Paul G. Watson

Coordination chemistry in and of sulfur dioxide

Abstract The review describes the syntheses of metal salts with weakly interacting anions (AlCl4 −, AsF6 −, SbF6 −) in the poorly coordinating solvent SO2. The metal centers in the resulting complexes might be considered as almost ‘naked’, their unusual coordination chemistry is discussed.

Ruthenium and osmium acyl fluoride complexes. Crystal structure of [OC-6-13][RuF2(CO)2(PPh3)2]·CD2Cl2

Fluoroacyl complexes of ruthenium and osmium have been identified in the oxidative addition of XeF2 to [M(CO)3(PPh3)2](M = Ru or Os) in dichloromethane. The mechanism of reaction, probed by the addition of BF3, involves oxidation of the metal centre by XeF+ followed by nucleophilic attack by F– at co-ordinated CO. For M = Ru, the fluoroacyl complex is unstable at room temperature and decomposes via elimination of CO to [OC-6-13][RuF2(CO)2(PPh3)2] for which the ligand arrangement has been confirmed by X-ray crystallography. For M = Os, the analogous complex is obtained by heating the fluoroacyl species in solution for several hours. All the products have been characterised by IR, 19F and 31P NMR spectroscopies.

Molecular complexes of octafluoronaphthalene with acyclic and heterocyclic sulfur–nitrogen compounds

Abstract Mismatched molecular 1:1 complexes were prepared from C10F8 and sulfur diimides ArNSNAr 1 and ArNSN–SiMe3 2, 3 (1, 2: Ar=2,6–dimethylphenyl; 3: Ar=phenyl). In the case of 2, the complexation is accompanied by the unexpected cyclization of 2 into 7-methyl-2,1-benzisothiazole 4. The X-ray molecular structures of C10F8·1, C10F8·3 and C10F8 are presented; in C10F8·4 the 7-methyl-2,1-benzisothiazole 4 is highly disordered. The complexes provide very rare examples of markedly bent (C10F8·1), polyheteroatom (C10F8·3) and heterocyclic (C10F8·4) molecules involved in non-covalent arene-polyfluoroarene π-stacking interactions.

Three-coordinate sulphur(VI)-nitrogen species: an attempt to breathe some new life into an old topic

Abstract The review describes the syntheses, structures and reaction chemistry of three-coordinate nitrogen-containing sulphur(VI) compounds including the sulphur triimides [(RN) 3 S],

Arylthiazylamides: syntheses, structures, and bonding properties.

Air-sensitive, thermally unstable tris(dimethylamino)sulfonium (TAS) salts (3) of the title anions [ArNSN]- have been prepared from corresponding sulfurdiimides Ar-N=S=N-SiMe3 (2) by Si-N bond cleavage with [(Me2N)3S]-[Me3SiF2]- (TASF). They are characterized by low-temperature X-ray crystallography as Z isomers. Because of the very short terminal S-N distance (144.2 (3h)-147.9 (3i)pm) and the relatively long internal S-N distance (158.3 (3i)-160.3 (3c) pm) the [ArNSN]- ions should be regarded as thiazylamides 1b, rare species containing a S triple bond N triple bond. A bonding model is developed and the experimental results are compared with those of restricted Hartree-Fock (RHF), density functional theory (DFT), and Møller-Plesset second-order (MP2) calculations.

The first N-alkyl-N′-polyfluorohetaryl sulfur diimide

Abstract The first AlkNSNHetF sulfur diimide 6 (Alk=adamant-1-yl, HetF=2,3,5,6-tetrafluoropyrid-4-yl) was prepared by trapping of the corresponding alkylthiazylamide [AlkNSN]− 3 with pentafluoropyridine, followed by X-ray structural characterization. For 6, the Z,E configuration was found. From the reaction of 3 with octafluoronaphthalene, hexafluorinated naphthothiadiazole 7 was isolated along with the parent AlkNH2.

P3N3F5NPF2NPF2NPF52–: a Cyclophosphazene with a phosphazene side-chain dianion by F–-induced ring-opening of P3N3F6

[(Me2N)3S+]2[P3N3F5NPF2NPF2NPF5]2– is prepared from the reaction of (Me2N)3S+Me3SiF2–and P3N3F6 and its X-ray crystal structure determined.

Trithiatetrazocine Cations, [RCN4S3]+; Planar Sulfur−Nitrogen 10π Aromatics†

The reaction of bicyclic sulfur-nitrogen heterocyles RCN 5S 3 (R = F 3C, Ph, Me 2N, 2-FC 6H 4, 2,6-F 2C 6H 3) with [Hg(SO 2) 2][AsF 6] 2 in liquid SO 2 yielded the corresponding trithiatetrazocinium-hexafluoroarsenates [RCN 4S 3][AsF 6] as yellow solids and a red-brown insoluble byproduct with the approximate composition Hg 3N 2. Single crystal structure determinations of the salts and theoretical calculations on the trithiatetrazocine cations [RCN 4S 3] (+) revealed the cations to be planar eight-membered heterocycles. The [RCN 4S 3] (+) cations are the missing link in the series of known valence isoelectronic eight-membered 10pi azocines, that is, [S 4N 4] (2+) and RC(NSN) 2CR. In contrast to neutral trithiatetrazocines and dithiatetrazocines RC(NSN) 2CR carrying donor substituents, which have a folded butterfly structure with a transannular S-S bond, the positive charge on the [RCN 4S 3] (+) cations always stabilizes the planar structure independent of the nature of the substituent. Experimentally obtained structures and theoretical calculations (geometries, frequencies, charges, nucleus-independent chemical shifts (NICS)) are in agreement with the description of [RCN 4S 3] (+) as planar eight-membered 10pi Huckel aromatic. The single crystal structure determinations of some 3,5-R-1,2,4,6-thiatriazinyl hexafluoroarsenates (R = Ph, 2-FC 6H 4, 4-FC 6H 4), which were isolated from the above reaction as well, are also included.

F3CCN5S3, A BICYCLIC MULTIFUNCTIONAL SULFUR-NITROGEN LIGAND

The bicyclic sulfur-nitrogen heterocycle F3CCN5S3 (1) was investigated as a donor and acceptor toward H+, metal cations, and F−. Whereas the protonated species F3CCN5S3H+ AsF6 − (2) can be isolated, the product of the reaction with F− is unstable and decomposes among other products to TAS+ F3CCN5S3NC(NH2)CF3 − (3), which is isolated from this reaction in small amounts.

The preparation and crystal structure of the iridium thiazyldifluoride complex [Ir(CO)ClF(NSF2)(PPh3)2]

The thiazyldifluoride complex [Ir(CO)ClF(NSF2)(PPh3)2]2 was prepared by reaction of [Ir(CO)Cl(PPh3)2]1 and NSF3 and its X-ray crystal structure determined.