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Novel Bn(2)Cyclam-based zirconium complexes of the type (Bn(2)Cyclam)Zr(X)(X') (3, X = X' = OPh; 4, X = X' = SPh; 5, X = Cl, X' = O(i)Pr) were synthesized in good yields via metathesis routes involving the reaction of the dichloro precursor (Bn(2)Cyclam)Zr(Cl)(2) and the appropriate lithium salts. The molecular structures of compounds 3, 4 and 5, as determined by X-ray crystallographic studies, all confirmed the effective chelation of the Bn(2)Cyclam ligand in a κ(4)-N(2)N(2)' fashion, with the hexa-coordinated Zr center adopting a trigonal prismatic geometry. Complexes 3-5 as well as the diisopropoxide derivative (Bn(2)Cyclam)Zr(O(i)Pr)(2) (2) were all found to initiate the ring-opening polymerization (ROP) of rac-lactide in a controlled manner, as deduced from SEC data and linear correlations between molecular weight numbers (M(n)) and monomer conversion as the ROP proceeds. While initiator 2 polymerizes rac-lactide to afford, as expected, an O(i)Pr-ester-end PLA, the ROP of rac-lactide by species 3 or 4 affords an unusual cyclam-end group PLA, as deduced from MALDI-TOF data. The bonding and the electronic structures of the dialkoxides 2 and 3 were assessed by DFT and their possible influence on the polymerization mechanism is discussed.

The salan zirconium complex of formula [(H2N2O2)ZrCl2] (H2N2O2H2 = HOPh'CH2NH(CH2)2NHCH2Ph'OH, where Ph' = 2,4-(CMe2Ph)C6H2) was synthesized and fully characterized by NMR and single-crystal X-ray diffraction. The solid-state molecular structure of [(H2N2O2)ZrCl2] shows distorted octahedral geometry around the zirconium center with the salan ligand adopting a β-Λ-cis conformation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Trans-disubstituted diamido diamine cyclams support cationic zirconium complexes. • (Bn 2 Cyclam)ZrCl 2 reacts with silver salts to form either neutral or cationic species. • (Bn 2 Cyclam)Zr(C 6 F 5) 2 displays a fluxional behaviour in solution. • (Bn 2 Cyclam)ZrCl} 2 (k 2- N,N' -Bn 2 Cyclam) displays one terminal- and one bridging- cyclam. • [(ansa -η5:η5-Cp 2 CMe 2)ZrCl(HBn 2 Cyclam)] is the first mixed cyclam/cyclopentadienyl complex. Abstract (Bn 2 Cyclam)ZrCl 2 reacts with silver salts to form either neutral or cationic species depending on the nature of the counterion. The reaction of (Bn 2 Cyclam)ZrCl 2 with AgCF 3 COO affords (Bn 2 Cyclam)Zr(OCOCF 3) 2 while with AgPF 6 the cationic species [(Bn 2 Cyclam)ZrCl(CH 3 CN)]PF 6 is formed. Cations of formulas [(All 2 Cyclam)ZrX(L)]+ (X = Me, L = CD 2 Cl 2 ; X, L = η2-CH 2 Ph), [(MeAll 2 Cyclam)Zr(η2-CH 2 Ph)]+ and [(Bn 2 Cyclam)Zr(n Bu)(THF)]+ were prepared by abstraction of one alkyl ligand from (R 2 Cyclam)ZrX 2 (R = All, MeAll, Bn; X = Me, CH 2 Ph, n Bu) using B(C 6 F 5) 3 or [PhMe 2 NH][B(C 6 F 5) 4 ]. (Bn 2 Cyclam)Zr(C 6 F 5) 2 was obtained by reaction of (Bn 2 Cyclam)ZrCl 2 with 2 equiv. of MgBrC 6 F 5. The complex (Bn 2 Cyclam)ZrCl} 2 (k 2- N,N' -Bn 2 Cyclam) displaying a cyclam bridging ligand was obtained either from the 1:1 reaction of (Bn 2 Cyclam)ZrCl 2 with LiNiPr 2 and from the reaction of 2 equiv. of (Bn 2 Cyclam)ZrCl 2 with Li 2 (Bn 2 Cyclam).(THF) 2 in THF. The reaction of LiCpC(Me) 2 CpLi with (Bn 2 Cyclam)ZrCl 2 led to the formation of the mixed cyclam/cyclopentadienyl complex [(ansa -η5:η5-Cp 2 CMe 2)ZrCl(HBn 2 Cyclam)]. [ABSTRACT FROM AUTHOR]

The insertion of isocyanates in (Bn 2Cyclam)ZrX 2 is regioselective; (Bn 2Cyclam)Zr(OR) 2 produces urea-like moieties by the insertion of RN═C═O in the Zr-N amido bonds of the cyclam ring. Depending on the bulkiness of the isocyanate R groups, O- and N-bound ureates are formed. (Bn 2 Cyclam)Zr(NH Bu)2 reacts with MesN═C═O at the terminal Zr-N bonds. [ABSTRACT FROM AUTHOR]

The syntheses of (Bn2Cyclam)Zr(NMe2)2 (1), (Bn2Cyclam)Zr(NH2,6-MePh)Cl (2) and (Bn2Cyclam)Zr(N2,6-MePh) (3) are described. The reactivity of 1, 3, (Bn2Cyclam)Zr(CH2Ph)2 (4) and ((C6H4CH2)2Cyclam)Zr (5) as hydroamination catalysts of aminoalkenes is reported. High conversions of the primary gem-disubstituted aminoalkenes in 5- or 6-member ring N-heterocycles were observed. Reactions of 1, 4 and 5 with CH2＝CHCH2CPh2CH2NH2 gave (Bn2Cyclam)Zr(NHR)2 (6) (R=CH2CPh2CH2CH＝CH2) that on heating converts sequentially into the mono-ortho-metallated species ((C6H4CH2)BnCyclam)Zr(NHR) (7) and the bis-ortho-metallated ((C6H4CH2)2Cyclam)Zr (5), simultaneously with the hydroamination product. [ABSTRACT FROM AUTHOR]