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The monomeric trinitrosyl complex, W(NO)^sub 3^Cl^sub 3^, can be prepared by the treatment of WCl^sub 6^ in CH^sub 2^Cl^sub 2^ with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmw2^sub 1^ as a three-component twin (a = 10.4280(4) [Angstrom], b = 6.3289(2) [Angstrom], c = 5.6854(2) [Angstrom], Z = 2, R^sub 1^ = 0.065, wR^sub 2^ = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W-N linkages are 1.88(2) and 1.92(1) [Angstrom] long, while the two corresponding N-O bond lengths are 1.13(2) and 1.16(2) [Angstrom]. DFT calculations on fac-W(NO)^sub 3^Cl^sub 3^ at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO)^sub 3^Cl^sub 3^ in CH^sub 2^Cl^sub 2^ lose ClNO under ambient conditions and deposit the well-known [W(NO)^sub 2^Cl^sub 2^]^sub n^ polymer, and this conversion is fully reversible. [PUBLICATION ABSTRACT] Key words: nitrosyl, tungsten, structure, bonding.

The monomeric trinitrosyl complex, W(NO) 3 Cl 3 , can be prepared by the treatment of WCl 6 in CH 2 Cl 2 with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmn2 1 as a three-component twin (a = 10.4280(4) Å, b = 6.3289(2) Å, c = 5.6854(2) Å, Z = 2, R 1 = 0.065, wR 2 = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W—N linkages are 1.88(2) and 1.92(1) Å long, while the two corresponding N—O bond lengths are 1.13(2) and 1.16(2) Å. DFT calculations on fac-W(NO) 3 Cl 3 at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO) 3 Cl 3 in CH 2 Cl 2 lose ClNO under ambient conditions and deposit the well-known [W(NO) 2 Cl 2 ] n polymer, and this conversion is fully reversible.Key words: nitrosyl, tungsten, structure, bonding.

Reaction of CpMo(NO)(CH 2 Ph)Cl with Me 2 Mg, Ph 2 Mg, or PhCCLi reagents in THF affords the corresponding alkyl, aryl, or alkynyl CpMo(NO)(CH 2 Ph)R (R = hydrocarbyl) complexes as orange powders in good yields. Unlike related 16-electron CpMo(NO)R 2 complexes, these 18-electron species exhibit good thermal stability due to their η 2 -benzyl-Mo interactions. Treatment of CpMo(NO)(CH 2 Ph)Cl with Na(DME)Cp provides dark green Cp 2 Mo(NO)(CH 2 Ph), whose solid-state molecular structure has been established by a single-crystal X-ray crystallographic analysis. The two Cp rings display different binding modes to the Mo atom, while the benzyl ligand is coordinated to the metal centre in an η 1 fashion. The triflate complex, CpMo(NO)(CH 2 Ph)(OTf), is obtained by addition of AgOTf to the benzyl chloride precursor. The covalent Mo—OTf bond in this compound can be disrupted by the addition of Lewis bases (L) such as PPh 3 or pyridine, leading to the corresponding [CpMo(NO)(CH 2 Ph)(L)][OTf] salts. Attempts to generate neutral benzylidene complexes by deprotonation of [CpMo(NO)(CH 2 Ph)(PPh 3 )][OTf] have not yet been successful.Key words: nitrosyl, molybdenum, benzyl, hydrocarbyl, triflate.

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