Non-polymeric molybdenum(ii) complexes of dicarboxylic acids: synthesis, structure and catalytic properties

[Mo 2 (MeCN) 8 ][BF 4 ] 4 reacts with α,ω-dicarboxylic acids [HO 2 C(CH 2 ) n CO 2 H, n = 0–8] to form salts with empirical formula [Mo 2 {O 2 C(CH 2 ) n C O 2 }(MeCN) x ][BF 4 ] 2 ; the X-ray crystal structure of the butanedioic salt [Mo 4 {η 2 -µ-O 2 C- (CH 2 ) 2 CO 2 -µ-η 2 } 2 (MeCN) 12 ][BF 4 ] 4 ·3MeCN is reported together with the use of the complexes as catalysts for the polymerization of norbornene.