Abstract: The present invention is a time-based vehicle immobilizer useful for lenders. The Immobilizer has a base unit attached to the starter circuit of a vehicle and a wireless handheld unit. The base unit disables the vehicle starter circuit unless it receives a signal indicating a period of time from the handled unit. The handheld unit will only generate a signal if an activation code entered into a keypad on the unit corresponds to a reference code stored in the unit's memory. Each preloaded reference code represents a period of time and is deleted after matching with an activation code. When no amount of time remains on the base unit, the vehicle is immobilized at the next ignition attempt.

Abstract: Modified silacrown ethers are formed having the general formula: ##STR1## wherein R.sup.1 and R.sup.2 are organic radicals, hydrogen or groups which actively assist in the complexing of metal cations, n is an integer between 3 and 10 inclusive, and R.sup.3 is hydrogen or lower alkyl. These modified silacrown ethers are prepared by reacting a polyalkylene glycol with substituted silanes under conditions promoting cyclization over polymerization. The modified silacrown ethers are useful for forming cation complexes and promoting anionic reactions, particularly in phase transfer reactions either in solution or immobilized on siliceous supports.