The titanium(II) derivatives Ti(η6-arene)[(µ-X)2(AlX2)]2, (X = Br or I) in the parent aromatic hydrocarbon react with CO at atmospheric pressure to give thermally unstable complexes of proposed structure Ti[(η6-arene)(CO)2(µ-X)2-(AlX2)]AlX4 and with C2Ph2 to give tetra-substituted cyclobutadiene derivatives Ti(η4-C4Ph4)[(µ-X)2(AlX2)]2(X = Br)