No abstract

13 C-{ 1 H}: c 79.1 [s, CH 2 (bridging)], 76.8 [s, CH 2 (terminal)], 16.9 [s, CH 3 (bridging)], 16.8 [s, CH 3 (terminal)] Mass (FAB): m/z 603 (M ϩ ) 5 [Mo{(η-C 5 H 4 )C(C 5 H 10 )-(η-C 5 H 4 )}Cl 2 ]

Nuclear magnetic resonance studies on [W(q-C,Me,Et) (CH,D),] [PF,] show a strong temperature dependence of the isotope shift [6(CH,) -6(CH2D)] indicating the presence of a monoagostic methyl group. The magnitude and sign of the geminal coupling constant 2J(H-D) [and 2J(H-H)] and the isotope shift, together with the temperature dependence of this shift, have been recorded for [Ti(CH,D)CI,], [Ti(CH,D)Cl,(dmpe)] (dmpe = Me,PCH,CH,PMe,), [Ta(CH,D),CI,.,] (n = 1-3), [M(q-C,H,),(CH,D),] (M = Ti, Zr or Hf), [M(q-C,H,),(CH,D)(thf)][BPh,] ( M = Ti or Zr, thf = tetrahydrofu ra n) I [Ti (77 -C5H5)2( c H, D 1 FI I [Zr(q -C5H5)2 ( c H, D 1 ( M eCN 121 B Ph41 r [Ti (77 -C,Hd ( c H, D ) 31 r [ M (q -C,Me,Et)(CH,D),] ( M = Ti, Zr or H f ) and [Y(q-C,Me,),(CH,D)(thf)].The isotope shifts for all these complexes are essentially temperature independent. A convenient synthesis of Li (CH,D) is described.

Monoadduct derivatives of the fullerene c60, namely [Fe(C0)4(q2-C60)], [ M O ( T ~C ~H ~R ) ~( ~~-C ~~) ] (R = H, Bun), [Ta(q2-C5H5)2(~2-C60)H] and [Rh(Ph3P)2(Co)(q2-C6~)H], are described.

The new compounds [W{(η-C 5 H 4 )X(η-C 5 H 4 )}Cl 2 ] 1, [W{(η-C 5 H 4 )X(η-C 5 H 4 )}Me 2 ] 2, [W{(η-C , where X = SiMe 2 , SiEt 2 or CMe 2 CMe 2 , and Y = BF 4 or Cl, have been prepared. The crystal structures of [W{(η-C 5 H 4 )X(η-C 5 H 4 )}Me 2 ] (X = SiMe 2 or CMe 2 CMe 2 ) have been determined.Recently we have described ansa-metallocenes of tungsten and molybdenum and shown that their properties are significantly different from non-ansa analogues. 1,2 In particular we noted that the complex [W{(η-C 5 H 4 )CMe 2 (η-C 5 H 4 )}H 3 ] ϩ PF 6 Ϫ displays exceptional highly temperature variable 1 H NMR spectroscopic data with 2 J(HH) of ca. 16 000 Hz at Ϫ70 ЊC attributed to quantum mechanical exchange coupling. By comparison, [W(η-C 5 H 5 ) 2 H 3 ] ϩ BF 4 Ϫ shows very different temperature independent behaviour. 3 We have prepared a number of related ansa-tungstenocene complexes to investigate the effect that changes in the bridging ring substituents have upon their properties.Compound and analysis a 1a [W{(η-C 5 H 4 )SiMe 2 (η-C 5 H 4 )}Cl 2 ] Green C, 28.7 (28.7); H, 3.7 (3.3) Spectroscopic data b 1 H: c 6.12 (4 H, m, C 5 H 4 ), 5.81 (4 H, m, C 5 H 4 ), 0.09 (6 H, s, Me 2 Si) 13 C-{ 1 H}: c 125.9 (s, C 5 H 4 ), 78.7 (s, C 5 H 4 ), 66.0 (s, C 5 H 4 , C ipso ), Ϫ5.9 (s, SiMe 2 ) Mass (FAB): m/z 442 (M ϩ ), 405 (M ϩ Ϫ Cl) 1b [W{(η-C 5 H 4 )SiEt 2 (η-C 5 H 4 )}Cl 2 ] Green 1