Nitrogen-bound Ligands

The structures and rates of interchange of nitrogen atoms in [PtCl(PEt3)2L]BF4, where L is one of the diaza-compounds (19)—(22) have been determined. With 1,10-phenanthroline (19) the rate of intramolecular exchange was too rapid to freeze out on an n.m.r. time-scale and with 1,8-naphthyridine (20) the coalescence 

The C n.m.r. spectrum of (25) shows coalescence of the CO signals with associated pairwise coalescence of the methylcyclopentadienyl signals on increas- 

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Bis-amido tin porphyrins trans (TTP)Sn(N(R)Ph)2 (R = H, Ph) and cis (TTP)Sn(l,2-(NH)2C6H4) have been prepared and shown to be more stable than the analogous Sn—C bonded alkyl or aryl complexes. The increased stability of these nitrogen bound ligands is probably a function of their increased basicity. ... 

At pH 7, [13]aneN3 or [12]-[15]aneN4 accommodate only two nitrogen-bound protons and these dipositive ammonium cations are apparently unable to provide sufficient electrostatic attraction to polycarboxylate anions for ion-pair formation. In contrast, the macrocyclic spermines, pentaamines and hexaamines accommodate more than three nitrogen-bound protons at pH 7 and for these ligands 1 1 associations... 

Formally, in each of these cases the disproportionation produces a positive metal ion and a metal ion in a negative oxidation state. The carbonyl ligands will be bound to the softer metal species, the anion the nitrogen donor ligands (hard Lewis bases) will be bound to the harder metal species, the cation. These disproportionation reactions are quite useful in the preparation of a variety of carbonylate complexes. For example, the [Ni2(CO)6]2 ion can be prepared by the reaction... 

When mixing [(H3N)4RuCl2] and caffeine, the formation of a C(8) carbene ruthe-nium(II) complex was observed in addition to coordination via nitrogen The A-bound ligand isomerizes to give the NHC in the presence of diluted acid. 

A dry 50 mL Schlenk reaction tube was flushed with nitrogen and charged with a mixture of 7 (527mg, l.Ommol), 1,3-dicyclohexylcarbodiimide (1.04g, 5mmol), pentafluorophenol (920 mg, 5 mmol), 4-(dimethylamino)pyridine as the catalyst and the aminomethylated polystyrene (930 mg, 1.07 mmol g ) in dry dichloromethane (20 mL). The mixture was stirred at room temperature for 24h under a N2 atmosphere. The polymer was filtrated, rinsed sequentially with CH2CI2 and acetone and dried at 50 °C in vacuo to yield the polymer-bound ligand 8 as pale yellow beads. 

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