Atom transfer radical polymerization.

Metal-catalyzed living radical polymerization.

Controlled/living radical polymerization: Features, developments, and perspectives

Current status and future perspectives in atom transfer radical polymerization (ATRP) are presented. Special emphasis is placed on mechanistic understanding of ATRP, recent synthetic and process development, and new controlled polymer architectures enabled by ATRP. New hybrid materials based on organic/inorganic systems and natural/synthetic polymers are presented. Some current and forthcoming applications are described.

Atom Transfer Radical Polymerization (ATRP): Current Status and Future Perspectives

Functional polymers by atom transfer radical polymerization

Synthesis, Characterization, and Molecular Structure of [{Sn(μ-NBut)2W(NBut)2}2]

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF [Pb5(η-CpS)4(OSO2CF3)6]

T h e prepara t ion and structural character isa t ion of [ S n f r i C s M e ^ S i M e i B u ^ K O S C K C F ; ! ) } : ] 1 is reported, including solidand solution-state mult inuclear N M R spect roscopic data and the molecu la r structure determination. The single crystal X-ray study revealed that 1 exists as an ionic species fo rmed by the aggregation of [Sn(r|-Cp )] cations and [Sn(r | -Cp )(0S02CF3)2] anions, which are held together by a Sn O S O S n bridging system. The N M R spectroscopic results suggest that the dimeric ion par structure exist only in the solid state, once in solution it dissociates into [Sn(r|-Cp)] and 0 S 0 2 C F 3 ions I N T R O D U C T I O N Compounds such as M(r | -\"Cp\") 2 {M = Sn, Ge or Pb} undergoes reaction with HBF4 and HOSO2CF3 producing half sandwich f ragments M( iv\"Cp\") + . In the case of the Sn(II) the half-sandwich complexes have been predominant ly described in the literature as ionogenic species either in solution or in the solid state [Sn(ri-\"Cp\")][X]\" {X = BF 4 } l ( c ) < f > or [ 5 η ( η ' ^ ρ \" ) ( Β ) ] + [ Χ ] ' {Β = py or b i p y and X = \"0S0 2CF 3} l , a ) ' , s , . Recently, we reported the synthesis and characterisation of the monomeric half sandwich compounds [Sn(r |-\"Cp\")Cl] and investigated its addition with SnCl2 3 . Also, some of us have reported the preparation of a Pb(II) der ivat ive, [Pb5(r | -Cp )4(0S02CF3)6] , which was obtained similar ly to l . 4 Here we report the s t ructural charac te r i sa t ion of a new half sandwich tr i f late der iva t ive , Sn( r | -Cp s ) (Q ,SCF: ! ) [Cp s = C5Me4SiMe2Bu'| and show how these ionogenic compounds exist in the solid state as the dimeric, ion-pair product. R E S U L T S A N D DISCUSSION Compound 1 was prepared by reacting one equivalent of H 0 S 0 2 C F 3 with [Sn{r)-C5Me4(SiMe2Bu')}2] in toluene. Af te r removing the solvent, X-ray quality crystals were obtained from a n-hexane solution. The molecular structure of 1 (Fig. I) have been determined and confirmed this compound to exist in the solid state as d imer ic \" t igh t \" ion pairs, composed of [Sn( r i -Cp s ) ] + ca t ions and surpr i s ingly , not \"0S0 2 CF 3 , but [Sn(r|-Cp )(OSO2CF3)2]\"ani0ns. The X-ray crystallography determination, Table 1, revealed that the Sn atoms interact unequally with the Ο atoms of both triflate groups. There are two distinct S n 0 interactions, S n ( l ) 0 ( 3 ) , S n ( l ) 0 ( 5 ) ; av. 2.991 A and [Sn(2)-0(1) , Sn(2) -0(4) ; av. 2.471 A, respectively. Table 2. Each triflate group interacts more strongly with Sn(2) than S n ( l ) which is weakly coordinated by a second oxygen atom of each triflate group. The S n ( l ) Ο interactions in 1 is s ignif icantly longer than those for Sn(2) and also longer than those measu red for [Sn (n -CsMe 5 ) (py ) ] [0S0 2 C F 3 ) 2 ] , 2 .842(5) and 2 . 8 6 1 ( 4 ) A . W i t h respec t to the Sncyclopentadienyl interactions, the cationic Sn( l ) -cent ro id dis tance is s ignif icant ly shorter than the Sncentroid distances found for [Sn{r | -C 5 Me 4 (S iMe 2 Bu , )} : ] 4 and [Sn(n-C 5 Me ? ) 2 f , 2 .379(2) and 2 .396 (av.) A r e s p e c t i v e l y and in g o o d a g r e e m e n t wi th o the r ionic Sn ( I I ) d e r i v a t i v e s such as [ S n ( r | C 5 Me 5 ) (py)] [OS0 2 CF 3 ) 2 ] , 2.237; [Sn( r | -C 5 Me)bipy) ] [0S0 2 CF 3 ) ; ] , 2.157; [Sn$l-C5Mes)][BF4] , 2 .157; [Sn(r |C s Me 4 {SiMe 2 (C<HMe 4 )}){BF 4 }] , 2.22; [Sn{n-C,H 4Bu'][BF 4 ] 2.182 and [Sn{r | -C<Me 4 (S iMe : Bu' )}{BF 4 }] , 2.143(8), 2.150(8) A . The solid state m S n N M R spectrum of 1 displayed two resonances, 5iso -2065, 2301. We assign the high f requency resonance to the anionic Sn(2) and the low frequency resonance to the cationic Sn ( l ) . The later was assigned on the basis of the similarity of the isotropic shifts (5 i s0) of S n ( l ) with those of [Sn(r | CsMes)][BF4] 5iso -2280 and [{Sn(r | -Cp )} {BF4}] 5, s o-2289. The solution state \" 9 Sn N M R spectra, however , displayed a single resonance at δ 2 1 7 0 . The N M R results sugest that the structure of 1, as [Sn(r)-Cp)f and [Sn(Cp s ) (0S0 2 CF 3 ) 2 ] ions, exist only in the solid state. Once in solution it dissociates into [Sn(r | -Cp ' ) ] and '

