A new ruthenium hydride complex of the aminocyclopentadienyl ligand (Cp-N)RuH(PPh3)2 (Cp-N = C5H4CH2CH2NMe2, 1) has been prepared and characterized by X-ray diffraction. Protonation of 1 with excess HPF6 leads to the dicationic derivative [(Cp-NH)RuH2(PPh3)2](PF6)2 (2), in which both the metal and the amino substituent have been protonated. Addition of 1 equiv of HBF4·Et2O to 1 leads to the complex [(Cp-N)Ru(PPh3)2](BF4) (3), containing a chelating amino cyclopentadienyl ligand after elimination of H2. However, using (HNEt3)(BPh4) or (HPBu3)(BPh4) as protonating agent, it is possible to form [(Cp-NH)RuH(PPh3)2](BPh4) (4), which was isolated as yellow crystals of 4·H2O upon addition of undistilled methanol and characterized by X-ray crystallographic analysis. A fluxional process exchanging the ammonium proton and the hydride without changing the thermodynamic state of the system could be established by 1H NMR, and activation energies of 11 kcal·mol-1 were calculated for 4·H2O and the product resulting from in situ addition of [HNEt3][BPh4] to 1, whereas an activation energy of 10.1 kcal·mol-1 was found for the product resulting from in situ addition of [HPBu3][BPh4] to 1. A density functional study (B3PW91) was carried out, and the dihydrogen bond in the model system for 4 was calculated to be 1.545 Å, in excellent agreement with T 1 measurements (1.52 Å). The proposed mechanism for the fluxional process does not involve a proton transfer within the dihydrogen bond.

Six thallium() tetrazolates have been synthesized by either the addition of an alcoholic solution of the appropriate tetrazole to an ethanolic solution of thallium ethoxide, or from the sodium salt of the tetrazole with Tl 2 SO 4 . Seven diphenylthallium-substituted mono-and bis-tetrazoles have been synthesized by a condensation route involving the appropriate tetrazole and diphenylthallium hydroxide. 1-Diphenylthallyl-5-phenyltetrazole has also been prepared by a cycloaddition reaction between diphenylthallium azide and benzonitrile. The structures of [Tl(18-crown-6) ϩ ] 2 -[C 2 N 10 2Ϫ ], Ph 2 TlN 4 CPhؒMeOH, 1,4-(Ph 2 TlN 4 C) 2 C 4 H 8 ؒ2MeOH and 1,2-(Ph 2 TlN 4 C) 2 C 6 H 4 ؒPh 2 TlClؒ2MeOHؒ2H 2 O have been determined. The last three compounds generate supramolecular structures which incorporate sixmembered Tl 2 N 4 rings. The last two contain the first examples of tetrazoles which utilise all four available ring nitrogens for co-ordination.

Treatment of Cp*M(NO)(X)Cl complexes (M = Mo, W; X, = CH2SiMe3, CH2CMe3, NHCMe3, OCMe3, Cl) with lithium phosphides can result in one of three different types of reactions. Some reactions involve the starting material undergoing metathesis of a chloro ligand, and others effect reduction of the organometallic reactant, while a third class results in a scrambling of the ligands of the starting complex. Reactions of Cp*M(NO)(X)Cl with LiPPh2 lead to formation of the respective phosphido-containing complexes Cp*M(NO)(X)(PPh2) [M = W, X = CH2SiMe3 (1), CH2CMe3 (2), NHCMe3 (3), OCMe3 (4); M = Mo, X = NHCMe3 (5)]. In contrast, treatment of the molybdenum complexes Cp*Mo(NO)(X)Cl (X = CH2SiMe3, CH2CMe3, OCMe3) with LiPPh2 under identical conditions affords no isolable products. When metathesis of the chloro ligands in the Cp*M(NO)Cl2 complexes of Mo and W is attempted with either LiPPh2 or LiPPhH, the only isolable products formed are those resulting from the reduction of the organometallic reactant. Thus, treatment of Cp*W(NO)Cl2 with 1 equiv of LiPPh2 leads to isolation of the NO bond-cleaved product, [Cp*W(NO)(Cl)](μ-N)[Cp*W(O)Cl] (6), in low (15%) yield, while reactions of Cp*M(NO)Cl2 (M = Mo, W) with 2 equiv of either LiPPh2 or LiPPhH afford modest yields of the bimetallic products [Cp*W(NO)(μ-PPh2)]2 (7), [Cp*Mo(NO)(μ-PPh2)]2 (8), and [Cp*Mo(NO)(μ-PHPh)]2 (9). Finally, the reaction of Cp*W(NO)(NHCMe3)Cl with LiPPhH induces a ligand-scrambling process in which an amide ligand from one molecule of the starting material is transferred to the tungsten center of another to produce Cp*W(NO)(NHCMe3)2 (10). A similar example of ligand scrambling occurs during the reaction of Cp*Mo(NO)(CH2SiMe3)Cl with LiPPhH. In this case the unexpected product {[Cp*Mo(NO)(CH2SiMe3)2][Li(THF)]}2 (11, isolated in 3% yield) has also undergone a further one-electron reduction at the metal center. The solid-state molecular structures of compounds 9−11 have been established by X-ray crystallographic analyses.

[Cp*Mo(NO) (CH,SiMe,),] exhibits three principal types of reaction with the various lithium reagents investigated during this study, namely: regioselective deprotonation, reduction, and addition. Deprotonation of the reactant, achieved by treatment with lithium amide