to catalyse the vinyl-addition polymerization of norbornene in the presence of MAO (methylalumoxane) and B(C6F5)3/AlEt3.
The thioethers 4-tert-butyl-2,6-bis((2-(dimethylamino)ethylimino)methyl)phenyl(tert-butyl)sulfane (tBu-L3) and 4-tert-butyl-2,6-bis((2-(dimethylamino)ethylimino)methyl)phenyl(tert-butyl)sulfane (tBu-L4) react with PdCl2(NCMe)2 to give the dinuclear palladium thiophenolate complexes [(L3)Pd2Cl2]+ (2) and [(L4Pd2(mu-Cl)]2+ (3) (HL3= 2,6-bis((2-(dimethylamino)ethylimino)methyl)-4-tert-butylbenzenethiol, HL4 = 2,6-bis((2-(dimethylamino)ethylamino)methyl)-4-tert-butylbenzenethiol). The chloride ligands in could be replaced by neutral (NCMe) and anionic ligands (NCS-, N3-, CN-, OAc-) to give the diamagnetic Pd(II) complexes [(L3)Pd2(NCMe)2]3+ (4), [(L3)Pd2(NCS)2]+ (5), [(L3)Pd2(N3)2]+ (6), [{(L3)Pd2(mu-CN)}2]4+ (7) and [(L3)Pd2(OAc)]2+ (9). The nitrile ligands in and in [(L3)Pd2(NCCH2Cl)2]3+ are readily hydrated to give the corresponding amidato complexes [(L3)Pd2(CH3CONH)]2+ (8) and [(L3)Pd2(CH2ClCONH)]2+ (10). The reaction of [(L3)Pd2(NCMe)2]3+ with NaBPh4 gave the diphenyl complex [(L3)Pd2(Ph)2]+ (11). All complexes were either isolated as perchlorate or tetraphenylborate salts and studied by IR, 1H and 13C NMR spectroscopy. In addition, complexes 2[ClO4], 3[ClO4]2, 5[BPh4], 6[BPh4], 7[ClO4]4, 9[ClO4]2, 10[ClO4]2 and 11[BPh4] have been characterized by X-ray crystallography.
The macrobicyclic azathioether ligands L1 and L2 were investigated regarding their capability to form complexes with divalent palladium. L1 represents a cyclophane‐like ligand system comprising two 4‐tert‐butyl‐2, 6‐bis(aminomethyl)thiophenolate units, which are linked by an ethylene and two 3‐aza‐1, 5‐pentylene units to give two seventeen‐membered dithia‐triaza crowns fused at the common ArSCH2CH2SAr fragment. L2 is the hexa‐N‐methylated derivative of L1. Treatment of L1 and L2 with two equivalents of [PdCl2(CH3CN)2] gave the new complexes [(L1)Pd2Cl]+ (1) and [(L2)Pd2Cl2]2+ (2), respectively, which were isolated as perchlorate salts and characterized by elemental analysis, IR and NMR spectroscopy and by X‐ray crystallography. In 1, L1 acts as a septadentate ligand to give two distorted square‐planar PdN3S and PdN3Cl units, respectively. The structure of 2 shows L2 to be hexacoordinate, yielding two distorted square‐planar PdN2SCl units leaving two NMe groups dangling. NMR spectroscopic studies reveal that both complexes retain their solid‐state structures in solution. The reaction of L2 with one equivalent of [PdCl2(CH3CN)2] is accompanied by a bond cleavage reaction of one of the two aliphatic thioether bonds to afford the dinuclear complex [(L3)Pd2Cl2]Cl (3·Cl) of the ring‐opened 24‐membered hexaaza‐vinylthioether/thiophenolate derivative (L3)‐. The crystal structure determination of 3·Cl reveals two distorted‐square planar PdN2ClS units which are bridged by the thiophenolate sulfur atom of (L3)‐. The vinyl‐thioether moiety and the two remaining amine donors of (L3)‐ do not interact with the two palladium ions. The X‐ray structure analysis of the free macrocycle L2 demonstrates that the C‐S bond lengths become elongated upon coordination to the palladium(II) ions.
The ability of the tetraaza‐dithiophenolate ligand H2L2 (H2L2 = N,N′‐Bis‐[2‐thio‐3‐aminomethyl‐5‐tert‐butyl‐benzyl]propane‐1,3‐diamine) to form dinuclear chromium(III) complexes has been examined. Reaction of CrIICl2 with H2L2 in methanol in the presence of base followed by air‐oxidation afforded cis,cis‐[(L2)CrIII2(μ‐OH)(Cl)2]+ (1a) and trans,trans‐[(L2)CrIII2(μ‐OH)(Cl)2]+ (1b). Both compounds contain a confacial bioctahedral N2ClCrIII(μ‐SR)2(μ‐OH)CrIIIClN2 core. The isomers differ in the mutual orientation of the coligands and the conformation of the supporting ligand. In 1a both Cl− ligands are cis to the bridging OH function. In 1b they are in trans‐positions. Reaction of the hydroxo‐bridged complexes with HCl yielded the chloro‐bridged cations cis,cis‐[(L2)CrIII2(μ‐Cl)(Cl)2]+ (2a) and trans,trans‐[(L2)CrIII2(μ‐Cl)(Cl)2]Cl (2b), respectively. These bridge substitutions proceed with retention of the structures of the parent complexes 1a and 1b.
The reactivity of Co111 amine-thiolate complexes with terminal and bridging thiolate func tions towards oxidizing agents has been investigated. The mononuclear Co N3S3 complex [Coni(L1)] (2) (H3L 1 represents the hexadentate ligand /V,jV',./V"-Tris(2-thio-benzyl)-1,1,1 -tris-(aminomethyl)ethane) featuring three terminal thiolate ligands, and the binuclear N3Com-(Ai-S)3ComN3 complex [Coni2(L2)]3+ (4) (H3L2 = N, A^/V''-Tris-[2-thio-3-aminomethyl-5-terrbutyl-benzyl]-l,l,l-tris(aminomethyl)ethane) featuring three bridging thiolates were selected. Hydrogen peroxide was the oxidizing agent. Whereas the thiolato-bridged complex 4 is resis tant towards oxidation by hydrogen peroxide, 2 undergoes a ligand-based oxidation reaction to give the amine-sulfinate complex [Co(L'')] 5, where all three terminal thiolates have been oxidized to sulfinates without gross structural changes of the parent complex 2. In contrast to 4, the cyclic voltammogram of 2 reveals an irreversible oxidation wave at E = +0.52 V vs SCE which can be attributed to a ligand-centered oxidation reaction. 4 and 5 have been structurally characterized by X-ray crystallography.
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