THE SYNTHESIS, CHARACTERISATION AND MOLECULAR STRUCTURE OF [{Sn(η-C5Me4SiMe2But)(OSO2CF3)}2]

Cationic hydride complexes of bis(cyclopentadienyl)tungsten(IV) have been prepared and studied. The complex [W(η-C5H5)2H(thf)][SO3CF3] reacts with CS2 in d6-acetone to form the chelated O-alkyl dithiocarbonate tungsten hydride insertion product [W(η-C5H5)2(η2-S2COCH(CD3)2-S,S′)][SO3CF3] as demonstrated by single crystal X-ray diffraction and NMR spectroscopy. The styrene complex [W(η-C5H5)2H(η2-CH2CHC6H5)][PF6] has been prepared as a mixture of exo and endo isomers. This isomeric mixture reacts thermally with NCMe to give [W(η-C5H5)2(CH2CH2C6H5)(NCMe)][PF6] and photochemically with NCMe to give [W(η-C5H5)2H(NCMe)][PF6]. The molecular structures of the exo isomer and of the benzonitrile complex [W(η-C5H5)2H(NCPh)][SO3CF3] are reported.

Synthesis and characterisation of cationic bis(cyclopentadienyl)tungsten(IV) complexes

S u m m a r y : The compound, [Ca{Sn^-OSiMe 2 Bu' ) 3 } 2 ] 1, was prepared by the condensation reaction of Ca(OSiMe 2Bu') 2 with Sn(OSiMe2Bu')2 in dme. The structural characterisation revealed that 1 crystallises in the monoclinic system {Space group P2,/n (non-standard NP 14)}. Each of the two S n ^ O S i M e 2 B u ' ) 3 anion binds the Ca(II) cation in an η 6 fashion [av. Ca Ο 2.408 A ]. Mult inuclear [ l 3 C, \" S i and \" 9 S n ] solid-state N M R spectroscopic studies are also reported. Compound 1 showed satisfactory elemental analysis.

David J. Duncalf

Papers

Synthesis, Characterization, and Molecular Structure of [{Sn(μ-NBut)2W(NBut)2}2]

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF [Pb5(η-CpS)4(OSO2CF3)6]

THE SYNTHESIS, CHARACTERISATION AND MOLECULAR STRUCTURE OF [{Sn(η-C5Me4SiMe2But)(OSO2CF3)}2]

Synthesis and characterisation of cationic bis(cyclopentadienyl)tungsten(IV) complexes

SYNTHESIS, CHARACTERISATION AND MOLECULAR STRUCTURE OF A CALCIUM STANNYL DERIVATIVE: Ca{Sn(μ-OSiMe2But)3}2