New nickel(II) and palladium(II) complexes with unsymmetrical quadridentate Schiff bases derived from 8-amino-4-methyl-5-azaoct-3-en-2-one. Crystal and molecular structure of [4,10-dimethyl-3-(nitroso-χN)-5,9-(diaza-χ²N)-trideca-3,10-diene-2,12-(dionato-χO)(2–)]nickel(II)

Synthesis and reactivity of an unsymmetrically substituted 16-membered macrocyclic complex of nickel(II) and the crystal structure of its acyclic precursor, (3-acetyl-10-methyl-5,9-diazatrideca-3,8-diene-2, 12-dionato)nickel(II)

“…The asymmetric unit contains two well-separated, independent molecules of (6) (Figure 1 In general, there is good agreement between corresponding bond lengths and angles (Table 2) of the two independent molecules of (6) and with those of related structures (19,25). Any discussion of the structural features of one of the independent molecules of (6) can be as- Compound laC-n.m.r.…”

“…spectroscopy,with the low symmetry of the product being confirmed by the appearance of separate peaks for each carbon atom and the appearance of discrete signals in the 1H n.m.r, spectrum assigned to the four different methyl groups. The palladium(II) complex of this ligand has been reported previously (19) and in the present work the corresponding nickel(II) complex, (6), was prepared as a red solid in ca. 50% yield, from (7), nickel(II) acetate tetrahydrate and sodium hydroxide in warm methanol.…”

“…3-Acetyl-10-methyl-5,9-diazatrideca-3,10-diene-2,12-dione, (7), was prepared by a modification of a literature procedure (19). To a cooled solution of (lb) (15.7g, 0.1tool) in EtOH (100cm 3) was added, dropwise with stirring, a solution of 3-ethoxymethylenepentane-2,4-dione (14.5 g, 0.1 tool) in EtOH (100cm3).…”

“…Thus, the planar sections of the unsaturated six-membered metallochelate rings [O(1)--C(2)--C(3)--C(4)--N(1) and O(2)--C(8)--C(9)--C(10)--N(2)] make angles of 38.7 and 23.1 ~ respectively, with the central NiN20 2 plane, and are inclined at an angle of 61.7 ~ to one another indicating that the structure is substantially bowed [cf. the angle of 38.6 ~ between the planes defined by the aromatic units in the symmetrical nickel(II) complex derived from 1,3-diaminopropane and two equivalents of salicyladehyde] (19).…”

NMR studies on a palladium(II) complex containing an incompletely coordinated facultative pentadentate Schiff base ligand

“…Figure 2 shows also that the dangling pyrrole group in 1(CH 3 COO)H 2 O assumes an E (trans) orientation across the N14 C15 double bond with respect to the metal center, in contrast to Z (cis) orientation of that group in the related nickel complex. 7 Moreover, the plane of this pyrrole ring is slightly (by ca 7°) twisted with respect to the N-1, N-7, N-11, N-14 plane. With respect to the intramolecular structure, the complex ion 1 is indeed crowded, as measured by H15Ð Ð ÐH2, H15Ð Ð ÐC2, C13Ð Ð ÐH20, C13Ð Ð ÐN20, H13BÐ Ð ÐH20, H13BÐ Ð ÐC16 closest approaches, which fall short of the Bondi 8 van der Waals radius sum by >0.23Å.…”