Trivalent and Tetravalent Nickel in Oxime‐Imine‐Amine Coordination

Abstract

Abstract. Model complexes of nickel(III) and nickel(lV) are furnished by hexadentate and tridentate oxime-imine-amine ligands derived by the condensation of biacetyl monoxime with amines. The synthesis, characterisation, structure, redox equilibria and reactivity of these complexes are critically reviewed. Correlations and generalisations pertaining to oxidation state stability, electroprotic equilibria and reaction mechanisms are examined. The possible significance of the present complexes in the context of the nickel-containing methanogenic enzymes is noted.

Kinetic studies of the reduction of nickel oxime complexes by tris(1,10-phenanthroline)cobalt(II) and hydroquinone in aqueous media

“…are presented in Table 1. The data are consistent with reaction (10) with k , , = (1.65 0.06) x lo3 dm3 mol-' s-'. On reduction, there is a subsequent rapid protonation of the oxime bound to Nil' leading to the product ion [Ni(HL')I2+.…”

“…[Co(phen),] ' + as reductant. A spectrophotometric titration, monitored at 500 nm, showed a (1 f 0.005): 1 ratio of Ni"': Co", consistent with the process in equation (10) first order in both oxidant and reductant, corresponding to the rate law (1 I ) with no dependence on pH over the range 3.97-5.78 and only a marginal increase at pH 6.54. The kinetic data…”

Metallomacrocycles: synthesis, x-ray structure, electrochemistry, and ESR spectroscopy of mononuclear and heterodinuclear complexes

“…Complex 4 (0.45 g, 0.50 mmol) was dissolved in 50 mL of MeOH, and a solution of Ni(OAc),-4H20 (0.12 g, 0.50 mmol) in 50 mL of MeOH was added at room temperature. Found: C,38.36;H,3.53;N,3.21. (p-(9, 10,12,13,15,16,18,19,21 (42) Ar refers to the aromatic ring with a "precursor" aldehyde moiety; Ar' refers to the aromatic ring with two imine bonds or to the outer aromatic rings of the terphenyl; Ar" refers to the inner aromatic ring of the terphenyl. After addition of 50 mL of petroleum ether 40-60 the red product crystallized and was filtered off yield 56%; mp (m, 2 H,Ar' H), (m, 2 H,Ar' H), 7.5-7.0 (m, 4 H,Ar H), 6.8-6.5 (m, 2 H,Ar H),8 H,OCH,),12 H,OCH,); I3C NMR (DMSO-d,; 358 K) 6 157.3 (d, N=CH), 154.9 (s, Ar C-2), 151.8 (s, Ar C-3), 140.2 (s, A I ' C-1,2), 127.9, 126.3 (d, Ar C-6, Ar' C-4,5), 120.6 (s, Ar C-1), 117.5,116.8,115.3 (d,5,6),OCH,); IR (KBr) 1613 (N=C) cm-I; mass spectrum m / e 606.141 (M+ -Ba(C104)2, calcd 606.151).…”

“…Ba 1 Ni 1 CI 1 c12 0 1 5 0 1 6 0 1 9 0 2 2 0 2 5 0 2 8 0 3 1 0 3 4 0 3 7 0 4 4 0 5 1 0 5 2 0 5 3 0 5 4 0 6 0 0 6 1 0 6 2 0 6 3 (2) 0.113 (2) 0.154 (2) 0.086 (2) 0.12573 (6) 0.0423 (1) 0.0636 (3) 0.0340 (6) 0.0391 (7) 0.1479 (7) 0 (1) 0.23892 (9) 0.6474 (4) 0.1 143 (9) 0.279 (1) (9) 0.0874 (9) 0.671 (2) 0.724 (2) 0.576 (2) 0.635 (2) 0.725 (2) -0.0000 (2) -0.2411 (5) (2) 0.437 (2) 0.385 (2) 0.305 (2) 0.135 (2) 0.054 (2) 0.032 (2) 0.178 (2) 0.274 (2) 0.435 (2) 0.450 (2) 0.012 (2) 3.01 (2) 3.08 (6) 4.3 (1) 6.4 (2) (7) 13.3 (8) 14.6 (8) 10.7 (7) 10.0 (6) 19 (1) 17 (1) 19 (1) 3.2 (3); 3.6 (3); 4.8 ( 5 ) ; 6.2 (6)' 6.3 (6); 5.3 (6); 5.0 (5); 3.5 (4)' 4.0 (5)' 3.4 (4). 4.2 (5)* 3.8 (4); 3.3 (4); 2.9 (4); 2.9 (4); 5.2 (5); 6.0 ( 6 ) ; 5.2 (5); 7.1 (7)* 5.9 (6)* 4.7 (5); 6.0 (6); 8.6 (8) 8.5 (8) (1) 3.9 (5); 0.120 (1) 4.1 (4); 0.029 (2) 4.9 (5); -0.045 ...…”

“…In principle the behavior of dimetallic complexes can be quite different from that of the monometallic analogues when there is only a small distance between the two metal centers.9 Ciampolini et al 10 have demonstrated the interaction of two cations in dinickel and dicopper complexes of , -linked bis(cyclam) ligands. The interaction was dependent on the nature of the bridge between the two rings.…”